42 resultados para Keyed One-Way Functions
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从2006 年10 月24 日至2007 年4 月9 日,采用固定样线法和瞬时扫描法, 对在大山包国家级自然保护区(N27°18′38″~27°29′15″,E103°14′55″~103°23′49″) 内越冬的黑颈鹤种群进行了越冬行为、日间活动节律和越冬栖息地利用的详细调 查,同时对黑颈鹤的春季迁徙行为和冬季黑颈鹤的死亡现象进行了观察和分析。 这些研究有助于我们了解黑颈鹤是采取何种行为模式和栖息地利用模式来适应高 海拔、低温度的环境,同时对如何有效地保护越冬黑颈鹤和合理规划保护区功能 区域有重要的指导作用。 将黑颈鹤的越冬行为分为:取食(Feeding)、搜寻(Searching)、警戒(Vigilance)、 争斗(Fight)、行走(Walk)、飞行(Flight)、休整(Maintenance)和其它(Others) 八种,越冬期间最主要的行为是取食(53.05±4.93)%,其它行为依次为:搜寻 (10.38±1.34)%、警戒(18.75±2.65)%、休整(10.32±4.93)%、行走(4.90±1.59) %、飞行(1.70±0.38)%、争斗(0.36±0.25)%、其它(0.55±0.41)%。单因素 方差分析(One-Way ANOVA)分析表明越冬期间黑颈鹤日间各时间段(1h)和各 月份间行为差异极显著(P<0.05),并呈现出规律的变化。黑颈鹤的取食、警戒、 搜寻行为具明显的早(10:00-11:00)、晚(17:00-18:00)两个活动高峰,中午 13:00~14:00 最低;而休整行为正好相反,呈现出中午高峰、上午和下午低谷的趋 势;另外几种行为节律性表现不明显。黑颈鹤越冬期主要行为的节律变化是受环 境温度变化影响的,温度高时黑颈鹤增加了修整时间减少了取食时间,而温度低 时则减少了修整时间增加了取食时间以维持能量需求,湿度是通过温度对黑颈鹤 产生影响的。每天黑颈鹤都随着太阳的升起开始觉醒,于07:18±0:15 飞离夜栖地, 大雾的天气影响了黑颈鹤的外出觅食,与之相适应的是黑颈鹤相应的推迟了出飞 时间。黑颈鹤所采取的所有行为都表现出了对大山包特殊环境的适应。 在大山包黑颈鹤所利用的栖息共有耕地(farmland)、草地(grassland)、沼泽 (marsh)和浅水水域(water area)四类。选择指数分析表明黑颈鹤对水域有极大 的偏好,其次为沼泽湿地,再次为耕地,而对草地表现为负选择,并且在越冬期 间的各月份之间,对不同栖息利用比率保持一致。这提示我们在进行保护区规划 的时候应该适当增加前三种栖息地的面积以满足黑颈鹤的越冬需求。主成份因子 分析表明黑颈鹤倾向于选择距夜栖地和水源较近、人流较少、干扰较小、无坡或缓坡的低海拔栖息地。处于不同越冬地的越冬黑颈鹤根据当地的实际情况采取不 同的栖息地利用,说明黑颈鹤具有较强的环境适应能力。 调查期间记录到了三只带有彩环的黑颈鹤个体,其中有两只佩戴有卫星发射 器,发射器编号分别为64309 和64311。大山包黑颈鹤种群数量变动的春季和秋季 高峰是由于处于不同越冬地的黑颈鹤迁徙造成的,同时也说明了大山包是在滇东 北和黔西北越冬的黑颈鹤的集散地。黑颈鹤的春季迁徙一般集中在3 月下旬至4 月上旬,在晴朗、微风的上午10:00-11:00 迁徙的黑颈鹤数量最多,说明了天气条 件对黑颈鹤迁徙的重要性。 大山包保护区内的高压输电电线和通信电缆对越冬黑颈鹤构成了极大的威 胁。观察期间共有7 只黑颈鹤因撞上输电电线而死亡,除去一只没有外伤的成体 之外,成幼比例为1:1,大都发生在天气较为恶劣的12 月-2 月之间。发生撞死黑 颈鹤的时候保护区内都有不同程度的大雾笼罩,由于大雾的影响造成可视条件下 降,加之黑颈鹤飞行的机动性差(翼载量大、展弦比不大),造成了黑颈鹤的伤亡.
