喀斯特原生天坑垂直梯度上植物多样性特征——以云南沾益天坑为例

规模宏大的地表负地形——喀斯特天坑具有巨大的容积和陡峭圈闭的岩壁,在坑底形成异于坑外的独特微生境,是研究物种组成和多样性的理想场所,但目前鲜少对喀斯特天坑植物群落的生态过程及其空间变化特征进行探讨。本研究以云南沾益大毛寺原生天坑植物群落为研究对象,通过游动分割窗技术以及边缘效应值、边缘效应强度和β多样性指数的计算,对原生天坑\"坑边缘—坑壁—坑底\"的生态交错带进行定量判定,探讨垂直环境梯度上植物群落物种多样性变化特征及天坑内外物种多样性边缘效应特征。研究结果表明,原生天坑\"坑边缘—坑壁—坑底\"垂直梯度上的生态交错带出现在坑壁中域位置,宽度大约为40 m,是连接天坑内外生态系统的一个特殊生态过渡带;天坑内外植物群落在坑壁出现\"断裂\",存在不同于一般生态交错带的\"边缘负效应\";基于β多样性指数,垂直环境梯度上植物物种更替率总体呈上升趋势,坑底与坑边缘的植物群落物种组成存在较大差异,坑底拥有更高的物种丰富度和多样性,具有重要的物种多样性保护库价值

Comparative study on community ecology of transition zone along Eucalyptus citriodora to Acacia confusa forest stands

近年来，外来树种桉树在我国大量种植，产生了巨大的经济效益，但同时，其速生性、较强的化感作用等特性，也带来一些负面的环境问题，评估桉树种植的环境生态影响成为当前林业生态研究的热点。目前大量的研究集中在桉树群落生态学上，而关于桉树与乡土树种过渡带的群落生态学的综合比较研究未见报道。 为此，本文针对无居民海岛柠檬桉（Eucalyptuscitriodora）林与台湾相思（Acaciaconfusa）林过渡带三种林分林下层植被群落生态、林分凋落物及其分解动态进行了研究，为外来树种桉树种植区的生态影响评估和生态防治提供科学数据。 林下层植被群落生态研究表明，三种林分林下层物种组成、多样性、地上生物量...Eucalyptus is one of exotic trees in our country, which has been extensively afforested in recent years. Though gaining enormous economic benefits, the plantation has brought some inverse environmental problems due to its biological characteristics of fast growth and allelopathy. Many researches currently have focused on the community ecology of Eucalyptus stands; However, the comprehensive compar...学位：工学硕士院系专业：海洋与环境学院环境科学与工程系_环境工程学号：2262008115155

Subduction Dynamics at the Northwestern Pacific Slab Edge: Constraints of Tomography in Kamchatka

Kamchatka is located at the northwestern edge of the Pacific plate. The Pacific slab is subducting into the mantle along the Kamchatka trench. Are there any differences in subduction features near the edge? To answer this question, seismic tomography was applied to 77,141 P-wave arrival times of 2239 local earthquakes and 75 teleseismic events recorded at 76 permanent stations to study the three-dimensional velocity structure to a depth of 700 km below Kamchatka. A clear high-velocity anomaly was evident beneath the study region, which is consistent with the distribution of intermediate-depth and deep-focus earthquakes. This high-velocity anomaly was interpreted as the subducting Pacific slab with its subduction angle and depth gradually increasing from the north to south along the Kamchatka trench. Another high-velocity anomaly appeared in the mantle transition zone and the uppermost lower mantle, which may reflect a piece of detached oceanic lithosphere due to melting of the subducting slab near the slab edge. Two slab windows were also found, through which hot mantle materials flowed from the subslab to the upper-mantle wedge. Large-scale low-velocity anomalies exist under the volcanic front, which reflect hot and wet upwelling flow in the mantle wedge due to the slab dehydration

Petrochemistry and mineral chemistry studies on metamorphic ultramafic rocks in Yanghou area, Zhenghe Country, Fujian Province, China

