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1.
郭锐  王愿昌 《水土保持通报》1991,11(1):44-48,53
本文以泾河流域出口站(张家山站)1952~1985年34年实测输沙量为原始数据,应用灰色系统理论,建立一套灰色动态模型群,对泾河流域1976~1985年10年减沙效益进行了分析。用水文法比较得到了理想结果,为计算较大流域减沙效益提供了新方法,并为较大流域的综合治理,水土流失预报提供了依据。  相似文献   

2.
滑坡灾害复杂性特征研究   总被引:1,自引:0,他引:1  
从系统论的角度出发,将滑坡灾害作为一个复杂的巨系统来进行研究,详细分析了滑坡灾害在存在意义和演化意义两个方面的复杂性特征。同时,从协同理论、分形分维、突变理论、人工神经网络与免疫系统以及空间信息技术综合集成等方面探讨了多学科在滑坡灾害复杂性方面的研究。滑坡灾害的复杂性研究可以在一定程度上促进人类对滑坡灾害整体行为和发展演化过程的研究与探索,同时也可以为滑坡灾害的防治评价和预测预报提供科学依据和辅助决策支持,在滑坡灾害及其相关地质灾害的防治中具有积极的作用,在滑坡灾害的防灾减灾中有着广泛的应用前景。  相似文献   

3.
区域经济的协调性   总被引:3,自引:0,他引:3       下载免费PDF全文
该文是关于区域经济协调发展研究方面一系列论文的引论。把自组织理论应用于区域经济研究,在描述中国区域经济格局和简要评述国内外研究情况的基础上,指出区域经济研究应特别强调协调性。从内容、运行机制和具体操作三方面对区域经济的协调性作了探讨。提出了二个区域经济协调原则:①在不公平程度不超出一定限度的条件下,力求有最高的效率。给出了评价区域经济不公平程度的指标——区域经济差距的概念和计弹方法。对中国区域经济差距作了初步实证分析。给出中国区域经济差距的界限为5.5~6.5倍;②以市场机制的自组织作用为基础,以政府干予的组织机制为条件,政府干予的组织作用应能创造这样一种条件:既能使市场机制的自组织作用的积极方面得到充分发挥;又能使市场机制的自组织作用的消极方面得到有效抑制。  相似文献   

4.
<正> 土地是一个多层次、多维因子构成的非常复杂的物质系统,其内部分异具有明显的过渡性和不确定性。因此,土地适宜性评价的结果(如适宜与不适宜、一等宜农地与二等宜农地)也具有相对性、模糊性,目前还没有绝对统一的定量评价指标,且当土地系统的复杂性增大时,土地评价的精确性就相对减小。神府东胜矿区位于陕北黄土高原和鄂尔多斯高原毛乌素沙地的综合过渡地带,矿区内黄土丘陵地貌和风沙地貌交错分布,风蚀、水蚀交替进行,土壤、植被区系成分复杂,这就决定了矿区土地系统的复杂性。因此,矿区的土地适宜性评价只有运用系统工程原理及模糊多层次综合评判法,才能科学准确地判定各地类的质量特征,评价其适宜性和适宜等级。  相似文献   

5.
This paper studied the development of no‐tillage by combining concepts of co‐creation of knowledge and actor‐network theory. Reconstructing the process of no‐tillage development in Switzerland has made it possible to show that no‐tillage development may be regarded as a dynamic process of co‐creation of innovation, where human and non‐human actors are building networks by reciprocally transforming and translating each other and the relations between them. This conceptualisation reveals that spread of no‐tillage requires fundamental transformations within the network of conventional plough‐tillage agriculture, including institutional arrangements, farm equipment, work organisation, concepts of agriculture and personal and professional identities. Against this background, the limited spread of no‐tillage—despite its economic and ecological advantages—can be explained by the fact that the required transformations are too radical for many agricultural actors. This conceptualisation also implies that policy interventions are not understood as top down measures that intend to induce one‐to‐one direct causal chains between knowledge and action of farmers, but as mediators in a complex process of reciprocal translations between farmers, experts and scientists, as well as many non‐human actors. We conclude that investigating processes of co‐creation of knowledge from the perspective of actor‐network theory is a promising complement to hermeneutic approaches to co‐creation of knowledge such as social learning. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

