92 resultados para Eddy covariance
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Anti-cyclonic eddies northwest of Luzon of the Philippines in summer-fall are identified in the merged data products of satellite altimeters of Topex/Poseidon, Jason-1 and European Research Satellites. The generation and propagation of the anti-cyclonic eddies, which are confirmed by satellite ocean color data, are found to be a seasonal phenomenon that is phase-locked to the onset of the southwesterly monsoon and the relaxation of the cyclonic wind curl in the northeastern South China Sea. The eddies originate from northwest of Luzon in summer, move across the northeastern South China Sea to reach the China continental slope in fall, and propagate southwestward along the continental slope in fall-winter, inducing shelfbreak current variations in the western South China Sea in fall-winter. The anti-cyclonic eddy discovered by Li et al. (1998) in the northern South China Sea is found to originate from northwest of Luzon and carry primarily the South China Sea waters. It does not appear to be an eddy shed from the Kuroshio in the Luzon Strait area as alluded by Li et al. (1998) and others.
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Analysis using historical data on the phosphate sources in Changjiang (Yangtze River) estuary show that phosphate was supplied equally from the east, south, west and north of the estuary. These sources include the Changjiang River, the Taiwan Warm Current (TWC), a cyclone-type eddy, and the 32A degrees N Upwelling, supplying different phosphates in different times, ways and intensities. The magnitude of their supplying phosphate concentration was related with the size in the order of the Changjiang River < the TWC < the 32A degrees N Upwelling < the cyclone-type eddy, and the duration of the supplying was: the Changjiang River > the TWC > the cyclone-type eddy > the 32A degrees N Upwelling. The four sources supplied a great deal of phosphate so that the phosphate concentration in the estuary was kept above 0.2 mu mol/L in previous years, satisfying the phytoplankton growth. The horizontal and vertical distribution of the phosphate concentration showed that near shallow marine areas at 122A degrees E/31A degrees N, the TWC in low nutrient concentration became an upwelling through sea bottom and brought up nutrients from sea bottom to marine surface. In addition, horizontal distribution of phosphate concentration was consistent with that of algae: Rhizosolenia robusta, Rhizosolenia calcaravis and Skeletonema, which showed that no matter during high water or low water of Changjiang River, these species brought by the TWC became predominant species. Therefore, the authors believe that the TWC flowed from south to north along the coast and played a role in deflecting the Changjiang River flow from the southern side.
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Mesoscale eddy plays an important role in the ocean circulation. In order to improve the simulation accuracy of the mesoscale eddies, a three-dimensional variation (3DVAR) data assimilation system called Ocean Variational Analysis System (OVALS) is coupled with a POM model to simulate the mesoscale eddies in the Northwest Pacific Ocean. In this system, the sea surface height anomaly (SSHA) data by satellite altimeters are assimilated and translated into pseudo temperature and salinity (T-S) profile data. Then, these profile data are taken as observation data to be assimilated again and produce the three-dimensional analysis T-S field. According to the characteristics of mesoscale eddy, the most appropriate assimilation parameters are set up and testified in this system. A ten years mesoscale eddies simulation and comparison experiment is made, which includes two schemes: assimilation and non-assimilation. The results of comparison between two schemes and the observation show that the simulation accuracy of the assimilation scheme is much better than that of non-assimilation, which verified that the altimetry data assimilation method can improve the simulation accuracy of the mesoscale dramatically and indicates that it is possible to use this system on the forecast of mesoscale eddies in the future.