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2007 年9 月5 日至11 月5 日和2008 年9 月3 日至11 月7 日期间,主要利用灯光诱捕,对云南省新平县哀牢山金山丫口(23°57′N, 101°30′E)夜间迁徙鸟类多样性进行调查。同时记录网捕鸟类的时序和几种主要鸟类的迁徙时序。分析各种因子(地理、温度、湿度、雾天、风向、风力以及月相周期)对夜间网捕鸟类数量和种类的影响。 2 年期间共网捕鸟类7943 只,129 种,分别属于14 目23 科。雀形目鸟类占总网捕数量的58.9%。网捕数量超过1%的科共10 个科。网捕数量占总网捕数量1%以上的共14 种。其中红尾伯劳Lanius cristatus、小杜鹃Cuculus poliocephalus、红喉歌鸲Luscinia calliope 三者的数量超过网捕鸟类总数的5%。所有网捕鸟类中,东洋型鸟类占最多共54 种,占41.85%。 2 年期间网捕鸟类多样性指数H′为2.60989,均匀度指数J 为0.29063,优势度指数C 为 0.22503,G-F 指数为0.71366。2007 年的优势指数C 和G-F 指数较2008 年高,但2008 年的 Shannon-Wiener 指数和Pielou 指数较2007 年高。红尾伯劳是造成两年多样性测度指数差异的主要原因。云南省不同“打雀山”夜间捕获鸟类的种类和数量存在差异。地理和气候可能是造成这些差异的主要因素。 2 年工作期间将观察时间平均分为早期(9 月3 日至9 月24 日)、中期(9 月25 日至10 月16 日)、晚期(10 月17 日至11 月8 日)三个时期。早期网捕鸟类数量最多5263 只,多样性指数最低,优势度指数最高;中期记录的种类最多86 种,多样性指数和均匀度指数中期最高。造成这种差异的主要原因是早期红尾伯劳的数量尤其突出。单独分析2007 年和2008 年各时期,除了2007 年晚期种类最多67 种以外,其余变化都与2 年总体一致。每个时期都有部分鸟类数量达到高峰,而也有部分鸟类数量处在低谷期。飞经哀牢山金山丫口的秋季夜间迁徙鸟类开始迁徙的时间大致在8 月中旬,结束在11 月下旬。每种鸟类的迁徙持续时间不一致,其中迁徙持续时间超过30 天的鸟有36 种。同种鸟类不同年份迁徙时间不一致。夜间每个时段捕获数量和种类有差异,在夜间20:00-22:00 和凌晨04:00-06:00 捕获数量和种类较多。24:00-02:00 网捕鸟类数量和种类最少。调查结果显示不是所有鸟类都是整夜迁徙,夜间开始迁徙较早的鸟类清晨也停止迁徙较早,夜间开始迁徙较晚的鸟类清晨停止迁徙较晚。除红喉歌鸲以外的4 种鸟,它们的迁徙时间是从9 月前至11 月后。红尾伯劳、小杜鹃以及大杜鹃的迁徙高峰期是9 月上旬至9 月中旬。厚嘴苇莺Acrocephalus aedon 的迁徙高峰期为 9 月中旬至10 月下旬。红喉歌鸲的迁徙时间是9 月下旬至11 月上旬后,迁徙高峰期为整个 10 月。5 个优势种都是整夜迁徙,不过每种鸟的迁徙高峰时段和低谷时段不一致。红尾伯劳、小杜鹃、大杜鹃在20:00-22:00 捕获数量最多;红喉歌鸲、厚嘴苇莺在凌晨04:00-06:00 捕获数量最多。红尾伯劳、红喉歌鸲、大杜鹃在24:00-02:00 捕获数量最少;厚嘴苇莺在22:00-24:00 捕获数量最少;小杜鹃在凌晨02:00-04:00 捕获数量最少。对5 个优势种在各迁徙时期的体重进行分析,采用双样本T 检验(Independent-Samples T Test)表明:红喉歌鸲和小杜鹃早中晚期的体重差异极为显著(P<0.01)。运用单因素方差分析(One-Way ANONA)表明:小杜鹃早中晚期的体重变化极其显著(P<0.01)。进一步采用双样本T 检验(Independent-Samples T Test):小杜鹃晚期体重与早期和中期体重差异都极其著(P<0.01),早期与中期的体量没有显著差异(P>0.01)。其余3 个优势种各时期体量差异不显著(P>0.01)。影响夜间网捕鸟类种类和数量的因素较多。地理特点是影响夜间网捕鸟类种类的主要因素。气候条件是影响夜间网捕鸟类种类和数量的重要因素。风向和风力对夜间网捕数量和种类都有极其显著的影响(P<0.01),其中风向对其影响比风力大,西南风时夜间网捕鸟类数量和种类较多。雾天对夜间网捕数量和种类影响极其显著(P<0.01),大雾天气夜间网捕鸟类数量和种类较多。月相周期对夜间网捕数量及其种类的影响极其显著 (P<0.01),新月和残月期间夜间网捕鸟类数量和种类较多。温湿度对夜间网捕鸟类数量和种类影响不显著(P>0.05)。除此之外,光也是捕获夜间鸟类的必要条件。
