共查询到19条相似文献，搜索用时 843 毫秒
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南极数据管理是南极条约协商会议（ＡＴＣＭ）、南极科学研究委员会（ＳＣＡＲ）、国家南极局局长理事会（ＣＯＭＮＡＰ）共同关心并且一直关注的热点问题，也是以新的研究方式、先进的技术手段来积极促进国际南极研究发展的综合性问题。南极数据管理特别规划组在一些成员国和国际机构作出许多主动性努力的基础上把建立和开发南极数据目录系统（ＡＤＤＳ）作为建立和发展国际南极数据（信息）管理系统的首要基础建设加以规划。ＳＣＡＲ－ＣＯＭＮＡＰ南极数据管理联合委员会（ＪＣＡＤＭ）将全面组织和协调国际南极数据管理工作的发展和ＡＤＤＳ的实施。本文介绍了相关的国际背景，解析了南极数据管理国际框架的构成。在这个基本框架下，针对我国南极数据管理工作的现实情况进行了初部探讨，提出了便于付诸实际操作的若干方法，并阐述了相应的学术见解。 相似文献
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该论文为硕士学位论文 ,于 1999年 5月在中国科学院青海盐湖研究所完成。该论文采用 XRD、TG、DTA、显微照相和化学分析等方法研究明矾在等温 (空气气氛 )和非等温 (氮气气氛 )条件下的热脱水行为 ,并对明矾的生产工艺提出“两步脱水”的参考性建议。论文运用等温法研究明矾脱水后物相组成和脱水失重的关系 ,讨论明矾恒温脱水过程的机制 ,拟合各个脱水阶段所适用的动力学方程 ,并计算了相应的动力学参数。根据非等温的热分析曲线探讨了与热效应相对应的化学反应及每个脱水阶段的活化能。论文研究发现 ,明矾在脱水过程中存在着明显的“反… 相似文献
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采用 TG- DTG- DTA热分析技术研究了 N,N’-双 (3-氨丙基 )草酰胺合胴 ( )配合物在动态空气气氛中的热行为 ;用微分法 (Achar法 )和积分法 (Coats- Redfen法 )协同处理非等温 TG数据 ,通过对比热分解动力学参数 E和 ln A,提出了配合物第一阶段热分解动力学方程 :dα/ dt =Ae- E/ RT (1-α ) 2 及第二阶段热分解动力学方程 :dα/ dt=Ae- E/ RT(1-α) ;并由动力学补偿效应获得了 E和 ln A的数学表达式 相似文献
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采用惰性气体保护下的高温熔融反应及氮淬冷技术,制备了xLI2S·（1—X）B2O23玻璃。利用DSC量热法研究了玻璃的非等温晶化动力学,计算得到晶化活化能E,Avrami指数n及晶化热—△H等动力学参数。实验发现,xLi2S·（1—X）B2O3硫氧化物能在X≤0．45的区域形成玻璃,x=0．25玻璃组份具有最强的抗晶化能力,而x=0．45玻璃组份最易晶化。玻璃的晶化为一热激活过程,且主要由表面成核机理控制。玻璃晶化活化能在180—100μm颗粒范围有最大值,晶化热—△H与峰值温度Tp满足线性关系。 相似文献
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中国陆地区域气象要素的空间插值 总被引：181，自引：8，他引：181
在区域农田生态系统生产力模拟模型研究中，空间插值可以提供每个计算栅格的气象要素资料。然而，在众多的气象要素空间插值方法中，并没有一种适合每一个气象要素的普适的最佳插值方法。本文以全国７２５站１９５１～１９９０年整编资料中的旬平均温度和计算得来的６７５站的月乎均光合有效辐射日总量（ＰＡＲ）为数据源，选用了距离平方反比法（ＩＤＳ）、梯度距离平方反比法（ＧＩＤＳ）和普通克立格法（ＯＫ）等３种插值方法，进行了方法选取的探讨。交叉验证结果表明：３种方法中，温度插值的平均绝对误差（ＭＡＥ）的排序为ＩＤＳ＞ＯＫ＞ＧＩＤＳ，其值分别为２．１５℃、１.９０℃和 ｌ．３２℃；在作物生长季节（４－１０月），ＭＡＥ分别 ２０℃、１．９℃和 １.２℃ ，表明ＧＩＤＳ在温度插值方面更具实用价值；对于ＰＡＲ，ＭＡＥ的排序为ＯＫ＞ＧＩＤＳ＞ＩＤＳ，其值分别为 ０．８３ＭＪ／ｍ２、０７１ＭＪ／ ｍ２和 ０．４６ＭＪ／ｍ２，说明复杂的方法并不必然具有更好的效果。对这２个气象要素的空间分布特征分析表明：温度和ＰＡＲ的经、纬向梯度和高度梯度均具有明显的季节性变化特征；温度的纬向梯度有近似正弦曲线的较强的季节变化，表现为夏季高，而冬、春季低；温度的高度梯度年 相似文献
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本文用Ｍｅｉｓｓｎｅｒ公式、Ｂｒｏｍｌｅｙ公式、Ｃｈｅｎ公式、Ｐｉｔｉｅｒ公式及经作者改进的平均球近似（ＭＳＡ）方法对锂盐水溶液（最大浓度达２０ｍｏｌ／ｋｇ）的离子平均活度系数进行了计算和比较，结果表明改进后的ＭＳＡ方法的计算精度最高。另外，本文还应用改进的ＭＳＡ法，使用由单一电解质水溶液离子平均活度系数得到的参数，不用任何混合参数，预测了２９８．１５ｋ时ＬｉＣｌ＋Ｌｉ２ＳＯ４和ＬｉＣｌ＋ＫＣｌ水溶液的等温溶解度图．其结果与文献实验值基本一致。 相似文献
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本文对东南极拉斯曼丘陵出露的石榴斜长角闪岩中的角闪石进行了４０Ａｒ－３９Ａｒ年龄测定,分别得到角闪石视年龄１５８６Ｍａ、１０１１～１０８０Ｍａ、７６１Ｍａ和５２９～５８２Ｍａ,角闪石坪年龄１０３６Ｍａ和５５４Ｍａ,角闪石Ａｒ－Ａｒ等时线年龄１０１０Ｍａ,这些同位素年龄证据,首次完整地记录了该区所经历的几乎所有构造变质热事件,为近几年国内外地质学家关于该区构造变质热事件争论的焦点问题,即晚元古代的１０００Ｍａ格林维尔事件（Ｇｒｅｎｖｉｌｉａｎ）与早古生代的５００Ｍａ泛非事件（Ｐａｎ－Ａｆｒｉｃａｎ）孰轻孰重以及前者是否存在,提供了答案。角闪石的４０Ａｒ－３９Ａｒ年龄测定结果表明,拉斯曼丘陵地区经历了复杂的多期变质演化历史,其原岩可能形成于早－中元古代,占主导地位的应该是晚元古代的１０００Ｍａ格林维尔事件,而５００Ｍａ泛非事件则是晚期较强烈的变质热事件。 相似文献
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青藏高原4月—10月光合有效量子值的气候学计算 总被引：4，自引：0，他引：4
根据１９９４年４月～１０月青藏高原太阳分光辐射的实测资料，计算出太阳总辐射中，光合有效辐射（ＰＡＲ）所占比例η＝０．４３９±０．００９，ＰＡＲ每１Ｊ的能量含有４．４３μｍｏｌ的量子。在青藏高原的气候学计算中，可用下式估算旬平均的ＰＡＲ能量日总量ＨＰＡＲ（ＭＪ·ｍ－２ｄ－１）和量子日总量ＵＰＡＲ（ｍｏｌ·ｍ－２ｄ－１）：ＨＰＡＲ＝（０．３９９＋０．０３６ｌｇＥ＊）ＨＵＰＡＲ＝（１．７６８＋０．１５９ｌｇＥ＊）Ｈ式中Ｈ（ＭＪ·ｍ－２ｄ－１）为总辐射旬平均日总量，Ｅ＊＝Ｅ·Ｐ０／Ｐ，Ｐ０（ｈｐａ）为标准大气压，Ｐ（ｈｐａ）为测点大气压，Ｅ（ｈｐａ）为地面水汽压。 相似文献