6.
新疆城镇体系分形研究   总被引:3,自引:1,他引:3  
史娟  王哲  陈宝燕 《水土保持研究》2007,14(2):315-317,321
运用分形模型对新疆城镇等级体系的规模和空间结构进行分析,得出了目前新疆城镇体系由于受到譬洲分布的影响,城镇等级规模结构松散,空间分布也十分分散的结论。根据新疆的发展状况,提出新疆必须加大城市间的合作与对外联系,开放城市,促进同中亚地区的经济合作,带动新疆的经济发展,最终形成基础设施完善,开放度高,等级结构规模合理的城镇体系。  相似文献   

7.
Influence of iron content in sewage sludges on parameters of phosphate availability in arable soils The use of iron salts for the P elimination in sewage plants is widely used. But it is not clear whether the P availability in arable soils is negatively influenced by iron compounds or not. The aim of the investigations was, therefore, to study the influence of two sewage sludges with a high and a low Fe content respectively on P sorption and phosphate concentration (Pi) in the soil solution after application of CaHPO4 or sewage sludge to 5 loamy and 4 sandy soils (pot experiments and 1 silty loam (field experiment)). Soils were analyzed 1, 6, and 13 months after P application. Sludge Gö contained 12 kg P and 65 kg Fe (t DM)—1 (P : Fe = 1 : 5.4) and sludge Sh 25 kg P and 39 kg Fe (t DM)—1 (P : Fe = 1 : 1.5). The basic P application was 60 kg P ha—1 (= 30 mg P (kg soil)—1 in the pot experiment, as sludge or as CaHPO4). P uptake by maize was determined in a separate pot experiment with a loamy soil and the same P application rate. The P sorption capacity remained similar in all soils after application of sludge Sh (P : Fe = 1:1.5) compared with soils without sludge, however, after application of sludge Gö the P sorption increased by 16% (0—59%). After application of sludge Sh the mean Pi concentration increased in loamy soils by 34% and in sandy soils by 15%. On the other hand the Pi concentration decreased after applying sludge Gö by 13% and 36% as compared to the controls of the respective soils. In the field experiment the Pi concentration of plots with a high P level (50 mg lactate soluble P (kg soil)—1) was also significantly decreased after application of 10 t sludge Gö (126 kg P ha—1) in comparison with triple phosphate. One month after the application of increasing amounts of sludge Gö (5, 10, 15 t DM ha—1) both the concentration of oxalate‐soluble Fe in the soil and the P sorption were increased. The elevated relationship between these two parameters was highly significant (r2 = 0.6 — 0.97). Plant uptake of P was less after application of sludge Gö than after application of sludge Sh and much less than P uptake from CaHPO4. Sewage sludges with a P : Fe ratio of 1 : 5 should not be recommended for agricultural use, as the P availability is significantly reduced. Iron salts should not be used for conditioning of sludges.  相似文献   

8.
[目的]探讨基于数量化理论Ⅲ的组合预测模型在滑坡变形组合中的适用性,为滑坡变形组合预测提供新的思路。[方法]选取GM(1,1)、支持向量机、BP神经网络及MC预测作为滑坡变形的单一预测模型,并利用数量化理论Ⅲ分析单项预测的相对误差区间的重要性,进而确定区间权重,再结合预测误差确定的组间权重,综合确定组合预测的权值。[结果]组合预测结果相对误差的平均值为1.1%,方差为0.16。[结论]组合预测较单一预测模型的预测精度及稳定性都有较大的提高。  相似文献   