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已有的研究表明,眶额叶在解剖上与现在已知的药物滥用相关的脑区是紧密联系在一起的。例如,眶额叶在药物滥用和强迫性重复行为中起作用,且随着脑成像技术的应用,越来越多的证据表明眶额叶参与了药物滥用。但是我们并不了解在阿片给药和戒断期间眶额叶脑区活动是如何变化的。因此,我们在实验中采用了Mn2+增强的核磁共振成像(Manganese-enhanced magnetic resonance imaging,MEMRI,4.7T)技术和脑电(EEG)记录的方法,以研究大鼠眶额叶在给与阿片类药物(盐酸吗啡)以及戒断过程中的动态变化。 MEMRI是一种近年才发展起来的新型技术。研究表明,Mn2+是Ca2+的类似物,可以通过Ca2+通道进入兴奋性的神经元里面并结合到胞内的蛋白质和核酸上的Ca2+和Mg2+结合位点上 (MILDVAN and COHN, 1963; EISINGER et al., 1965)。另外,Mn2+的顺磁性也为它成为核磁共振成像的造影剂提供了前提条件。可是成功应用MEMRI的前提就是要在适当的时间把合适剂量的Mn2+传递到靶点上。因此,Mn2+在注射到靶点后,是否能够在有效的时间内反映大脑活动的变化就成为一个非常重要并且在技术上较为棘手的问题。在给实验大鼠脑区微量注射Mn2+(80mMol/L,200nl)的同时,通过微量注射兴奋性神经递质谷氨酸(Glu 0.5mM/L)或抑制性递质γ-aminobutyric acid(GABA 0.5M/L)以改变靶点神经元兴奋性的方法,检测Mn2+能否反映脑区的活动变化。另外,我们随机选取实验动物,分别在注射Mn2+ 3小时、5小时和8小时后对三组大鼠(n=5)进行10%福尔马林灌流,并且通过观察大鼠眶额叶脑区Mn2+强度的变化来研究最佳的灌流时间。我们的实验结果表明,Mn2++Glu组的右侧脑区/左侧脑区的Mn2+亮度比Mn2+空白对照组增加了20%(p=0.016, student t-test, *p <0.05),也远大于Mn2++GABA组(p=0.047, *p<0.05)。结果表明,当神经元被兴奋的时候,较多的Mn2+可以通过Ca2+通道进入兴奋的神经元内,使得Mn2+的成像亮度增加。由于Mn2+成像亮度的增加可以反映神经元的兴奋活动,因此可以显示出靶点区的脑活动。另外,在研究灌流时间对Mn2+亮度影响的实验中发现,注射Mn2+ 5小时后灌流得到的信噪比分别比注射Mn2+3小时(p=0.055)和8小时(p=0.004,*p<0.05)高出24%和32%。总之,我们采用微量注射Mn2+(80mM/L,200nl)后5小时用10%福尔马林心脏灌流的方法获得了较好的结果。另外在试验中我们首先观测了大鼠吗啡戒断后的行为学指标和检测大鼠戒断后条件化位置偏好的程度。实验结果表明大鼠可以建立非常明显的条件化位置偏好,但在湿狗抖等行为学指标上无明显症状。这说明大鼠对于吗啡(10mg/kg, 一天两次,持续12天)形成了明显的心理依赖而无明显的生理依赖。此外,MEMRI的结果表明,在吗啡给药的第1天和第6天,大鼠眶额叶的Mn2+强度与空白对照组相比有显著的降低( one-way ANOVA, Post Hoc Dunnett’s C Tests), F (6,28)=7.242, P<0.001);而在戒断第3天又恢复到正常水平,在戒断第5天和第7天Mn2+强度跟空白对照组相比没有显著性差别(one-way ANOVA, *p<0.05)。脑电(EEG)的结果表明,急性吗啡诱导的gamma波段的EEG显著降低(Two-way ANOVA, F(1,10)=13.626,p=0.006)。然而在戒断第1天gamma波段的EEG与空白对照组相比是增加的。在戒断第3天和戒断第5天,gamma波段的EEG与空白对照组相比也有显著性增强。以上研究结果表明:大鼠眶额叶脑区的动态变化与整个吗啡给药和戒断过程是密切相关的;此外,MEMRI在探讨药物滥用以及成瘾等机制上有很大的应用前景。
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While Histograms of Oriented Gradients (HOG) plus Support Vector Machine (SVM) (HOG+SVM) is the most successful human detection algorithm, it is time-consuming. This paper proposes two ways to deal with this problem. One way is to reuse the features in blocks to construct the HOG features for intersecting detection windows. Another way is to utilize sub-cell based interpolation to efficiently compute the HOG features for each block. The combination of the two ways results in significant increase in detecting humans-more than five times better. To evaluate the proposed method, we have established a top-view human database. Experimental results on the top-view database and the well-known INRIA data set have demonstrated the effectiveness and efficiency of the proposed method. (C) 2010 Elsevier B.V. All rights reserved.
