全球多尺度空间数据模型研究

如何组织和管理分布式环境下全球海量(PB级以上)空间数据,进行全球多尺度空间剖分,建立高效的编码与索引机制,从而实现海量空间数据的高效调度与协同服务是网络3维虚拟地球平台中关键技术之一.对此,本文重点讨论了全球多尺度空间数据模型的建立,其核心是全球多尺度空间索引和多级金字塔模型的空间数据组织方法.最后基于开放式虚拟地球...     

一组RegCM4动力降尺度对中国群发性高温事件的模拟评估

基于高分辨率格点数据集CN05.1和区域气候模式RegCM4对4个全球气候模式动力降尺度模拟（CdR、EdR、HdR、MdR）,识别了观测和模拟的1981—2005年中国群发性高温事件（CHTE）。在此基础上,评估了模式对中国CHTE的模拟能力。结果表明：4个动力降尺度模拟以及多模式集合（MME）均能很好地模拟出中国CHTE频次、持续时间和累计强度的空间分布。不过,HdR模拟的CHTE发生次数在新疆地区略偏少,而其他3个模拟试验的CHTE次数在中国东南部略偏多。观测中CHTE持续时间、极端强度、累计强度、最大影响面积、平均影响面积、综合强度等的频率分布规律均能被合理再现。MME也能很好模拟观测揭示的CHTE综合强度以及频次、持续时间、强度、影响面积等单项指标的上升趋势。单模式成员亦可再现大多数指标的上升趋势,但也存在一定不足,如EdR模拟的CHTE综合强度呈减弱趋势,MdR模拟的CHTE频次和极端强度呈弱的下降趋势。     

Use of the National Drought Model (NDM) in Monitoring Selected Agroclimatic Risks Across the Agricultural Landscape of Canada

Abstract

The National Drought Model (NDM) is an amalgamation of the atmospheric component of the original Palmer Drought and Versatile Soil Moisture Budget (VSMB) models. The NDM uses locally derived coefficients from the station or gridded climate data to calculate a calibration factor for comparing locations in time and space. A modular approach is used to model major processes such as evapotranspiration, biometeorological time, snowmelt, and the cascading of soil moisture down to the root zone. The modular approach allows modifications to be made to specific sections without making structural changes to the entire model or the data inputs. The NDM is an operational tool, integrating data from the climate, soil, and plant sciences to monitor agroclimatic risks such as drought and excess moisture. In this paper, the capacity of the NDM to monitor extreme agroclimatic risks, such as drought and flooding of agricultural soils, was assessed. Using the Palmer Drought Severity Index component of the NDM, the mapping of the spatial extent and severity of the 2001 and 2002 droughts across Canada and the excess moisture conditions on the Canadian Prairies in 2010 agreed with other assessments. The validation study of soil moisture at two Alberta locations (Lethbridge and Beaverlodge) showed that the VSMB tracked the soil moisture flux in the root zone successfully in response to changing environmental conditions. The VSMB explained about 70 and 60% of the variance in observed soil moisture at the two respective locations.     

基于HEC-HMS模型的时间步长对次洪模拟的影响分析

运用HEC-HMS水文模型,初步建立了适用于晋江西溪流域的暴雨洪水模型。在此基础上,采用15 min和60 min两个模拟时间步长,研究模拟时间步长的变化对模拟结果的影响,进而寻求最佳的时间步长和模拟结果。结果表明:时间步长对模拟结果存在一定的影响,当改变时间步长时,需要通过参数的调整,才可得到相似的模拟结果,在其他参数不变的情况下,模拟时间步长减小,蓄量常数(K)呈逐渐增大的趋势。同时,当采用较短的模拟时间步长时,模型的模拟效率得到提高。     

基于变权组合预测模型探讨中国煤炭需求(英文)

变权组合预测是对各个单项预测模型在各时点上赋予适当权重进行组合,而权重是随预测时间变化的函数。该方法具有较高的预测精度和预测稳定性,能比较合理地描述系统的客观现实。本文依据1981-2008年的中国煤炭需求历史数据及对煤炭需求的影响因素,分别建立灰色系统、多元回归两个单项预测模型,构建了中国煤炭需求的变权组合预测模型,对中国未来12年煤炭需求进行了预测。     