9.
渭河咸阳段近代洪水沉积物粒度分形特征研究   总被引:2,自引:0,他引:2       下载免费PDF全文
对渭河咸阳段高漫滩沉积物的粒度分形进行了研究。首先确定沉积物粒度分布具有分形特征的无标度区,然后计算出分维数。在无标度区范围内相关系数R2均大于0.95,沉积物粒度平均分维值为2.12,说明沉积物粒度分布具有很好的分形特征。将分维值作为一种新的沉积物粒度分析参数,与其传统粒度参数如平均粒径、标准偏差(σ)、偏度(SK)、峰度(KG)进行比较,利用SPSS软件分析Pearson相关系数,得出粒度分维值与其平均粒径的相关系数为0.807,与其标准偏差的相关系数为0.707,与其峰度的相关系数为0.675,与其偏度的相关系数为0.112。分析结果表明,沉积物粒度分维值与其平均粒径、标准偏差、峰度呈现明显的正相关关系,与其偏度呈现出并不明显的正相关关系。  相似文献   

10.
抗冻胀刚性渠道衬砌层断面设计的探讨   总被引:1,自引:0,他引:1  
为找到渠道刚性衬砌层最优断面,作者从理论上进行了受力分析。结果表明:圆弧底U应为理论最佳断面;并在不同的地下水埋深情况下,给出了计算公式。而且在实践中证明了其正确性。  相似文献   

11.
为评估气候变化背景下横断山区的干旱时空演变特征规律,基于1961—2019年横断山区94个气象站逐月气象数据计算得到非平稳的标准化降水蒸散指数(NSPEI)表征气象干旱,并利用游程理论、单变量和多变量Copula方法,揭示干旱特征在不同重现期下的联合分布特征。结果表明:(1)横断山区发生干旱的频次在33%~80%,南部高于北部,对于不同干旱程度,轻旱比极旱高48%左右,重旱和极旱主要集中在南部,轻旱和中旱基本上在整个横断山区都发生过,但是依然南部高于北部。横断山区不同月尺度的干旱程度存在空间差异性。秋季和夏季的干旱程度小于冬季和春季,3月份的干旱程度要高于其他月份,干旱程度为20.97~38.10。(2)广义帕累托分布函数(GP)是干旱历时的拟合最优单变量分布函数,广义极值分布函数(GEV)是干旱烈度的拟合最优单变量分布函数,Gaussian函数是拟合效果最优的Copula分布函数。(3)干旱烈度的空间分布特征和干旱历时几乎一致,横断山区出现长历时、高烈度概率南部小于北部。大于10年一遇的干旱历时可以超过一年,大于50年一遇的干旱烈度可以达到100。空间分布上,横断山区北部呈现东西向分布,受到纬度影响,在中部和南部呈现南北向的分布主要受到纵向岭谷的地形制约。(4)干旱历时>10.07,干旱烈度>36.96的联合重现期>0.01,同现重现期<0.01,即联合重现期>预定重现期>同现重现期,联合重现期横断山区的中西部缘区和中南部的部分地区联合重现期高于横断山区的其他区域,同现重现期的空间分布与联合重现期相反。总体而言,从干旱频次上来看,横断山区总体上南部要高于北部,而干旱程度北部要高于南部,同时在不同的重现期下,北部干旱风险要高于南部,因此未来在干旱风险防范方面要关注到横断山区的北部地区。  相似文献   