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Two- and three-dimensional Au nanoparticle/[tetrakis(N-methylpyridyl)porphyrinato]cobalt (CoTMPyP) nanostructured materials were prepared by "bottom-up" self-assembly. The electrocatalytic and plasmonic properties of the Au nanoparticle/CoTMPyP self-assembled nanostructured materials (abbreviated as Au/CoTMPyP SANMs) are tunable by controlled self-assembly of the An nanoparticles and CoTMPyP on indium tin oxide (ITO) electrode. The electrocatalytic activity of the Au/CoTMPyP SANMs can be tuned in two ways. One way is that citrate-stabilized An nanoparticles are positioned first on ITO surface with tunable number density, and then positively charged CoTMPyP ions are planted selectively on these gold sites. The other way is that An nanoparticles and CoTMPyP are deposited by virtue of layer-by-layer assembly, which can also tune the amount of the as-deposited electrocatalysts. FE-SEM studies showed that three-dimensional SANMs grow in the lateral expansion mode, and thermal annealing resulted in both surface diffusion of nanoparticles and atomic rearrangement to generate larger gold nanostructures with predominant (I 11) facets.
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The chloroplasts, mitochondria, and protoplasm devoid of mature chloroplasts (PMC) of Bryopsis hypnoides Lamouroux were isolated by low-speed and sucrose density centrifugation. The PMC aggregated in artificial seawater, and then protoplasts without mature chloroplasts (PtMCs) were formed. Transmission electron microscopy and cytochemical studies indicated that there were mitochondria, nuclei, vesicles, and other small cell organelles in the PtMCs. Scanning electron microscopy showed that there were holes on the surface of 1-h PtMCs and then fewer holes on the surface of 24-h PtMCs, suggesting that a healing process occurred. The plasma membrane was formed over the surface of the PtMCs. However, the cell wall was not regenerated, and the newly formed PtMCs were ruptured and died in 3 days. Light intensity during alga maintenance before use influenced significantly (one-way ANOVA, P < 0.0001) on the number of PtMCs formed; the highest number of PtMCs was formed at 20A mu mol/(m(2) s). When isolated chloroplasts were transferred into seawater, there were only two or three chloroplasts aggregated together. However, isolated mitochondria and the mixed six layers of cell organelles (separated by sucrose density centrifugation) could not aggregate in the artificial seawater. This indicates that the conjunction of cell organelles is important for their aggregation.
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We applied a primitive equation ocean model to simulate submesoscale activities and processes over the shelf of the northern South China Sea (NSCS) with a one-way nesting technology for downscaling. The temperature and density fields showed that submesoscale activities were ubiquitous in the NSCS shelf. The vertical velocity was considerably enhanced in submesoscale processes and could reach an average of 58 m per day in the subsurface. At this point, the mixed layer depth also was deepened along the front, and the surface kinetic energy also increased with the intense vertical movement induced by submesoscale activity. Thus, submesoscale stirring/mixing is important for tracers, such as temperature, salinity, nutrients, dissolved organic, and inorganic carbon. This result may have implication for climate and biogeochemical investigations.