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数值模式是潮波研究的一种有利手段,但在研究中会面临各种具体问题,包括开边界条件的确定、底摩擦系数和耗散系数的选取等。数据同化是解决这些问题的一种途径,即利用有限数量的潮汐观测资料对潮波进行最优估计,其根本目的是迫使模型预报值逼近观测值,使模式不要偏离实际情况太远。本文采用了一种优化开边界方法,沿着数值模型的开边界优化潮汐水位信息,目的是设法使数值解在动力约束的意义下接近观测值,获得研究区域的潮汐结果。边界值由指定优化问题的解来定,以提高模拟区域的潮汐精度,最优问题的解是基于通过开边界的能量通量的变化,处理开边界处的观测值与计算值之差的最小化。这里提供了辐射型边界条件,由Reid 和Bodine(本文简称为RB)推导,我们将采用的优化后的RB方法(称为ORB)是优化开边界的特殊情况。 本文对理想矩形海域( E- E, N- N, 分辨率 )进行了潮波模拟,有东部开边界,模式采用ECOM3D模式。对数据结果的误差分析采用,振幅平均偏差,平均绝对偏差,平均相对误差和均方根偏差四个值来衡量模拟结果的好坏程度。 需要优化入开边界的解析潮汐值本文采用的解析解由方国洪《海湾的潮汐与潮流》(1966年)方法提供,为验证本文所做的解析解和方文的一致,本文做了其第一个例子的关键值a,b,z,结果与其结果吻合的相当好。但略有差别,分析的可能原因是两法在具体迭代方案和计算机保留小数上有区别造成微小误差。另外,我们取m=20,得到更精确的数值,我们发现对前十项的各项参数值,取m=10,m=20各项参数略有改进。当然我们可以获得m更大的各项参数值。 同时为了检验解析解的正确性讨论m和l变化对边界值的影响,结果指出,增大m,m=20时,u的模最大在本身u1或u2的模的6%;m=100时,u的模最大在本身u1或u2的模的4%;m再增大,m=1000时,u的模最大在本身u1或u2的模的4%,改变不大。当l<1时, =0处u的模最大为2。当l=1时, =0处u的模最大为0.1,当l>1时,l越大,u的模越小,当l=10时,u的模最大为0.001,可以认为为0。 为检验该优化方法的应用情况,我们对理想矩形区域进行模拟,首先将本文所采用的优化开边界方法应用于30m的情况,在开边界优化入开边界得出模式解,所得模拟结果与解析解吻合得相当好,该模式解和解析解在整个区域上,振幅平均绝对偏差为9.9cm,相位平均绝对偏差只有4.0 ,均方根偏差只有13.3cm,说明该优化方法在潮波模型中有效。 为验证该优化方法在各种条件下的模拟结果情况,在下面我们做了三类敏感性试验: 第一类试验:为证明在开边界上使用优化方法相比于没有采用优化方法的模拟解更接近于解析解,我们来比较ORB条件与RB条件的优劣,我们模拟用了两个不同的摩擦系数,k分别为:0,0.00006。 结果显示,针对不同摩擦系数,显示在开边界上使用ORB条件的解比使用RB条件的解无论是振幅还是相位都有显著改善,两个试验均方根偏差优化程度分别为84.3%,83.7%。说明在开边界上使用优化方法相比于没有采用优化方法的模拟解更接近于解析解,大大提高了模拟水平。上述的两个试验得出, k=0.00006优化结果比k=0的好。 第二类试验,使用ORB条件确定优化开边界情况下,在东西边界加入出入流的情况,流考虑线性和非线性情况,结果显示,加入流的情况,潮汐模拟的效果降低不少,流为1Sv的情况要比5Sv的情况均方根偏差相差20cm,而不加流的情况只有0.2cm。线性流和非线性流情况两者模式解相差不大,振幅,相位各项指数都相近, 说明流的线性与否对结果影响不大。 第三类试验,不仅在开边界使用ORB条件,在模式内部也使用ORB条件,比较了内部优化和不优化情况与解析解的偏差。结果显示,选用不同的k,振幅都能得到很好的模拟,而相位相对较差。另外,在内部优化的情况下,考虑不同的k的模式解, 我们选用了与解析解相近的6个模式解的k,结果显示,不同的k,振幅都能得到很好的模拟,而相位较差。 总之,在开边界使用ORB条件比使用RB条件好,振幅相位都有大幅度改进,在加入出入流情况下,流的大小对模拟结果有影响,但线形流和非线性流差别不大。内部优化的结果显示,模式采用不同的k都能很好模拟解析解的振幅。
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本文使用1.5层约化重力准地转模式,研究了西边界流在西边界缺口处当处于迟滞过程(hysteresis)的临界状态时,其路径转变受中尺度涡旋影响的动力机制,探讨了中尺度涡旋影响西边界流在缺口处路径变化的几种形式。结果表明,气旋和反气旋中尺度涡旋都可能使西边界流产生由入侵状态到跨隙流态的转变,而只有反气旋中尺度涡旋才有可能诱发西边界流由跨隙流态向入侵流态的转变。论文进一步讨论了中尺度涡旋影响西边界流在缺口处路径变化,受涡旋强度,半径和位置的影响。 研究还显示当西边界流远离其迟滞过程临界状态时,其路径不容易受中尺度涡旋的影响而发生长期变化,此时西边界流会阻挡中尺度涡旋在缺口处的向西传播,并迫使涡旋在吕宋海峡东侧向北移动。以上结果用来解释了吕宋海峡黑潮变异的某些结构特征。