12.
某高速公路边坡成因机制分析与稳定性评价   总被引:1,自引:0,他引:1  
在山区修筑高等级公路不可避免地进行深挖高填,会形成大量的高陡路基边坡或者路堤边坡。由于岩土体原有的地质环境平衡被打破,客观上为这些边坡的坍塌、滑动等地质灾害创造了地质条件。工程实践表明,在我国已修建的山区高等级公路中,几乎是“无路不坍、无路不垮”,特别是在雨季,公路的坍方、滑坡更为普遍。所以如何正确认识山区公路边坡的地质条件、结构特点、形成机制和正确评价边坡的稳定性,已成为我国山区高等级公路建设中的重大地质工程问题。以某高速公路的边坡为例,详细阐述了采用“地质与工程”充分结合方法,评价该边坡施工全过程的稳定性状况,并以此为基础,提出了有效的治理措施。监测结果表明,治理工程实施后,边坡的稳定性达到了高等级公路的设计要求。  相似文献   

13.
该文运用系统科学原理对县级水土保持规划的论证进行了探讨, 提出了运用整体性原理论证规划的系统观点, 用相关性原理论证规划的结合度;用有序性原理论证规划的层次结构;用动态性原理论证规划的进度安排;用分解综合原理论证规划的措施体系;用创造思维原理论证规划的先进性;用验证性原理论证规划的指标体系;用反馈原理论证规划的可操作性。  相似文献   

14.
灌区水资源高效利用调控理论与技术研究进展   总被引:2,自引:1,他引:2  
灌区水资源高效利用调控理论与技术研究,对提高灌区水、肥资源利用率,防止涝渍、盐渍灾害,控制农田面源污染,修复生态环境,促进农业节水与水资源可持续利用具有重大意义。该文在总结国内外研究成果的基础上,系统分析了灌区水资源高效利用调控理论和技术两方面的研究现状,并指出了该项研究需进一步探讨和解决的问题。  相似文献   

15.
Graph theoretic approaches have received increased interest recently in landscape planning and conservation in the terrestrial realm, because these approaches facilitate the effective modelling of connectivity among habitats. We examined whether basic principles of graph theory can be extended to other ecosystems. Specifically, we demonstrate how a network-based context can be used for enhancing the more effective conservation of riverine systems. We first show how to use graph theoretic techniques to model riverscapes at the segment level. Then we use a real stream network (Zagyva river basin, Hungary) to examine the topological importance of segments in maintaining riverscape connectivity, using betweenness centrality, a commonly used network measure. Using the undirected graph model of this riverscape, we then prioritize segments for conservation purpose. We examine the value of each of the 93 segments present in the Zagyva river basin by considering the conservation value of local fish assemblages, connectivity and the size of the habitat patches. For this purpose we use the ‘integral index of connectivity’, a recently advocated habitat availability index. Based on the results the selection of the most valuable habitat segments can be optimized depending on conservation resources. Because of their inherent advantage in the consideration of connectivity relationships, we suggest that network analyses offer a simple, yet effective tool for searching for key segments (or junctions) in riverscapes for conservation and environmental management. Further, although the joint consideration of aquatic and terrestrial networks is challenging, the extension of network analyses to freshwater systems may facilitate the more effective selection of priority areas for conservation in continental areas.  相似文献   

16.
空间4-SPS/CU并联机构的受力分析   总被引:4,自引:3,他引:1  
运用螺旋理论分析了一种具有三维转动和一维移动(沿Z轴)的四自由度(4-SPS/CU)并联机构的自由度,得出该机构为无过约束机构。采用传统的拆杆法对该机构的每个活动构件进行了静力学分析,得出了该机构的静力学平衡方程组,判定该机构的静力学平衡方程组中方程个数大于未知量个数(属超定方程组)。多余的方程个数就是该机构的局部自由度,并采取去掉局部自由度对应的静力学平衡方程来求解该超定方程组。通过求解该方程组,得出了该机构每个构件上的全部约束力/力矩,并分别得出了驱动力与主运动副以及恰约束从动支链的约束反力随该机构位姿变化的仿真曲线。证实了该机构比无恰约束从动支链的四自由度并联机构拥有更好的承载能力。研究结果可为该机构在工程中的应用与结构设计提供静力学理论分析的参考。  相似文献   