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本文利用不同的分子标记方法,分别对牙鲆及大黄鱼不同养殖群体的生长、抗病等经济性状的候选基因进行了序列多态性研究,检测到了几个SNP位点和微卫星的多态性位点,并分析了它们与经济性状之间的相关性;同时,利用微卫星的多态性位点对牙鲆2个养殖群体的遗传变异进行了分析,这些均为海水鱼类遗传育种及标记辅助选育工作提供了基础数据。 在牙鲆胶南养殖群体中,以100个个体为实验材料,根据其生长激素(GH)基因的6个外显子序列设计引物,通过SSCP分析技术显示该群体GH基因的第4外显子存在多态性,检测到2种基因型,AA型和AB型。DNA测序结果表明,AB型在第1763位发生碱基突变,c→t,与AA型同源性达到99%。连锁分析结果表明:这2种基因型的个体在体重和头长上表现出显著的差异,AB型个体的体重和头长都明显大于AA型个体(P<0.05),由此推测等位基因B是一个对牙鲆体重和头长都有利的等位基因;这2种基因型个体之间在其体型性状上也存在显著差异(P<0.05);同时,该多态位点的Hardy-Weinberg平衡性检验结果表明,该群体处于Hardy-Weinberg平衡状态。在牙鲆GH基因第1外显子区域还发现了一个微卫星位点,对该位点进行多态性分析,检测到5种基因型、3种等位基因,one-way ANOVA统计结果显示,基因型AC个体的体重、头长和体高明显大于其它基因型个体(P<0.05),C是一个对体重、头长和体高有利的等位基因。 对2个大黄鱼养殖群体的GH基因进行SSCP分析后发现,浙江群体大黄鱼GH基因在第196位存在1个SNP(g→a)位点,检测到2种基因型,AA和AB。t检验结果表明,AA型个体的体高比AB型个体的高(P≤0.05),但AB型个体在体长/体高上占优势(P≤0.05),提示该突变位点可以作为大黄鱼体型性状的候选标记。福建群体大黄鱼GH基因在第692位有1个SNP位点(t→c),共检测到2种基因型,CC型和CD型,其中,CD基因型个体的体重和全长显著大于CC基因型个体(P≤0.01),提示该位点可以作为大黄鱼体重和头长性状的候选标记。 在牙鲆胶南和日照2个养殖群体中,采用牙鲆GHR基因5’端Promoter区的一个微卫星标记,进行了群体遗传变异的研究,并探索了该基因多态性位点与牙鲆生长性状之间的相关性。结果表明,2个群体在该位点检测到的等位基因数为12和9个,有效等位基因数为6.26和5.04个。两个群体该位点的Hardy-Weinberg遗传偏离指数均为正值,并没有显示出杂合子缺失,但各基因型分布频率都在一定程度上偏离Hardy-Weinberg平衡(P<0.01)。连锁分析发现,在胶南群体中,IM基因型对应的个体在全重、全长、体长、头长、体高和眼径形态学数据中均是最大的,但仅在体重上极其显著的大于全部其它基因型个体;在日照群体中,BC基因型对应的个体在全重、全长、体高、尾柄高、尾柄长和眼径数据中均是最大的;而CJ基因型对应的个体在体长和头长这两组数据中是最大的。由此认为,该位点IM基因型可以作为牙鲆体重性状的潜在标记。 在进行牙鲆抗病性状标记的筛选时,利用迟缓爱德华氏菌(Edwardsiella tarda)LSE40对牙鲆鱼进行攻毒感染实验,得到死亡群体和未死亡群体。选择Toll样受体基因中的TLR2、TLR3和TLR9基因作为候选基因,分别对这3个基因中的部分序列共设计7对引物进行扩增,同时对扩增产物进行RFLP多态性分析,目前只在TLR3基因内检测到一个EcoRI的酶切多态性位点,测序后发现,这是由于在TLR3基因第3806位的EcoRI酶切位点在某些个体中缺失所致。酶切产物共呈现出3种基因型,分别定义为AA,AB和BB。χ2检验证明该多态性位点与牙鲆抗迟缓爱德华氏菌LSE40的能力有一定关系。利用多因素非条件Logistic回归分析对死亡组和存活组牙鲆的各种形态学数据以及不同基因型之间进行了分析,发现体长、头长和体高均具有显著的相关性(P<0.05),而这几个因素与体重的相关性不显著(P>0.05)。多因素非条件Logistic分析后发现:AA基因型对死亡率具有显著的影响(P<0.05),是主要的危险因素,而AB基因型的作用不显著(P>0.05);头长是主要的保护因素(P<0.05),体重对死亡率的影响很小。χ2检验证明,等位基因A是对死亡的主要危险等位基因,B是对存活有利的主要等位基因。推测该位点可以作为牙鲆抗迟缓爱德华氏菌的潜在标记。
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Rates of respiration and excretion of the Pacific oyster, Crassostrea gigas, were measured seasonally from June 2002 to July 2003 under ambient conditions of food, water temperature, pH, and salinity in Sanggou Bay, an important mariculture coast in north China. The aim of this study is to obtain fundamental data for further establishing an energy budget model and assessing the carrying capacity for cultivation of C. gigas in north China. Oysters were collected monthly or bimonthly from the integrated culture areas of bivalve and kelp in the bay. Oxygen consumption and ammonium and phosphorus excretion rates were measured, and ratios of O/N and NIP were calculated. One-way ANOVA was applied to determine differences among these parameters that act as a function of seasonal variation. All the physiological parameters yielded highly significant variations with season (P<0.01) The rate of respiration varied seasonally, with the highest oxygen consumption rate in July and the lowest rate in January, ranging from 0.07 to 2.13 mg O-2 h(-1) g(-1) dry tissue weight (DW). Maximum and minimum ammonium excretion rates were recorded in August and January, respectively, ranging from 0.51 to 5.40 mu mol NH4-N h(-1) g(-1) DW. Rates of phosphorus excretion varied from 0.11 (in January) to 0.64 (in July) mu mol PO4-P h(-1) g(-1) DW. The O/N and N/P ratios changed from 9.2 (in January) to 59.8 (in July) and from 4.6 (in January) to 10.9 (in August), respectively. For each season, the allometric relationship between the physiological response (e.g., rate of oxygen consumption, ammonium and phosphorus excretion) and DW of the animal was estimated using the formula: Y=a x DWb. (C) 2005 Elsevier B.V. All rights reserved.
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本文研究了CIMS环境下的生产计划问题.考虑了两种市场需求驱动生产方式,一种是在计划周期内各阶段市场需求由预先订货决定,另一种是市场需求不是由预先订货决定,而是一个随机变量.但可根据统计,确认它服从某种分布规律,对于这两种生产方式,本文可给出最优的生产计划。