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菲律宾群岛以东的西太平洋赤道和热带海域以存在活跃和复杂的近表面环流而著称。北赤道流(North equatorial current)由东向西不断强化,当到达菲律宾群岛沿岸时,由于受菲律宾群岛的阻挡和β效应,海水在西边界堆积,在西边界形成两支强的西边界流,一支向北形成黑潮(Kuroshio current),一支向南形成棉兰老流(Mindanao current)。这两支西边界流对太平洋的热量重新分配将起着重要的作用。南下的棉兰老流到达棉兰老岛东南海域时,一部分成为印度尼西亚贯穿流(Indonesian throughflow),大部分转向东和苏拉威西海出来的海水及南赤道流(South equatorial current)越过赤道流进入这海域的海水混合,成为北赤道逆流(North equatorial countercurrent)。从1990年10月获得的水文资料算出本航次东边这条断面的纬向地转流断面图,可以看出,1990年晚秋北赤道汉分布在8°N以北的海域,强度最大的流集中在8~9°N之间相对狭窄的地带。而在76号站(3.41°N,128.76°N)到45号站(7.50°N,129.99°N)这条断面上,北赤道逆流分布在3°N~8°N之间,而强度最大流集中在靠近印度尼西亚的摩尔泰岛的南段,另从本航次获得的棉兰老岛以东海域-100米处动力米高度可以看出,在此海域存在两个气旋型涡旋(Cyclonic eddy)一个中心约在10.2°N,128°N,另一个中心在129°N以东,6.5°N左右的地方。用带~(63)Ni电子捕获检测器(ECD)的气相色谱对西太平洋的一些站在0米、50米、100米、150米、200米、300米等六层海水(有些站8~10层)中的氟里昴浓度进行了测定,发现在大部分站位位于300米以上的海水中氟里昴12浓度皆高于1.0 pmol·l~(-1)。表明表层温度混合层和温跃层之间的氟里昴-12交换的比较强烈,特别是靠近棉兰老岛的地方。用水下100米、200米氟里昴-12浓度等值线地域分布和变化,追踪北赤道流,棉兰老流,北赤道流之间的联系,结果与同一海域的动力米高度的地域分布十分吻合。再通过比较本航次东边这条断面的氟里昴-12浓度断面图和地转流断面图,我们能清楚地看的到,西向流区对应着高浓度的氟里昴-12分布,特别是在8~9°N流轴上面存在着氟里昴-12浓度最大值轴,而东向流区对应着相对低浓度的氟里昴-12分布,由以上结果,我们可以得出结论:用氟里昴示踪棉兰老岛以东海域的近表面环流是十分有效的,这样,氟里昴浓度在这海域的分布对今后建立本海域的大洋环流数学模式将能起重要作用。本文根据氟里昴主要来源是北半球的工业区,提出了一个氟里昴输入棉兰老岛以东海域的机制。
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We conducted 28 dilution experiments during August-September 2007 to investigate the coupling of growth and microzooplankton grazing rates among ultraphytoplankton populations and the phytoplankton community and their responses to habitat variability (open-ocean oligotrophy, eddy-induced upwelling, and the Mekong River plume) in the western South China Sea. At the community level, standing stocks, growth, and grazing rates were strongly and positively correlated, and were related to the higher abundance of larger phytoplankton cells (diatoms) at stations with elevated chlorophyll concentration. Phytoplankton growth rates were highest (> 2 d(-1)) within an eastward offshore jet at 13 degrees N and at a station influenced by the river plume. Among ultraphytoplankton populations, Prochlorococcus dominated the more oceanic and oligotrophic stations characterized by generally lower biomass and phytoplankton community growth, whereas Synechococcus became more important in mesotrophic areas (eddies, offshore jet, and river plume). The shift to Synechococcus dominance reflected, in part, its higher growth rates (0.87 +/- 0.45 d(-1)) compared to Prochlorococcus (0.65 +/- 0.29 d(-1)) or picophytoeukaryotes (0.54 +/- 0.50 d(-1)). However, close coupling of microbial mortality rates via common predators is seen to play a major role in driving the dominance transition as a replacement of Prochlorococcus, rather than an overprinting of its steady-state standing stock.
