台风“麦莎”移动过程中水汽输送特征

利用NCEP1°×1°的再分析资料,用大尺度水汽通量流函数和速度势以及水汽收支对台风“麦莎”在移动过程中水汽输送流函数和速度势进行了分析。结果表明：台风“麦沙”在北上过程中,主要有2支水汽通道,一支是从太平洋开始向西经赤道到达印度洋,在索马里转向,经过孟家加拉湾呈西南气流向西北方向输送;另一支来自副高南侧偏东气流。计算分析还表明,用无辐散风流场来定台风中心要比用总的流场更精确。     

Relationship between North Pacific SST anomalies and the atmospheric circulation anomalies in January 2008

Based on the NCEP (National Centers for Environmental Prediction) data, the relationship between the Sea Surface Temperature Anomalies (SSTAs) in the North Pacific and the atmospheric circulation anomalies in January 2008 is analyzed in this study. The SSTA mode most correlated with the Geopotential Height anomalies (GHAs) in January 2008 in the North Pacific exhibited a basin-wide horseshoe pattern with a warm center in November 2007. This persistent SSTA pattern would induce positive GHAs in the Aleutian Low area and East Asia and the northward extension of the West Pacific Subtropical High in January 2008 by maximum diabatic heating in the atmosphere over the Kuroshio Oyashio Extension (KOE) area, leading to the occurence of the circumpolar trough-ridge wave train anomaly in January 2008.     

Iron Regulation of Wetland Vegetation Performance Through Synchronous Effects on Phosphorus Acquisition Efficiency

Iron-rich groundwater flowing into wetlands is a worldwide environmental pollution phenomenon that is closely associated with the stability of wetland ecosystems. Combined with high phosphorus(P) loading from agricultural runoff, the prediction of the evolution of wetland vegetation affected by compound contamination is particularly urgent. We tested the effects of anaerobic iron-rich groundwater discharge in a freshwater marsh by simulating the effect of three levels of eutrophic water on native plants(Glyceria spiculosa(Fr. Schmidt.) Rosh.). The management of wetland vegetation with 1–20 mg/L Fe input is an efficient method to promote the growth of plants, which showed an optimum response under a 0.10 mg/L P surface water environment. Iron-rich groundwater strongly affects the changes in ecological niches of some wetland plant species and the dominant species. In addition, when the P concentration in a natural body of water is too high, the governance effect of eutrophication might not be as expected. Under iron-rich groundwater conditions, the δ~(13)C values of organs were more depleted, which can partially explain the differences in δ~(13)C in the soil profile. Conversely, the carbon isotope composition of soil organic carbon is indicative of past changes in vegetation. The results of our experiments confirm that iron-rich groundwater discharge has the potential to affect vegetation composition through toxicity modification in eutrophic environments.     

Spatial patterns in natural Picea crassifolia forests of northwestern China,as basis for close-to-nature forestry

Close-to-nature forest management has been proposed as an effective method for improving the quality of plantation forests. Knowledge of spatial distribution patterns, structure, and succession trajectories in natural forests can provide guidelines for the establishment of close-to-nature forest plantations. Such knowledge is lacking in natural spruce(Picea crassifolia) forests in the Qilian Mountains of China, impeding the establishment of production forests. We conducted a case study in the Qilian Mountains to analyze the relationships between the naturally-formed forest patches and terrain factors, spatial heterogeneity of stand characteristics, and stand structure following harvesting disturbance. Our results suggested that spruce plantations will be effective on the N, NE, and NW slopes, at elevations between 2700 and 3300 m, and on slopes ranging from 15° to 45°. Further, planted forest patches should occupy 64% of the slope area on semi-shady slopes(NE, NW). Spatial patterns in the studied forest exhibited a strong scale-effect, and an area of 0.25 ha could be used as the most efficient plot scale for the management of spruce plantations. Partial logging is an effective method for the conversion of spruce planted forests into nearnatural forests, and the intensity of partial logging can be determined from the negative exponential function relationship between stand density and DBH. Our results provided critical information for the development of spruce plantations and conversion of existing plantations.     

