773 resultados para 1522


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In this paper, we firstly give the nature of 'hypersausages', study its structure and training of the network, then discuss the nature of it by way of experimenting with ORL face database, and finally, verify its unsurpassable advantages compared with other means.

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采用3×3耦合器的光纤光栅激光传感系统(FBGLS)的波长解调结果依赖于3×3耦合器的物理特性,解调结果会因3×3耦合器三路输出的直流项、干涉条纹可见度和相位差参数的不稳定而发生一定程度的失真。理论推导给出了标定参数的方法并实现了计算机编程,能够在较大信号时实时给出标定结果,同时给出了相应的解调方案。计算机模拟发现采用上述方法消除了由3×3耦合器三路输出的参数不稳定带来的谐波,实验中解调结果的对比表明该方法带来一定程度的改善,和标准参考传感器测量结果有很高的相关性,此外基于该解调方案的光纤光栅激光传感系统具有较高的分辨率、动态范围和线性度。

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M2B5O9X: Re(M = Ca, Sr, Ba; X = Cl, Br; Re = Eu, Th) phosphors were synthesized via solid state method. The products were characterized with X-ray powder diffraction and luminescence spectrometer. The luminescent properties as well. as the influences of the matrix composition and other doping ions on the luminescence of the rare earth ions of the co-doped phosphors were investigated. The coexistence of Eu3+, Eu2+ and Th3+ were observed in these matrices. The phenomenon may be explained by the electron transfer theory. The sensitization of Ce3+ ion improves the intensity of emission of Eu2+, and Tb3+. The competition between electron transfer among conjugate rare earth ions and energy migration might be the reasons for the observation. We predict a novel trichromatic phosphor co-doped with Eu3+ Tb3+ in M2B5O9X.

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随着对海洋资源的开发,大量的海底工程设施应运而生,而对其依托的海底底床稳定性的研究就成为海洋地质和海洋工程学者当务之急的工作重点之一。不同的地质单元受控的海洋环境差异很大,海底底床的稳定性也表现出不同的特点,为此,针对不同的地质单元就需要选用不同的分析方法。本文选取以海底沙坝与海槽为主要地貌单元的青岛市汇泉湾海水浴场,以及沙脊和沙波广泛发育的南海北部湾西南海域浅海陆架两个典型海域作为研究区域。对于潮流和波浪碎裂流控制的海水浴场,通过采集表层样,借助流速仪、全站仪、激光粒度仪、DGPS定位,利用粒径趋势分析模型GSTA(Gao S,1996),结合地形测量数据和潮流数据,分析了海水浴场的表层沉积物粒度特征、沉积物类型、冲淤变化及输运方向;而对波浪潮流联合作用的北部湾西南浅海陆架采用多波束测深系统、DGPS定位等仪器测量手段,利用图像对比方法结合泥沙输运模型SEDTRANS(Michael Li, 2001),分析浅海陆架海底底床的地貌特点、地质单元类型、沙波底床的输运速率和方向、冲淤变化及底床稳定性对海底管线安全的影响。 采集并分析了青岛市汇泉湾海水浴场149个表层样品的粒度参数特征,结合沉积物输运趋势分析模型结果和水动力观测资料得出高潮线到沙坝沉积物输运方向为SE向,沙坝向海一翼沉积物输运方向为NW向;地形测量数据显示侵蚀区域主要分布在3月份沙坝脊线附近,而3月份槽线附近为主要的堆积区。 对比分析北部湾西南部海区2004~2006连续3年的多波束海底地貌扫描数据,得出研究区域海底沙波的波长为5.8~91.8m,波高0.1~4.3m,陡峭度0.013~0.12,对称指数0.32~6.52。沙波的移动速率最大达48.8m/a,移动方向在研究区域西部为SE向,中部呈往复迁移,东部为NW向;沙波不同部位的迁移速率不同,一般的沙波尾翼迁移速率较大;同一组沙波存在反向扭转迁移的现象,反向扭转迁移的轴线位于研究区域沙脊的脊线附近,这种反向迁移不仅与底层流作用有关,还与海底地形关系密切;04~06年西部海底底床处于侵蚀状态,局部的最大侵蚀量可达1.3m,东部处于堆积状态,最大堆积量达2.8m。 对于发育沙坝-海槽型潮上带和潮间带,粒径趋势分析模型结合地形测量以及水动力测量,分析底床冲淤变化及泥沙搬运方向,具有省时省力高效的优点,同时很好的弥补了粒径趋势分析模型对冲淤量的预测无能为力这一缺陷;对于沙脊沙波广泛发育的浅海陆架,通过对比多年的沙波地貌图计算沙波的迁移速率和方向,避开了通过潮流场模型预测沙波活动,因考虑底床稳定性的控制因素不足而带来的误差,为评价沙脊沙波型底床的稳定性提供新的可行性研究方法。

