12 resultados para 350405 Road and Rail Transportation

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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Invasive alien species have become one of the most serious environmental issues in the world. Data of taxon, origin, pathway, and environmental impacts of invasive alien microorganisms, invertebrates, amphibians and reptiles, fish, birds, mammals, herbs, trees, and, marine organisms in terrestrial, aquatic, and marine ecosystems of China were analyzed during 2001 and 2003, based on literature retrieval and field survey. There were 283 invasive alien species in China, and the number of species of invasive alien microorganisms, aquatic plants, terrestrial plants, aquatic invertebrates, terrestrial invertebrates, amphibians and reptiles, fish, and mammals were 19, 18, 170, 25, 33, 3, 10, and 5, respectively. The proportion of invasive alien species originated from America, Europe, Asia, Africa, and Oceania were 55.1, 21.7, 9.9, 8.1, and 0.6%, respectively. Methods for estimation of direct economic losses to agriculture, forestry, stockbreeding, fishery, road and water transportation, storage, water conservancy, environment and public facilities, and human health were established. Methods for estimation of indirect economic losses caused by invasive alien species to service functions of forest ecosystems, agricultural ecosystems, grassland ecosystems, and wetland ecosystems were also established. The total economic losses caused by invasive alien species to China were to the time of USD 14.45 billion, with direct and indirect economic losses accounting for 16.59% and 83.41% of total economic losses, respectively.

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陕北黄土丘陵沟壑区 ,生态环境脆弱 ,水土流失严重 ,作为环境脆弱带的山坡生产型道路 ,对加剧土壤侵蚀起着重要的作用 ,属等外路。人们并不很重视的山坡生产型道路却与农村生产运输、经济交流密切相关 ,其建设与维护具有重要意义。通过对延安黄土丘陵沟壑区山坡生产型道路侵蚀状况调查及对道路防蚀建设的经验 ,总结了现有山坡道路侵蚀现状、方式、影响因素 ,并从生物、工程两方面初步阐述防蚀措施的配置与设计

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As a high-sedimentation rate depocenter along the path of the Kuroshio Current, the southwesternmost part of the Okinawa Trough is a key area to understand the Kuroshio history and sediments transportation. A 34.17-m-long sediment core was obtained by the advanced piston corer of Marco Polo/IMAGES XII MARION DUFRESNE during the May 2005 from the Southern Okinawa Trough at site MD05-2908. The recovered sediments were analyzed by AMS C-14 dating, coarse size fraction (> 63 mu m) extraction and moisture content determination in order to study its sedimentation flux and provenance. The depth-age relationship of core MD05-2908 was well constrained by 17 C-14 dating points. The sediments span across the mid-Holocene (6.8 ka B.P.) and have remarkablely high sedimentation rates between 1.8 and 21-2 m/ka, which is well consistent with the modern observations from sediment traps. We identified five 70-200 a periods of abnormally rapid sedimentation events at 6790-6600 a B.P., 5690-5600 a B.P., 4820-4720 a B.P., 1090-880 a B.P., and 260-190 a B.P., during which the highest sedimentation rate is up to 21-2 m/ka. In general, the lithology of the sediments were dominated by silt and clay, associated with less than 5% coarse size fraction (a parts per thousand << 63 mu m). As the most significant sediment source, the Lanyang River in northeastern Taiwan annually deliver about 10Mt materials to the coastal and offshore region of northeast Taiwan, a portion of which could be carried northward by currents toward the study area. Therefore, we concluded that the 5 abnormally rapid sedimentation events may be related to intensified rainfall in Taiwan and thus increased materials to our study area at that time. However, a few extreme-rapid sedimentation events cannot be explained by normal river runoff alone. The large earthquakes or typhoons induced hyperpycnal discharge of fluvial sediment to the ocean may also act as a potential source supply to the Okinawa Trough.

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A geochemical study of Bohai Bay surface sediments was carried out to analyze the potential harmful element (PHE: Ge, Mo, In, Sn, Sb,Te, Tl, Bi and V) concentrations, transportation and deposition, enrichment factors and sources. Germanium, Mo, In, Sn, Sb, Te, Tl, Bi and V concentrations in the surface sediments were: 1.43-1.71, 0.52-1.43, 0.04-0.12, 2.77-4.14, 1.14-2.29, 0.027-0.085, 0.506-0.770, 0.27-0.63 and 70.35-115.90 mu g/g, respectively. The distributions of total PHE concentrations, together with sequential extraction analyses, showed that the PHEs were mainly due to natural inputs from the continental weathering delivered to the bay by rivers and atmospheric transportation and deposition. However, high Mo, Sb, Te, Bi and V occurred in non-residual fractions, suggesting some anthropogenic inputs in addition to the natural inputs. Besides sources, the distributions of PHEs were influenced by the coupling of physical, chemical and biological processes. Enrichment factor (EF) was computed for each site for each element in order to assess the polluting elements and the degree of pollution at each site. Results revealed that the EFs were generally lower than 1.0, particularly for Ge, Mo, In, Sn, Tl and V; however, the EFs were higher (>1.5), particularly for Sb, Te and Bi, revealing moderate contamination. (C) 2010 Elsevier B.V. All rights reserved.