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Attaining sufficient accuracy and efficiency of generalized screen propagator and improving the quality of input gathers are often problems of wave equation presack depth migration, in this paper,a high order formula of generalized screen propagator for one-way wave equation is proposed by using the asymptotic expansion of single-square-root operator. Based on the formula,a new generalized screen propagator is developed ,which is composed of split-step Fourier propagator and high order correction terms,the new generalized screen propagator not only improving calculation precision without sharply increasing the quantity of computation,facilitates the suitability of generalized screen propagator to the media with strong lateral velocity variation. As wave-equation prestack depth migration is sensitive to the quality of input gathers, which greatly affect the output,and the available seismic data processing system has inability to obtain traveltimes corresponding to the multiple arrivals, to estimate of great residual statics, to merge seismic datum from different projects and to design inverse Q filter, we establish difference equations with an embodiment of Huygens’s principle for obtaining traveltimes corresponding to the multiple arrivals,bring forward a time variable matching filter for seismic datum merging by using the fast algorithm called Mallat tree for wavelet transformations, put forward a method for estimation of residual statics by applying the optimum model parameters estimated by iterative inversion with three organized algorithm,i.e,the CMP intertrace cross-correlation algorithm,the Laplacian image edge extraction algorithm,and the DFP algorithm, and present phase-shift inverse Q filter based on Futterman’s amplitude and phase-velocity dispersion formula and wave field extrapolation theory. All of their numerical and real data calculating results shows that our theory and method are practical and efficient. Key words: prestack depth migration, generalized screen propagator, residual statics,inverse Q filter ,traveltime,3D seismic datum mergence
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The theory researches of prediction about stratigraphic filtering in complex condition are carried out, and three key techniques are put forward in this dissertation. Theoretical aspects: The prediction equations for both slant incidence in horizontally layered medium and that in laterally variant velocity medium are expressed appropriately. Solving the equations, the linear prediction operator of overlaid layers, then corresponding reflection/transmission operators, can be obtained. The properties of linear prediction operator are elucidated followed by putting forward the event model for generalized Goupillaud layers. Key technique 1: Spectral factorization is introduced to solve the prediction equations in complex condition and numerical results are illustrated. Key technique 2: So-called large-step wavefield extrapolation of one-way wave under laterally variant velocity circumstance is studied. Based on Lie algebraic integral and structure preserving algorithm, large-step wavefield depth extrapolation scheme is set forth. In this method, the complex phase of wavefield extrapolation operator’s symbol is expressed as a linear combination of wavenumbers with the coefficients of this linear combination in the form of the integral of interval velocity and its derivatives over depth. The exponential transform of the complex phase is implemented through phase shifting, BCH splitting and orthogonal polynomial expansion. The results of numerical test show that large-step scheme takes on a great number of advantages as low accumulating error, cheapness, well adaptability to laterally variant velocity, small dispersive, etc. Key technique 3: Utilizing large-step wavefield extrapolation scheme and based on the idea of local harmonic decomposition, the technique generating angle gathers for 2D case is generalized to 3D case so as to solve the problems generating and storing 3D prestack angle gathers. Shot domain parallel scheme is adopted by which main duty for servant-nodes is to compute trigonometric expansion coefficients, while that for host-node is to reclaim them with which object-oriented angle gathers yield. In theoretical research, many efforts have been made in probing into the traits of uncertainties within macro-dynamic procedures.