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In this paper, we determined the concentrations of antimony species (antimonite (Sb(III)), antimonate (Sb(V)) and dissolved inorganic antimony (DISb)) and arsenic, in Bohai Bay seawaters, as well as the relationships of the analytes with environmental factors such as seawater characteristics (e.g., suspended particulate material (SPM), salinity and total organic carbon (TOC)), heavy metals, nutrients and phytoplankton species, and evaluated the sources of arsenic and antimony. Dissolved arsenic and antimony concentrations in the surface waters were ranging spatially from 1.03 to 1.26 ng/ml and 0.386 to 1.075 ng/ml, with mean values of 1.18 and 0.562 ng/ml, respectively. Sb(V) as the prominent chemical species constituted about 89%. Regarding arsenic concentrations in the surface waters, there was a tendency for a small variation. However, antimony species concentrations were much variable than arsenic. The highest arsenic and antimony concentrations were found near the Haihe Estuary. These distribution patterns were controlled mainly by environmental factors, biological activities and sources. In this region, DISb and Sb(V) negatively correlated with salinity. Besides, arsenic and antimony correlated well with the nutrients, chlorophyll a and phytoplankton, implying that arsenic and antimony had been involved in biological cycling. In addition, according to our estimate, about 333.5 x 10(8) mg/year of arsenic and 454.2 x 10(8) mg/year of antimony reached Bohai Bay via rivers. (C) 2010 Elsevier Ltd. All rights reserved.

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As a fast and effective method for approximate calculation of seismic numerical simulation, ray tracing method, which has important theory and practical application value, in terms of seismic theory and seismic simulation, inversion, migration, imaging, simplified from seismic theory according to geometric seismic, means that the main energy of seismic wave field propagates along ray paths in condition of high-frequency asymptotic approximation. Calculation of ray paths and traveltimes is one of key steps in seismic simulation, inversion, migration, and imaging. Integrated triangular grids layout on wavefront with wavefront reconstruction ray tracing method, the thesis puts forward wavefront reconstruction ray tracing method based on triangular grids layout on wavefront, achieves accurate and fast calculation of ray paths and traveltimes. This method has stable and reasonable ray distribution, and overcomes problems caused by shadows in conventional ray tracing methods. The application of triangular grids layout on wavefront, keeps all the triangular grids stable, and makes the division of grids and interpolation of a new ray convenient. This technology reduces grids and memory, and then improves calculation efficiency. It enhances calculation accuracy by accurate and effective description and division on wavefront. Ray tracing traveltime table, which shares the character of 2-D or 3-D scatter data, has great amount of data points in process of seismic simulation, inversion, migration, and imaging. Therefore the traveltime table file will be frequently read, and the calculation efficiency is very low. Due to these reasons, reasonable traveltime table compression will be very necessary. This thesis proposes surface fitting and scattered data compression with B-spline function method, applies to 2-D and 3-D traveltime table compression. In order to compress 2-D (3-D) traveltime table, first we need construct a smallest rectangular (cuboidal) region with regular grids to cover all the traveltime data points, through the coordinate range of them in 2-D surface (3-D space). Then the value of finite regular grids, which are stored in memory, can be calculated using least square method. The traveltime table can be decompressed when necessary, according to liner interpolation method of 2-D (3-D) B-spline function. In the above calculation, the coefficient matrix is stored using sparse method and the liner system equations are solved using LU decomposition based on the multi-frontal method according to the sparse character of the least square method matrix. This method is practiced successfully in several models, and the cubic B-spline function can be the best basal function for surface fitting. It make the construction surface smooth, has stable and effective compression with high approximate accuracy using regular grids. In this way, through constructing reasonable regular grids to insure the calculation efficiency and accuracy of compression and surface fitting, we achieved the aim of traveltime table compression. This greatly improves calculation efficiency in process of seismic simulation, inversion, migration, and imaging.

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对湖南香花岭锡多金属矿床成矿早、晚两期方解石进行了系统的C、O、Sr同位素研究。结果表明,成矿早期方解石具有相对较低的δ^13 CPDB(-5.4‰~-1.4‰)、δ^18 OSMOW(+6.1‰~+13.9‰)和较高的^87Sr/^86Sr值(0.7101~0.7230);而成矿晚期方解石则具有相对较高的δ^13 CPDB(+0.2‰~+0.6‰)、δ^18 OSMOW(+19.4‰~+21.5‰)和较低的^87Sr/^86Sr值(0.7101)。分析认为,成矿早期方解石为岩浆热液与海相碳酸盐岩相互作用的产物,成矿流体中的碳源于岩浆碳和海相碳酸盐岩;模拟计算结果显示,成矿早期方解石为成矿溶液发生0.05~0.1摩尔分数的CO2去气作用的产物。而成矿晚期方解石主要为矿区碳酸盐岩低温淋滤的产物,流体中的碳主要源于矿区碳酸盐岩围岩。成矿流体中的Sr源于矿区花岗岩和碳酸盐岩,从成矿早期到晚期,岩浆来源的Sr逐渐减少,而碳酸盐岩围岩提供的Sr比例不断增大。

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Garrod, Brian, Leask, Anna and Fyall, Alan (2007) An assessment of ?international best practice? in visitor attraction management: does Scotland really lag behind? International Journal of Tourism Research, 9 (1), 21-42. RAE2008

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Ioan Fazey, John A. Fazey, Joern Fischer, Kate Sherren, John Warren, Reed F. Noss, Stephen R. Dovers (2007) Adaptive capacity and learning to learn as leverage for social?ecological resilience. Frontiers in Ecology and the Environment 5(7),375-380. RAE2008

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Tese de Doutoramento apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Doutor em Ciências Sociais.