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Governing industrial estates on Jakarta's periurban area: From shadow government to network governance 
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下载免费PDF全文 Delik Hudalah 《Singapore journal of tropical geography》2017,38(1):58-74
This article investigates the way in which periurban politics have mediated foreign direct investment relocations and facilitated the spatial restructuring of the Jakarta Metropolitan Area (JMA), one of the largest and fastest‐growing megaurban regions in Asia. We conducted a series of in‐depth interviews in Cikarang, the largest, most developed industrial estate corridor in the urban periphery of JMA. We identified institutional settings, power struggles and governance mechanisms underlying the industrial estate transitions in the past three decades. We found that periurban governance in JMA has resulted in poor infrastructure connectivity and tight interactor and inter‐regional competition. As global economic turbulence and decentralization policies restrict the effectiveness of privatization strategies, network strategies are trialled to promote sustainability and inclusiveness in JMA's industrial estates and towns. 相似文献
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五种潜在蒸散发公式在汉江流域的应用 总被引：9，自引：1，他引：8
以汉江流域14个测站1960-2009年逐日气象资料为数据源,采用FAO 56 Penman Monteith以及Hargreaves,Blaney Criddle,Thornthwaite,Hamon 4种温度法计算各测站逐日以及逐月潜在蒸散发量,利用反距离加权插值法得到流域面平均年潜在蒸散发量。以FAO 56 Penman Monteith结果为标准,与温度法年潜在蒸散发量计算结果进行对比,修正温度法计算公式的经验系数,分析修正公式在汉江流域的适用性。结果表明：参数修正前温度法计算结果存在较大误差,相对偏差最大可达41.34%。修正后计算结果相对误差明显减小,最大偏差小于0.1%,并显示出较好的变化趋势和峰谷一致性。修正后的Hargreaves公式与FAO 56 Penman Monteith公式相关性最好,相关系数达到0.94,其次为Hamon公式和Thornthwaite公式,最后是Blaney Criddle公式。 相似文献
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水文循环模拟中蒸散发估算方法综述 总被引：16，自引：0，他引：16
为选取基于水文循环估算蒸散发方法提供依据, 首先对常用水文模型中蒸散发估算方法进行回顾, 根据其物理机理的强弱性, 将水文模型中蒸散估算方法分为整体折算法和分类汇总法。当前水文模型中整体折算法占较大比重, 它们之间的差异有两点:一是潜在蒸散发估算方法不同;二是土壤干燥度折算函数不同;研究表明:由于水文模型存在不确定性及Penman-Monteith 方法具有较高资料要求, 致使模拟中使用该方法与使用其它简化经验公式相似或更差的水文循环模拟效果。所以对于不同水文模型, 如何选取与之复杂程度相兼容的潜在蒸散发估算方程和土壤干燥度折算函数来降低模型的不确定性需进一步讨论。在此基础上, 预估基于水文循环估算蒸散发方法朝着复杂机理化和简单实用化两个方向发展。 相似文献
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JERKER 《地理学报(英文版)》1990,(1)
When using hyphenated methods in analytical chemistry,the data obtained for each sample are given asa matrix.When a regression equation is set up between an unknown sample (a matrix) and a calibrationset (a stack of matrices),the residual is a matrix R.The regression equation is usually solved by minimizing the sum of squares of R.If the sample containssome constituent not calibrated for,this approach is not valid.In this paper an algorithm is presentedwhich partitions R into one matrix of low rank corresponding to the unknown constituents,and onerandom noise matrix to which the least squares restrictions are applied.Properties and possibleapplications of the algorithm are also discussed.In Part 2 of this work an example from HPLC with diode array detection is presented and the resultsare compared with generalized rank annihilation factor analysis (GRAFA). 相似文献