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The bottom sediment types in the Bohai Sea, Yellow Sea and East China Sea (BYECS) are diversified, and their distribution pattern is very complicated. However, the bottom sediment types can be simplified to be sandy sediment, clayey sediment and mixed sediment, which comprise the complicated distribution pattern of bottom sediment in the BYECS. The continental shelves of the BYECS are broad, with shallow water depths and tidal currents which are permanent and dominate the marine dynamics in the BYECS. Based on numerical simulation of tidal elevations and currents in the BYECS, the rates of suspended load transport and bed load transport during a single tidal cycle for sediments of eight different grain size ranges are calculated. The results show that any sediment, whose threshold velocity is less than that of tidal current, has the same transport trend. Suspended load transport rare, bed load transport rate, and the ratio of the former to the latter decrease with grain size becoming coarser and coarser. The erosion/accretion patterns of sediments with different grain sizes are determined by the sediment transport rate divergences, and the results show that the patterns are the same for sediments with different grain sizes. Three main bottom sediment types, i.e. sandy sediment mainly composed of fine sand, clayey sediment mainly composed of silty clay, and mixed sediment mainly composed of fine sand, silt, and clay, are obtained by computation. The three bottom sediment types and their distribution pattern are consistent not only with sediment transport field and the sea bed erosion/accretion pattern obtained by simulation, but also with field data of bottom sediment types and divisions. In the BYECS, sand ridges form mainly in the areas with strong rectilinear tidal currents, sand sheets form mainly in the areas dominated by strong rotatory tidal currents, and clayey sediments, i.e. mud patches, form mainly in the areas with weak tidal currents. Hence, not only the sandy sediments but also the clayey sediments in the BYECS are formed under the control of the whole tidal current field of the BYECS. The three main bottom sediment types are not isolated respectively-in fact, they constitute a whole tidal depositional system. Under the condition with no cyclonic cold eddy, the clayey sediments in the BYECS can form in weak tidal current environments. Therefore, a cold eddy is not necessary for the deposition of clayey sediments in the BYECS. (C) 2000 Academic Press.
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Detritus, as a nutrients reservoir, affects the trophic structure and dynamics of communities and supports a greater diversity of species and longer food chains. Detritivorous fish is an important organism to regenerate the nutrients from sediments. Despite the numerous studies on the nutrients cycle in fish, only a few attempts have been made to quantify the regenerating ability. In the present study, we chose the common detritivorous fish redeye mullet as the research object. Redeye mullet is also a common poly-culture fish in China. Diet, including a commercial diet mostly used in aquaculture and a home-made diet with contents close to detritus, was used and considered as a fixed factor. Temperature was also considered as a fixed factor as much research has shown that temperature has significant effects on fish metabolism. Moreover, body size was regarded as a covariate under analysis of covariance. Three key nutrients, namely carbon, nitrogen and phosphorus, were used to measure the nutrient-regenerating ability of redeye mullet under laboratory conditions. The results showed that the nutrient regeneration in percent of the consumption decreased with increasing temperature. Carbon and nitrogen regeneration of redeye mullet fed on commercial diet was lower than those of the home-made diet group, while the opposite was found for phosphorus. In each group, the amount of regenerated nutrients increased linearly with body size. Fed on the home-made diet, 5-g fish at 25 degrees C can regenerate 210.822 mg C, 37.533 mg N and 0.727 mg P per day.
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The impact of transient wind events on an established zooplankton community was observed during a, field survey in a, coastal region off northern Norway in May 2002. A transient wind event induced a coastal jet/filament intrusion of warm, saline water into our survey area where a semi-permanent eddy was present. There was an abrupt change in zooplankton community structure within 4-7 days of the wind event, with a change in the size structure, an increase in lower size classes less than 1 mm in equivalent spherical diameter (ESD) and a decrease in larger size classes greater than 1.5 mm in ESD. The slope of zooplankton biovolume spectra changed from -0.6 to -0.8, consistent with the size shifting towards smaller size classes. This study shows that even well established zooplankton communities are susceptible to restructuring during transient wind events, and in particular when wind forcing induces horizontal currents or filaments.