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An high-resolution prestack imaging technique of seismic data is developed in this thesis. By using this technique, the reflected coefficients of sheet sands can be gained in order to understand and identify thin oil reservoirs. One-way wave equation based migration methods can more accurately model seismic wave propagation effect such as multi-arrivals and obtain almost correct reflected energy in the presence of complex inhomogeneous media, and therefore, achieve more superiorities in imaging complex structure. So it is a good choice to apply the proposed high-resolution imaging to the presatck depth migration gathers. But one of the main shorting of one-way wave equation based migration methods is the low computational efficiency, thus the improvement on computational efficiency is first carried out. The method to improve the computational efficiency of prestack depth migration is first presented in this thesis, that is frequency-dependent varying-step depth exploration scheme plus a table-driven, one-point wavefield interpolation technology for wave equation based migration methods; The frequency-dependent varying-step depth exploration scheme reduces the computational cost of wavefield depth extrapolation, and the a table-driven, one-point wavefield interpolation technology reconstructs the extrapolated wavefield with an equal, desired vertical step with high computational efficiency. The proposed varying-step depth extrapolation plus one-point interpolation scheme results in 2/3 reduction in computational cost when compared to the equal-step depth extrapolation of wavefield, but gives the almost same imaging. The frequency-dependent varying-step depth exploration scheme is presented in theory by using the optimum split-step Fourier. But the proposed scheme can also be used by other wave equation based migration methods of the frequency domain. The proposed method is demonstrated by using impulse response, 2-D Marmousi dataset, 3-D salt dataset and the 3-D field dataset. A method of high-resolution prestack imaging is presented in the 2nd part of this thesis. The seismic interference method to solve the relative reflected coefficients is presented. The high-resolution imaging is obtained by introducing a sparseness- constrained least-square inversion into the reflected coefficient imaging. Gaussian regularization is first imposed and a smoothed solution is obtained by solving equation derived from the least-square inversion. Then the Cauchy regularization is introducing to the least-square inversion , the sparse solution of relative reflected coefficients can be obtained, that is high-resolution solution. The proposed scheme can be used together with other prestack imaging if the higher resolution is needed in a target zone. The seismic interference method in theory and the solution to sparseness-constrained least-square inversion are presented. The proposed method is demonstrated by synthetic examples and filed data.