用矩阵摄动法修改结构动力参数

作者应用模型简化技术中的矩阵摄动法来修改结构动力参数，从而避免了修改后结构动力参数的重计算，减少了系统仿真、分析和设计的计算量。算例表明，该方法有较好的计算效率。     

The association of poorly ordered graphite, coke and bitumens in greenschist facies rocks of the Poniklá Group, Lugicum, Czech Republic: the result of graphitization of various types of carbonaceous matter

Greenschist facies rocks of the Poniklá Group (Ordovician-Silurian), Czech Republic, contain several types of carbonaceous matter that differ in their morphology, texture, reflectance and Raman characteristics. The first type consists of large (up to 3 mm) irregularly bound particles of low reflectance (R_omin = 0.9%; R_omax = 5.6%). The area ratio of the 1585 cm^-1 to 1350 cm^-1 Raman peaks (1.08–1.17) indicates an intermediate degree of graphitization. The formation of this type of highly porous particle, displaying a texture reminiscent of regular or needle coke, is attributed to the thermal alteration of the amorphous (structureless) kerogen of the precursor sediments. The second type consists of lamellar particles up to 30 μm thick, which can be associated with the latter or can occur independently in white mica-rich laminae. This type is characterized by high bireflectance (R_omin = 0.6%; R_omax = 11.9%) and by lower ratios (0.70–0.82) of the Raman peak areas. These particles are interpreted as the product of solid-state, diffusion-controlled graphitization of a chemically homogeneous organic material, e.g. of graptolite periderms. The third type consists of isometric, up to 2 mm large, commonly fractured grains and fragments which mainly occur in quartz-rich laminae. In reflected light, the texture is either homogeneous or consists of various types of anisotropic mozaics. The Raman peak area ratios (0.75–1.14) indicate a highly variable degree of structural ordering. These particles are considered as the remains of metamorphosed bitumens, accumulated in the sandy laminae of the original sediments. The fourth type consists of small particles of carbonaceous matter (maximum length 25 μm, thickness 1-2 μm), which occur adjacent to crystal faces of white micas. This type is probably the product of epitaxial growth of graphite from the gaseous phase. The results of this work indicate that the differences in the degree of graphitization of the carbonaceous matter in low-grade metamorphosed rocks can be mainly related to the initial nature of the sedimentary organic matter and to its premetamorphic history.     

THE CONSTRUCTION OF SIMULTANEOUS OPTIMAL EXPERIMENTAL DESIGNS FOR SEVERAL POLYNOMIALS IN THE CALIBRATION OF ANALYTICAL METHODS

In this paper a criterion is described for the construction of experimental designs for the evaluation ofcalibration models in analytical chemistry.The proposed criterion seeks a compromise between theD-optimal designs for estimating the parameters of different polynomial models.A computer algorithmis presented for a sequential construction of experimental designs using the optimality criterion.Theperformance of the optimality criterion and the computer algorithm is elaborated for the problem ofdiscrimination between a first-to a third-degree polynomial for the calibration of analytical methods.Anexperimental design consisting of replicate measurements at five distinct levels equally spaced over thecalibration range proved a good solution.     

Bianchi Type-1 vacuum models in modified theory of general relativity

In this paper, the problem of spatially homogeneous and an isotropic Bianchi type-1 space time with perfect fluid distribution is considered in Barber's second theory of gravitation. To obtain determinate solutions, we have assumed the equation of statep= γρ, 0 ≤ γ ≤ 1. It is observed that the general fluid distribution degenerates isotropic vacuum model whenγ = 1 and Λ < 0. Further it is observed that the vacuum model obtained in case of γ = 0, ρ = 0 andΛ = 0, reduces to well known Kasner model in Einstein's theory. Some physical and geometrical aspects of the models together with singularities in the models are also discussed This revised version was published online in July 2006 with corrections to the Cover Date.     

企业财务预警分析模型及其运用

为规避财务危机 ,减少财务损失 ,企业应经常性地利用财务会计报告和其他相关经营资料 ,结合运用多变量分析模型和单变量分析模型 ,进行财务预警动态分析 ,充分发挥其监测、诊断、预控和矫正的功能 ,从而保证企业持续、健康、有效地经营。