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在强非线性和复杂性的系统下,普通对称采样UKF 算法存在稳定性问题。为此,本文提出了基于状态方差阵对角相似分解的UKF 算法来保证算法的状态方差阵半正定。同普通对称采样UKF 算法比较,该算法降低了对状态方差阵的正定性要求。仿真试验验证了该方法的有效性。
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本文介绍了一种非接触式(LW-1型)机器人重复位姿精度检测系统.该系统采用电涡流传感器作为位置信息传感器.以这种传感器的检测性能为基础,研究设计了相应的传感器测量结构、数学模型和坐标变换求解方法,使系统技术指标及使用性能达到了检测机器人重复位姿精度的实用要求.该系统具有鲁棒性强、设计合理、结构简单、造价低廉等特点,可以满足我国现阶段在机器人学研究和机器人开发应用方面的需求
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There are four chapters in this dissertation. The first chapter briefly synthesizes the basic theories, methods and present-day applying situation of environmental magnetism. The second chapter probes into the magnetic mineral diagenesis in the post-glacial muddy sediments from the southeastern South Yellow Sea and its response to marine environmental changes, using the muddy sediment of Core YSDP103 formed in the shelf since about 13 ka BP. The third chapter illustrates the high-resolution early diagenetic processes by investigating the rapidly deposited muddy sediments during the last 6 ka in Cores SSDP-102 and SSDP-103 from the near-shore shelf of Korea Strait. The fourth chapter presents the results of detailed rock magnetic investigation of the surface sediments from the fine-grained depositional area on the outer shelf of the East China Sea in an attempt to provide environmental magnetic evidence for the provenance of the fine-grained deposit. Core YSDP103 was retrieved in the muddy deposit under the cold eddy of the southeastern South Yellow Sea, and the uppermost 29.79 m core represents the muddy sediments formed in the shelf since about 13 ka BP. The lower part from 29.79 to 13.35 m, called Unit A2, was deposited during the period from the post-glacial transgression to the middle Holocene (at about 6 ~(14)C ka BP) when the rising sea level reached its maximum, while the upper part above 13.35 m (called Unit Al) was deposited in a cold eddy associated with the formation of the Yellow Sea Warm Current just after the peak of post-glacial sea level rise. For the the uppermost 29.79 m core, detailed investigation of rock-magnetic properties and analyses of grain sizes and geochemistry were made. The experimental results indicate that the magnetic mineralogy of the core is dominated by magnetite, maghemite and hematite and that, except for the uppermost 2.35 m, the magnetic minerals were subject to reductive diagenesis leading to significant decline of magnetic mineral content and the proportion of low-coercivity component. More importantly, ferrimagnetic iron sulphide (greigite) is found in Unit A2 but absent in Unit Al, suggesting the control of marine environmental conditions on the magnetic mineral diagenesis. Magnetic parameters show abrupt changes across the boundary between the Unit Al and A2, which reflects a co-effect of environmental conditions and primary magnetic components of the sediments on the diagenesis. Alternating zones of high and low magnetic parameters are observed in Unit A2 of Core YSDP103, which is presumably due to periodic changes of the concentration and/or grain size of magnetic minerals carried into the study area. Cores SSDP-102 and SSDP-103, two studied sediment cores from the Korea Strait contain mud sequences (14 m and 32.62 m in thickness) that were deposited during the last 6,000 years. Analyses of grain sizes and geochemistry of the cores have demonstrated that the sediments have uniform lithology and geochemical properties, however, marked down-core changes in magnetic properties suggest that diagenesis has significantly impacted the magnetic properties. An expanded view of early diagenetic reactions that affect magnetic mineral assemblages is evident in these rapidly deposited continental shelf sediments compared to deep-sea sediments. The studied sediments can be divided into four descending intervals, based on magnetic property variations. Interval 1 is least affected by diagenesis and has the highest concentrations of detrital magnetite and hematite, and the lowest solid-phase sulfur contents. Interval 2 is characterized by the presence of paramagnetic pyrite and sharply decreasing magnetite and hematite concentrations, which suggest active reductive dissolution of detrital magnetic minerals, the absolute minimum abundance of magnetite is reached at the end of this interval. Interval 3 is marked by a progressive loss of hematite with depth, and at the base of this interval, 82% to 88% of the hematite component was depleted and the bulk magnetic mineral concentration was reduced to the lowest value in the entire studied mud section. Interval 4 has an increasing down-core enhancement of authigenic greigite, which is interpreted to have formed due to arrested pyritization resulting from consumption of pore water sulfate with depth. This is the first clear demonstration from an active depositional environment for a delay of thousands of years for acquisition of a magnetization carried by greigite. This detailed view of diagenetic processes in continental shelf sediments suggests that studies of geomagnetic field behavior from such sediments should be conducted with care. Paleoceanographic and paleoclimatic studies based on the magnetic properties of shelf sediments with high sedimentation rates like those in the Korea Strait are also unlikely to provide a meaningful signature associated with syn-depositional