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The soil-freezing characteristic curve (SFCC), which represents the relationship between unfrozen water content and sub-freezing temperature (or suction at ice-water interface) in a freezing soil, can be used for understanding the transportation of heat, water, and solute in frozen soils. In this paper, the soil freezing process and the similarity between the SFCC of saturated frozen soil and soil-water characteristic curve (SWCC) of unfrozen unsaturated soil are reviewed. Based on similar characteristics between SWCC and SFCC, a conceptual SFCC is drawn for illustrating the main features of soil freezing and thawing processes. Various SFCC expressions from the literature are summarized. Four widely used expressions (i.e., power relationship, exponential relationship, van Genuchten 1980 equation and Fredlund and Xing 1994 equation) are evaluated using published experimental data on four different soils (i.e., sandy loam, silt, clay, and saline silt). Results show that the exponential relationship and van Genuchten (1980) equation are more suitable for sandy soils. The simple power relationship can be used to reasonably best-fit the SFCC for soils with different particle sizes; however, it exhibits limitations when fitting the saline silt data. The Fredlund and Xing (1994) equation is suitable for fitting the SFCCs for all soils studied in this paper. 相似文献
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The radiative transfer theory (RTT) describes the energy transport through a random heterogeneous medium, neglecting phase information. It provides an adequate framework for modelling high-frequency seismogram envelopes. For isotropic scattering and sources, the radiative transfer equation (RTE) has been formulated analytically and numerically simulated using Monte Carlo methods for acoustic and elastic media. Here, we derive an exact analytical solution of the RTE in 2-D space for the acoustic case, including anisotropic scattering for a anisotropic point-like impulsive source. For this purpose, we generalize the path integral method, which has been used before in the isotropic case, to take into account the anisotropy of both the source radiation pattern and scattering processes, simultaneously. Then we obtain a general solution, which is written in a closed form in the Fourier space. To illustrate the theoretical results, we compute the full space and time evolution of the specific intensity for an arbitrary case. We also compare the time traces computed from our general solution with cases in which the source and/or the scattering process are isotropic. The importance of taking into account both anisotropies simultaneously becomes obvious in our examples. We also show that at long lapse time, our example approaches the solution of the diffusion equation. 相似文献