17.
The increasing demand for improved large‐scale thematic maps of soil properties for use in such areas as hydrological modeling and landscape planning requires the inclusion of external information in the computerized construction of soil maps. As this data is often purely qualitative, regionalization methods are called for, that permit consideration of uncertain empirical information. A method based on fuzzy‐set theory is presented, which enables a GIS‐based quantification of soil properties with no loss of content input when transforming ”︁soft” data. This approach, which is also applicable to other tasks, is demonstrated by the construction of maps of soil properties based on uncertain qualitative information from the Hessian Forestry Survey and the small‐scale soil map of Hesse (1:50.000). Quality and uncertainty can be judged from a separate map of uncertainty indices. The thematic output map of the available water capacity of the rooting zone in the Dietzhölztal (Hesse) research site prepared using the fuzzy approach provided an increase of 101 % in spatial resolution compared with the 1:50.000 soil map.  相似文献   

18.
[目的]揭示川东红层岩质滑坡稳定性的影响因素,为该地区滑坡的防治提供理论依据。[方法]基于对川东红层地区的滑坡综合调查,利用数量化理论Ⅲ对该地区滑坡的影响因素及其耦合作用进行分析。[结果]川东地区滑坡的主要作用因素为岩层倾角、滑坡高度及临空面高度,次要作用因素为土地利用情况及岩层组合关系,而一般作用因素是外营力及人类工程活动和岩层时代;确定出年降雨量、侏罗纪时代岩层、小于50m的滑坡高度、岩层倾角在5°~15°之间、厚层砂岩或泥岩夹薄层泥岩或砂岩、临空面高度在5~15m之间、土地旱地利用及河流冲刷及人类工程活动的主控影响因素。[结论]在不同滑坡样品中,不同因素的耦合强度具有一定的差异。经对比分析结果与现场调查的可靠性验证,证明了该方法的有效性。  相似文献   

19.
Conservation planning is often based on static mapping of species’ ranges or habitat distributions. Succession and disturbance alter, however, habitat quality and quantity through time especially under global climate and land use change scenarios; hence, static protected areas may not ensure habitat persistence and species survival. Here, we examined the relative merits of static and dynamic (floating) protected areas for the conservation of American marten (Martes americana) habitat in a dynamic boreal forest of Québec (Canada). Forest dynamics were modeled using a spatially-explicit landscape disturbance model and protected areas were selected based on the quality and compactness of marten home ranges using MARXAN. Static protected areas were fixed in space during 200 year simulations of boreal forest dynamics, while dynamic protected areas were re-located every 50 years to track dynamic habitat. Dynamic protected areas supported more high quality home ranges through time than static protected areas. The locations of dynamic protected areas were constrained, however, by the highly fragmented forest patterns created through logging and fire in unprotected areas. Our findings emphasize the often-overlooked point that if dynamic conservation planning is to be successful in the long term, the landscape matrix quality surrounding protected areas must be managed in such a way that options remain when it comes to re-planning.  相似文献   

20.
土体由于赋存条件的不同而具有空间变异性,波动范围(Scale of Fluctuation,简称SOF)是描述土性参数空间变异性的重要指标,其数值对岩土工程的可靠度分析与设计具有重要影响。当前常用的求解土性参数波动范围的方法是随机场法与地质统计学方法。本文基于公式推导及实例运算,对比分析了随机场法中自相关函数、地质统计学法中半变异函数及其对应SOF值异同点,探讨了数据的趋势性、拟合参数初值、拟合点个数等因素对土性参数波动范围计算结果的影响。指出在地质统计学方法中对半变异函数(Semi-Variogram Function,简称SVF)进行曲线拟合时,应先对SVF估算值进行归一化处理;并提出了同时适用于随机场法与地质统计学法的确定拟合参数初值及拟合点个数的统一方法。在此基础上,以某工程的非饱和黏土为研究对象,在试验研究的基础上计算分析了土体物理性质参数及水力参数的波动范围。  相似文献   

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