environmental processes. The rock magnetic properties of the surface sediments from the fine-grained depositional area on the outer shelf of the East China Sea, an area surrounded by sands, are investigated with a view to providing information on the sediment provenance. Multiple magnetic parameters such as magnetic susceptibility (%), anhysteretic remanent magnetization (ARM), saturation rernanent magnetization (SIRM), coercivities of SIRM (Her), and S ratios (relative abundance of low-coercivity magnetic minerals) are measured for all 179 surface samples, and partial representative samples are examined for their magnetic hysteresis parameters, temperature-dependence of magnetic susceptibility and x-ray diffraction spectra. Our research indicates that the magnetic mineralogy is dominated by magnetite with a small amount of hematite and is primarily of pseudo-single domain (PSD) to multidomain (MD) nature with a detrital origin. In the surface sediments, the granulometry of magnetic fractions is basically independent of grain sizes of the sediment containing the magnetic grains, and the composition of magnetic minerals remains almost homogeneous, that is, with a relatively constant ratio of low to high coercivity fraction throughout the area. The magnetic concentration in the study area generally decreases to the east or southeast accompanied by magnetic-particle fining to the east or to the northeast. The geographic pattern of magnetic properties is most reasonably explained by a major source of sediment jointly from the erosion of the old Huanghe River deposit and the discharge of the Changjiang River. The rock magnetic data facilitate understanding of the transport mechanism of fine-grained sediments in the outer shelf of the East China Sea.
Resumo:
The dissertation addressed the problems of signals reconstruction and data restoration in seismic data processing, which takes the representation methods of signal as the main clue, and take the seismic information reconstruction (signals separation and trace interpolation) as the core. On the natural bases signal representation, I present the ICA fundamentals, algorithms and its original applications to nature earth quake signals separation and survey seismic signals separation. On determinative bases signal representation, the paper proposed seismic dada reconstruction least square inversion regularization methods, sparseness constraints, pre-conditioned conjugate gradient methods, and their applications to seismic de-convolution, Radon transformation, et. al. The core contents are about de-alias uneven seismic data reconstruction algorithm and its application to seismic interpolation. Although the dissertation discussed two cases of signal representation, they can be integrated into one frame, because they both deal with the signals or information restoration, the former reconstructing original signals from mixed signals, the later reconstructing whole data from sparse or irregular data. The goal of them is same to provide pre-processing methods and post-processing method for seismic pre-stack depth migration. ICA can separate the original signals from mixed signals by them, or abstract the basic structure from analyzed data. I surveyed the fundamental, algorithms and applications of ICA. Compared with KL transformation, I proposed the independent components transformation concept (ICT). On basis of the ne-entropy measurement of independence, I implemented the FastICA and improved it by covariance matrix. By analyzing the characteristics of the seismic signals, I introduced ICA into seismic signal processing firstly in Geophysical community, and implemented the noise separation from seismic signal. Synthetic and real data examples show the usability of ICA to seismic signal processing and initial effects are achieved. The application of ICA to separation quake conversion wave from multiple in sedimentary area is made, which demonstrates good effects, so more reasonable interpretation of underground un-continuity is got. The results show the perspective of application of ICA to Geophysical signal processing. By virtue of the relationship between ICA and Blind Deconvolution , I surveyed the seismic blind deconvolution, and discussed the perspective of applying ICA to seismic blind deconvolution with two possible solutions. The relationship of PC A, ICA and wavelet transform is claimed. It is proved that reconstruction of wavelet prototype functions is Lie group representation. By the way, over-sampled wavelet transform is proposed to enhance the seismic data resolution, which is validated by numerical examples. The key of pre-stack depth migration is the regularization of pre-stack seismic data. As a main procedure, seismic interpolation and missing data reconstruction are necessary. Firstly, I review the seismic imaging methods in order to argue the critical effect of regularization. By review of the seismic interpolation algorithms, I acclaim that de-alias uneven data reconstruction is still a challenge. The fundamental of seismic reconstruction is discussed firstly. Then sparseness constraint on least square inversion and preconditioned conjugate gradient solver are studied and implemented. Choosing constraint item with Cauchy distribution, I programmed PCG algorithm and implement sparse seismic deconvolution, high resolution Radon Transformation by PCG, which is prepared