马氏珠母贝育珠细胞小片和珠核处理技术研究Ⅳ:不同处理液在广西营盘育珠效果

通过广西营盘海区插核育珠试验,比较6组不同的细胞小片处理液及珠核处理液的育珠效果。结果表明:1)处理组手术贝休养期的平均死亡率仅3.9%,显著低于对照组(10.9%)(P<0.01),表明处理液具有促进伤口愈合、抗感染、提高成活率的作用;2)处理组休养期吐核率与对照组差异不显著(P>0.05),说明处理液对增加组织亲和力的效果不明显;3)除Y2处理组外,其余处理组育珠4个月的成活率平均为77.0%,比对照组高出7.0%～14.5%,且W组的单位收珠数量及珍珠品质等均优于对照组,表明W组处理液在促进珍珠质分泌、提高成活率、成珠率方面的作用优于对照组。比较分析处理组在海南陵水、广东徐闻及广西营盘3海区的育珠效果,优化筛选出2个优良匹配方案即小片处理液W0、Y3与核处理液C3匹配。W0、Y3两试验组在广西营盘海区进行中试,结果发现,休养期死亡率(8.0%、7.3%)显著低于对照组(11.7%)(P<0.05),育珠4个月的死亡率(19.7%、18.3%)显著低于对照组(31.7%)(P<0.05);育珠8个月的W0组的成活率为73.6%,成珠率为54%、优珠率为61.1%,分别比对照组提高约12%,表明筛选出的W0、Y3两优良匹配组同样适用于营盘海区的插核育珠处理,可提高育珠效果。     

利用神经网络建立GPS网络RTK的双差对流层误差模型

为减小对流层误差改正数中系统偏差的影响以提高对流层改正精度,提出了基于神经网络的顾及空间的对流层误差建模模型,该模型的对流层延迟误差改正在网内外精度均达5 cm。     

GPS软件接收机捕获方法研究

为解决GPS软件接收机中频信号的捕获问题,首先基于FFT的并行码捕获实现了对基带信号的粗捕,对粗捕的捕获判决进行改进,采用自适应门限值调整方法,即基于次高峰判决,同时对次高峰的寻找采用开窗原理;然后利用FFT的频域分析方法进行精捕。与传统相位差分精捕不同,利用FFT频域内对中频信号进行精捕,通过增大FFT变换的点数来提高精捕频率的分辨率,同时具体给出了粗捕和精捕的具体捕获步骤以及主要的技术问题;最后利用一组GPS实测数据对上述分析进行了计算,实验结果表明：基于FFT的GPS信号的粗捕与利用FFT的频域精捕方法非常有效,捕获快速准确,可以满足GPS软件接收机的要求。     

Higher species diversity occurs in more fertile habitats without fertilizer disturbance in an alpine natural grassland community

Are there some relationships among species diversity and soil chemical properties of high altitude natural grasslands？ Plant community composition and chemical properties of soil samples were compared to investigate the relationship between soil and species diversity, and the richness in Tibetan alpine grasslands. Results showed that species diversity was significantly positively related to soil organic matter （SOM）, total nitrogen （TN）, available nitrogen （AN）, total phosphorus （TP）, available phosphorus （AP）, and available potassium （AK） in the high alpine grasslands. Margalefs species richness index was also significantly positively related to SOM, TN, AN, and TP. Most soil chemical properties showed significantly positive correlation with species diversity and Margalef＇s richness index. Our results suggested that higher plant species richness index and diversity occurred in more fertile soil habitats in high altitude natural grassland community. In practice, fertilization management for the restoration of degraded grassland should be conducted with reference to the nutrient levels ofnatural grassland without the additional artificial fertilizer and with higher species-diversity and richness index.     

基于手绘图件的考古遗址三维建模方法

考古遗址是研究古代人类活动的重要场所。重建考古遗址三维模型对于历史回溯、古环境恢复和古迹保护等考古工作均具有重要的意义。传统考古发掘过程中普遍采用的手绘图件难以实现考古现场环境的模拟与再现,也不能准确地反映出遗址中文化层与其所包含地物的空间关系。近年来,考古学家引入各类勘察新技术用于考古文化层与遗迹的三维建模,但这些方法无法应用于已完成发掘工作的遗址三维重建。针对这一问题,本文提出一种以考古发掘过程中普遍采用的手绘图件为数据源的考古遗址三维建模方法。该方法以探方为基本建模单元,将考古文化层与遗迹分开建模,利用探方分布图及探方图建立考古文化层三维模型,利用遗迹图建立考古遗迹三维模型,并以三维实体布尔运算方法,将两者无缝整合,构建完整的田野考古遗址三维模型。最后,以湖南澧县八十垱东区为研究区,验证了本文相关研究成果的有效性与实用性。实践证明,该方法能够充分利用传统考古过程中积累的大量资料,有助于将传统考古学在宏观尺度下的定性描述转化为现代"数字考古"中微观尺度的定量描述。     

协同式电网规划系统设计

利用GIS技术进行电网管理和规划是实现电力信息化、建设数字电力的必由之路。论文在分析电网规划的特点基础上,将计算机支持的协同工作思想引入电网规划设计中,以ArcSDE GeoDatabase的版本操作和基于权限控制的数据表技术,作为空间数据协同操作和业务属性数据协同操作的技术基础,建立了协同式电网规划系统,系统的实践应用证明了系统的高效性和先进性。