Petrochemistry studies indicate that the Yanghou metamorphic ultramafic rocksare composed of metamorphosed harzburgite and burgite and ultramafic cumulate . Trace element geochemistry and mineral chemistry studies on the metamorphosed harzburgite indicate that it is the relict of the depleted mantle. From systematic studies on petrochemistry , mineral chemistry and geochronology, it s concluded that the Yanghou metamorphic ultramafic rocks are components of Later Sinian-Early Paleozoic ophiolite in South China.岩石化学研究表明, 洋后变质超镁铁岩是由变质方辉橄榄岩和变质超镁铁堆积岩组成。变质方辉橄榄岩的微量元素地球化学及矿物化学特征表明, 应为亏损的残余地慢产物。通过系统的岩石地球化学、矿物化学及年代学研究, 认为洋后变质超镁铁岩可能为华南晚震旦一早古生代的蛇绿岩组成部分。published_or_final_versio

钻杆管体体积型缺陷的有限元分析

利用有限元软件 ,采用三维线性静态方法 ,对常用的 12 7mmIEU钻杆在常见的 11种蚀坑类型下的应力分布进行了计算。计算结果显示钻杆管壁常见蚀坑的应力集中系数在 1 5～2 5之间 ,拉伸和弯曲载荷作用下蚀坑应力分布基本一致 ,弯曲载荷的分析完全可以采用拉伸载荷结果来替代。对一系列的计算结果通过最小二乘法拟合出蚀坑应力集中系数随蚀坑深度和宽度的数学关系表明 ,拟合曲线与计算结果有非常好的一致

Preliminary study on the pollution characteristics of atmospheric particles over the offshore marine atmosphere

近岸海域是大气污染物从陆地向海洋迁移、扩散的过渡带，也是陆海相互作用的主要通道，各类污染物经过大气的长距离输送到达海洋上空，通过干湿沉降进入海洋，直接影响着海洋生态环境。海洋生态系统的变化也将对海洋和大气的相互作用产生反馈。近年来，近岸海洋大气复合型污染问题日益突出，细粒子颗粒物污染导致的能见度降低及其相关联的灰霾污染天气日益增多已成为海洋大气环境研究中亟待解决的一个重要问题。针对日益严重的大气污染，本项研究通过离线分析技术和实时在线分析等方法对近岸海域大气颗粒物中持久性有机污染物多氯联苯（PCBs）、含碳气溶胶、以及重金属等的理化特征及可能来源进行了探索研究，结果表明： 1、台湾海峡西岸东...Recently, human health and marine environment are threatened by the increasing pollutions over the offshore marine atmosphere, especially the haze pollution. To study the pollution characteristics, obtain their relative contribution ratios to the offshore marine atmosphere, off-line analyses like ion chromatography, gas chromatography combined with electron capture detector (GC-ECD) and on-line an...学位：博士后院系专业：海洋与地球学院_海洋化学学号：201317000

Novel Ensemble Analytic Discrete Framelet Expansion for Machinery Fault Diagnosis