for seismic data reconstruction. About seismic interpolation, dealias even data interpolation and uneven data reconstruction are very good respectively, however they can not be combined each other. In this paper, a novel Fourier transform based method and a algorithm have been proposed, which could reconstruct both uneven and alias seismic data. I formulated band-limited data reconstruction as minimum norm least squares inversion problem where an adaptive DFT-weighted norm regularization term is used. The inverse problem is solved by pre-conditional conjugate gradient method, which makes the solutions stable and convergent quickly. Based on the assumption that seismic data are consisted of finite linear events, from sampling theorem, alias events can be attenuated via LS weight predicted linearly from low frequency. Three application issues are discussed on even gap trace interpolation, uneven gap filling, high frequency trace reconstruction from low frequency data trace constrained by few high frequency traces. Both synthetic and real data numerical examples show the proposed method is valid, efficient and applicable. The research is valuable to seismic data regularization and cross well seismic. To meet 3D shot profile depth migration request for data, schemes must be taken to make the data even and fitting the velocity dataset. The methods of this paper are used to interpolate and extrapolate the shot gathers instead of simply embedding zero traces. So, the aperture of migration is enlarged and the migration effect is improved. The results show the effectiveness and the practicability.
Resumo:
Job Burnout has been a focus of the Occupational Stress Research. As a typical,helping occupation, teacher has attracted widely attention and researches in the areas of pedagogy and psychology. The special subgroup of teacher, headmasters who are the elites of the Basic Education, is ignored. The research about principals’ Job Burnout is nearly blank after analyzing related documents and information. With the development of the society, people pay more and more attention to the education and put more demands on the headmasters, especially middle-school principals. They are required not only to be good educators, who are equipped with all the inner qualities as a teacher, but also good managers. So the main purpose of this research was to compare the principal group with ordinary teacher group, and reveal underling factors, such as background variables and psychological protection variables. A representative sample of Wenzhou middle school principals sized 192 and a sample of middle school teacher sized 302 were sampled from various schools. The educational version of burnout inventory, self consistency scale, and interpersonal trust scale were administrated to the two samples, together with some demographic variables of interest. The applicability and equivalence of the three instruments used in this study were checked. Based on well-established reliability and cross-sample congruence of measures, the difference between principals and teachers was test. Then the contributing factors were analysis gradually. The five background variables were examined one by one in the two samples separately. A multiple covariance analysis was conducted to test whether there remained any difference between these two samples on the variables of interest. Regression analysis was used to further control the effect of self harmony and interpersonal trust to test the difference between two samples. Mediating analysis was conducted to build the relationship among the three constructs. The main results of the research were stated as following: 1. The internal consistency coefficients of all the scales were good, and no difference exited between the two groups. The measurement equivalence of three instruments was established well. The measures could be applied to and comparing the two samples. 2. The self-harmony, and interpersonal trust of principals were better than the ordinary middle-school teachers. Job Burnout of principals was significant lower than teachers. 3. Demographic variables like the gender, age groups, income levels, disricts, and the type of school, were important influencing factors. The difference patterns of the variables on these five variables in two samples had similarity and distinction. 4. After controlling the background variables, there remained significant difference between principals and teachers on the variables of interest. 5. Job Burnout negatively correlated with self-harmony and interpersonal trust. That is to say,the lower the degree of self-harmony and interpersonal are, the serious of the Job Burnout is, The correlation between the self-harmony and the interpersonal trust was positive. 6. After statistically controlling the background variables and psychological variables, there still exited significant difference between two groups of this study. Also, self harmony and interpersonal trust were significant protection predictors to different aspect of job burnout. 7. Mediating analysis was conducted to the residual score of the three constructs after controlling the five variables and group membership. Self harmony partially mediated the relationship between interpersonal trust and job burnout. That is, interpersonal trust had indirect effect to burnout mediated by self harmony, also had direct effect to burnout.