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With the development of seismic exploration, the target becomes more and more complex, which leads to a higher demand for the accuracy and efficiency in 3D exploration. Fourier finite-difference (FFD) method is one of the most valuable methods in complex structure exploration, which keeps the ability of finite-differenc method in dealing with laterally varing media and inherits the predominance of the phase-screen method in stablility and efficiency. In this thesis, the accuracy of the FFD operator is highly improved by using simulated annealing algorithm. This method takes the extrapolation step and band width into account, which is more suitable to various band width and discrete scale than the commonely-used optimized method based on velocity contrast alone. In this thesis, the FFD method is extended to viscoacoustic modeling. Based on one-way wave equation, the presented method is implemented in frequency domain; thus, it is more efficient than two-way methods, and is more convenient than time domain methods in handling attenuation and dispersion effects. The proposed method can handle large velocity contrast and has a high efficiency, which is helpful to further research on earth absorption and seismic resolution. Starting from the frequency dispersion of the acoustic VTI wave equation, this thesis extends the FFD migration method to the acoustic VTI media. Compared with the convetional FFD method, the presented method has a similar computational efficiency, and keeps the abilities of dealing with large velocity contrasts and steep dips. The numerical experiments based on the SEG salt model show that the presented method is a practical migration method for complex acoustical VTI media, because it can handle both large velocity contrasts and large anisotropy variations, and its accuracy is relatively high even in strong anisotropic media. In 3D case, the two-way splitting technique of FFD operator causes artificial azimuthal anisotropy. These artifacts become apparent with increasing dip angles and velocity contrasts, which prevent the application of the FFD method in 3D complex media. The current methods proposed to reduce the azimuthal anisotropy significantly increase the computational cost. In this thesis, the alternating-direction-implicit plus interpolation scheme is incorporated into the 3D FFD method to reduce the azimuthal anisotropy. By subtly utilizing the Fourier based scheme of the FFD method, the improved fast algorithm takes approximately no extra computation time. The resulting operator keeps both the accuracy and the efficiency of the FFD method, which is helpful to the inhancements of both the accuracy and the efficiency for prestack depth migration. The general comparison is presented between the FFD operator and the generalized-screen operator, which is valuable to choose the suitable method in practice. The percentage relative error curves and migration impulse responses show that the generalized-screen operator is much sensiutive to the velocity contrasts than the FFD operator. The FFD operator can handle various velocity contrasts, while the generalized-screen operator can only handle some range of the velocity contrasts. Both in large and weak velocity contrasts, the higher order term of the generalized-screen operator has little effect on improving accuracy. The FFD operator is more suitable to large velocity contrasts, while the generalized-screen operator is more suitable to middle velocity contrasts. Both the one-way implicit finite-difference migration and the two-way explicit finite-differenc modeling have been implemented, and then they are compared with the corresponding FFD methods respectively. This work gives a reference to the choosen of proper method. The FFD migration is illustrated to be more attractive in accuracy, efficiency and frequency dispertion than the widely-used implicit finite-difference migration. The FFD modeling can handle relatively coarse grids than the commonly-used explicit finite-differenc modeling, thus it is much faster in 3D modeling, especially for large-scale complex media.
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The Second Round of Oil & Gas Exploration needs more precision imaging method, velocity vs. depth model and geometry description on Complicated Geological Mass. Prestack time migration on inhomogeneous media was the technical basic of velocity analysis, prestack time migration on Rugged surface, angle gather and multi-domain noise suppression. In order to realize this technique, several critical technical problems need to be solved, such as parallel computation, velocity algorithm on ununiform grid and visualization. The key problem is organic combination theories of migration and computational geometry. Based on technical problems of 3-D prestack time migration existing in inhomogeneous media and requirements from nonuniform grid, parallel process and visualization, the thesis was studied systematically on three aspects: Infrastructure of velocity varies laterally Green function traveltime computation on ununiform grid, parallel computational of kirchhoff integral migration and 3D visualization, by combining integral migration theory and Computational Geometry. The results will provide powerful technical support to the implement of prestack time migration and convenient compute infrastructure of wave number domain simulation in inhomogeneous media. The main results were obtained as follows: 1. Symbol of one way wave Lie algebra integral, phase and green function traveltime expressions were analyzed, and simple 2-D expression of Lie algebra integral symbol phase and green function traveltime in time domain were given in inhomogeneous media by using pseudo-differential operators’ exponential map and Lie group algorithm preserving geometry structure. Infrastructure calculation of five parts, including derivative, commutating operator, Lie algebra root tree, exponential map root tree and traveltime coefficients , was brought forward when calculating asymmetry traveltime equation containing lateral differential in 3-D by this method. 2. By studying the infrastructure calculation of asymmetry traveltime in 3-D based on lateral velocity differential and combining computational geometry, a method to build velocity library and interpolate on velocity library using triangulate was obtained, which fit traveltime calculate requirements of parallel time migration and velocity estimate. 3. Combining velocity library triangulate and computational geometry, a structure which was convenient to calculate differential in horizontal, commutating operator and integral in vertical was built. Furthermore, recursive algorithm, for calculating architecture on lie algebra integral and exponential map root tree (Magnus in Math), was build and asymmetry traveltime based on lateral differential algorithm was also realized. 4. Based on graph theory and computational geometry, a minimum cycle method to decompose area into polygon blocks, which can be used as topological representation of migration result was proposed, which provided a practical method to block representation and research to migration interpretation results. 5. Based on MPI library, a process of bringing parallel migration algorithm at arbitrary sequence traces into practical was realized by using asymmetry traveltime based on lateral differential calculation and Kirchhoff integral method. 6. Visualization of geological data and seismic data were studied by the tools of OpenGL and Open Inventor, based on computational geometry theory, and a 3D visualize system on seismic imaging data was designed.