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Sediment transport rates were estimated for two flood events on the cobble-bed Sainte Marguerite River in the Saguenay region, Canada. Morphologic methods were used to derive one set of estimates, and a combination of the Meyer-Peter and Muller equation with a dimensionless sediment transport ratio (after Dietrich et al. [Nature 340 (1989) 215]) was used to derive another set of estimates. Both sets of estimates give consistent results for the first event (which had a decade-scale return period), and for the second event (which was the largest flood on record and had a century-scale return period). The transport occurring during the second event was an order of magnitude greater than that occurring during the first event: despite this disparity in the transport intensity of the two events, the channel morphology remained qualitatively similar. The observed degree of channel stability is attributed to a change of channel pattern and the initiation of bed degradation following channel rectification in the 1960s. 相似文献
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A new method for computing synthetic seismograms 总被引：10，自引：0，他引：10
C. H. Chapman 《Geophysical Journal International》1978,54(3):481-518
Summary. The computation of theoretical seismograms for models in which the elastic parameters and density vary only with depth (in a plane, cylindrical or spherical geometry) reduces to the solution of an ordinary differential equation plus the evaluation of inverse transformations. In principle, the problem is straightforward. In practice, many techniques and approximations can be used at each stage and many combinations and variants are possible. In this paper, we discuss a new method of evaluating the inverse transforms. Any method can be used to solve the differential equation and we only discuss a few analytic approximations to illustrate the new method. The inverse transformations are a frequency and wavenumber integral. Essentially four techniques can be used to evaluate these depending on the order of integration and whether the wavenumber integral is distorted from the real axis. Three of these have been widely used, but the technique of evaluating the frequency integral first and keeping the wavenumber real is new. In this paper, we discuss some of the advantages of this combination. 相似文献
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城镇化发展阶段划分 总被引：34，自引：2，他引：32
Northam认为城镇化呈"s"型曲线发展,其过程可划分为三个阶段,这为众多研究证实和引用,但其阶段分界点长期缺乏严格的数学定义.运用高等数学方法,推演出城镇化"s"型曲线的Logistic增长模型关于时间变量t的方程表达式,并通过定性与定量分析,推导出该曲线的三个特征点及其数学表达式.对Northam城镇化发展阶段划分思想进行进一步的讨论,提出城镇化发展"s"型曲线上两个曲率最大点为城镇化三个阶段的分界点;验证了在拐点处城镇化发展速度最大加速度为零,之前速度逐渐加大,之后速度逐渐减小;给出了阶段划分点、拐点和第二阶段历时与平均速度的计算公式.选择日本和其他22个国家城镇化历史数据进行拟合分析,城镇化阶段划分结果与相关研究非常吻合,并且符合世界城镇化发展的总体趋势,还特别证明并指出2004年中国城镇化发展已经出现速度拐点,验证了模型推导的结果.最后讨论了该方法的适用性和局限性. 相似文献