小波变换被称为“数学显微镜“,它对机械信号的多尺度分析在机械设备状态监测和故障诊断领域发挥着重要的作用。然而传统二进小波变换在工程应用中存在一些显著的不足,如平移敏感性、小波尺度能量泄漏、固定的二进“频率？尺度“划分网格等。尤其是后者使得经典小波变换对处于二进网格过渡带的特征分析中产生不可避免的“盲区“。基于此,提出一种基于过完备小波紧框架的新式“时间-尺度“分析方法-衍生增强离散解析小波分析框架。该小波分析框架基于双树复小波变换进行构造,通过合理地选择双树复小波基函数,并将之应用于增广树形迭代滤波器组中生成近似解析小波包变换,通过对近似解析小波包变换的分析结果进行子空间重排和小波包尺度空间交叉结合,构造伪二进小波包隐框架。在多尺度分解的意义下,所提出的衍生增强离散解析小波分析框架(近似解析小波框架和伪二进小波包隐框架)很好地改进了经典小波存在时频表达能力方面的限制,有效地移动了小波尺度的中心频率,实现了自顶向下、多中心连续细化的“频率-尺度“分析网格。将之应用于的带钢精轧机的微弱故障特征提取中,验证了所提出方法对于经典小波分析方法的优越性。As the celebrated "mathematical scope", the multi-resolution analyzing capacity of wavelet transform(WT) plays an important role in condition monitoring and fault diagnosis of mechanical equipment.However, it has proven that the effectiveness of WT is hampered by several negative factors, such as shift-sensitiveness, significant energy leakage, and the fixed dyadic "frequency-sale" paving.Especially, the dyadic "frequency-sale" paving creates inevitable deficiency in identifying mechanical signatures located in transition areas of adjacent wavelet scales.A novel "time-sale" analysis methodology, named as derived ensemble analytic framelet(DEAF), based on overcomplete wavelet tight frame, is proposed.The DEAF is developed based on the existing dual tree complex wavelet transform(DTCWT).The DEAF starts from a selected DTCWT basis, and combines it with a hybrid augmented tree-structured filter-bank, which results in quasi analytic wavelet packet decomposition(QAWPD).With the results of QAWPT, an ensemble wavelet packet generating strategy is applied such that an unprecedented implicit wavelet packet tight frame(IWPTF) containing pseudo dyadic wavelet packets is obtained.With the combination of QAWPD and IWPTF, the proposed DEAF can be derived which possesses the "frequency-sale" paving characterized by continued time-frequency refinement of analysis centers.The proposed technique is applied to the mechanical signature analysis of an engineering application to validate its superiority compared with the existing methods.国家自然科学基金(51275382); 国家科技重大专项(2010ZX04014-016;2011ZX04003-021)资助项

下地壳及壳慢过渡带化学不均一性 -- 河北汉诺坝地区深源捕虏体元素地球化学证据

河北汉诺坝玄武岩中长英质麻粒岩、镁铁质麻粒岩和辉石岩捕虏体的主量元素和微量元素特征, 反映了下地壳及壳鳗过渡带组成具有高度化学不均一性。不相容元素原始地慢标准化曲线特征的差异表明捕虏体成因复杂。MgO 与不相容元素无或仅有很弱的相关性, 与相容元素的相关性则相对较明显。这些特征反映了下地壳及壳慢过渡带存在较强和多元的混合作用。捕虏体的加权平均值比基于麻粒岩地体资料估算的下地壳平均组成偏基性, 揭示了二者可能的成因差异。The major and trace element data of granulite and pyroxenite xenoliths, which are entrained in Hannuoba basalt Hebei Province, North China, suggest the highly chemical heterogeneity in the lower crust and crust-mantle transitional zone. There is no or only POor linear correlation between MgO and incompatible elements. Whereas a bit remarked correlations are observed between MgO and most compatible elements.The geochemical characteristics suggest that the strong and multiple mixing processes may have Occurred universally both in the lower crust and crust-mantle transitional zone. The weighed average composition of xenoliths shows a more mafic composition of the lower crust than that estimated from granulite data, which may imply the difference in the genesis.published_or_final_versio

The coupling of carbon and sulfur in sediments in the early diagenesis of methane hydrate potential area of northern South China Sea

天然气水合物作为21世纪理想的替代能源，成为了全球科学界的研究热点。天然气水合物在地层中能否稳定存在主要受温度、压力、自身结构以及成份组成的影响。海平面升降、底层水温变化、沉积速率的改变等自然环境的变化及海底滑坡、地震和火山爆发等地质灾害的发生都会引起天然气水合物的突发性分解释放。我国南海北部作为天然气水合物的潜在赋存区，在地质历史中也曾多次发生天然气水合物的分解释放。天然气水合物所分解释放的甲烷向上逸散，与沉积物中的硫酸盐发生氧化还原反应，甲烷厌氧氧化-硫酸盐还原反应（AOM-SR）是沉积物早期成岩过程中最重要的反应之一，其反应过程不仅受到沉积物中的有机质和向上逸散的甲烷等碳源的影响，沉积物...As an ideal alternative energy in the 21st century, gas hydrate has become a research focus in the global science field. The existing of gas hydrate is mainly under the influence of temperature, pressure and composition. Not only the variations of sea level, deposition rate and the sea water temperature at the bottom, but also sundry geological hazards, such as underwater landslides and earthquake...学位：理学硕士院系专业：海洋与地球学院_海洋地质学号：2242011115140