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通过室内人工降雨+放水冲刷相结合的方法,对5个坡度(3~18°),5种雨强(1~3mm.min-1),5组放水流量(1.4~9.0kg.m-2.s-1)下的黄棉土土质路面和早熟禾植物路面进行了共60余场次试验,对比分析了植物路相对于土质路侵蚀过程差异及产水、减沙效果。结果表明:在放水冲刷条件下,植物路侵蚀率随放水历时降低,其过程可用对数函数描述;土质路面侵蚀率变化复杂。两类道路的放水流量与侵蚀强度均呈现幂函数变化,且植物道路表现出明显的防蚀作用。雨强增加引起径流量、侵蚀强度增加,土质路的增加快于植物路;坡度增大时,侵蚀强度增大,径流深则为植物路稳定,土质路有小幅增加。植物路相对土质路的减沙幅度为26.24%~47.22%,减少能力可用抛物线方程描述,但植物路较土质路面有利于产生径流,径流深增加幅度平均为58.7%~144.1%,由于径流的泥沙含量大大降低,道路的侵蚀产沙反而有一定降低。

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分子导线作为未来分子电子器件的重要组成部分,其合成,组装及电子传输性能研究是当今化学、物理、生物和微电子工程等领域里一个非常热门的研究课题。本论文在齐聚苯乙炔及齐聚苯乙炔一唾吩乙炔分子导线的合成、组装及电子传输性能研究方面进行了一些工作,主要成果有以下几个方面:一、官能化短链分子导线的合成与表征比较系统地合成不同端基,不同分子长度和不同主链结构的乙酞琉基官能化的齐聚苯乙炔类分子导线,以便比较系统地研究各种因素对这类分子导线的自组装及电子传输性能的影响。对所有合成的官能化分子导线进行了红外光谱、核磁共振氢谱和质谱表征以确定其结构。二、长链分子导线的合成与表征用溶液和固定相快速合成方法合成了一系列苯乙炔齐聚物及苯乙炔一(蜜份乙炔交替共聚齐聚物:1)采用简便的路线,用溶液和固定相方法快速合成出十二烷氧基取代的苯乙炔齐聚物,最一长达到了八聚体。(2)采用一条最简便的路线,用固定相方法快速合成了异丙基取代的苯乙炔齐聚物,最长达到了八聚体。(3)用溶液和固定相方法首次合成了苯乙炔一唾吩乙炔交替共聚齐聚物。(4)用一种新颖的“现场去保护/偶联”二倍速方案快速合成出十二烷氧基取代的苯乙炔齐聚物,最长达到了八聚体。该方案最大的优点在于无需分离出对空气敏感的芳香端炔化合物,从而简化了实验操作以及提高了产物的纯度。对所有合成的齐聚物进行了红外光谱、核磁共振氢谱、核磁共振碳谱和激光质谱表征以确定其结构。三、官能化分子导线的组装及电子传输性能研究(l)用STM和CP-AFM研究了合成的官能化分子导线在金基底的自组装行为,发现形成的自组装单层缺陷很少,而且自组装单层非常均一。(2)用电化学和导电原子力显微镜技术研究了上述官能化齐聚苯乙炔分子导线的电子传输性能,发现界面接触和分子长度对分子导线的电子传导能力有很大的影响,而链结构的影响则相对要小些。此外,我们还发现齐聚苯乙炔体系的电子传输衰减系数β值仅为0.19A-1,说明它是一类性能优异的分子导线侯选物。(3)通过量子化学计算,我们对实验结果进行了初步解释。

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针对黄土高原蓬勃发展的窖灌农业 ,提出3种水窖配置模式 :峁顶光头式 ;路旁葡萄串式和场、院、凹地单点式。为了高效利用水窖集蓄的雨水资源 ,文中推荐自压微灌、外动力加压微灌、坑灌和水肥穴灌等4种窖水高效利用技术。

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山坡生产型植物路建设带动沟坡开发是人们争取生存空间,缓和土地压力,建设生态农业的重要途径,也是现阶段农村经济发展的基础。根据现阶段农村建设能力和技术经济条件及实现山川秀美现实需求,提出了适合该地区植物路建设勘测设计方法与综合防护技术体系。

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Eu3+ narrow band emitting EL device with PPV, Alq(3) as hole and electron transportation layers has been prepared. The emitting layer, which consists of PVK, Eu(DBM)(3) and PBD is formed by spin-casting method. A maximum luminance of 52cd.m(-2) is achieved from the device.

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Population data which collected and saved according to administrative region is a kind of statistical data. As a traditional method of spatial data expression, average distribution in every administrative region brings population data on a low spatial and temporal precision. Now, an accurate population data with high spatial resolution is becoming more and more important in regional planning, environment protection, policy making and rural-urban development. Spatial distribution of population data is becoming more important in GIS study area. In this article, the author reviewed the progress of research on spatial distribution of population. Under the support of GIS, correlative geographical theories and Grid data model, Remote Sensing data, terrain data, traffic data, river data, resident data, and social economic statistic were applied to calculate the spatial distribution of population in Fujian province, which includes following parts: (1) Simulating of boundary at township level. Based on access cost index, land use data, traffic data, river data, DEM, and correlative social economic statistic data, the access cost surface in study area was constructed. Supported by the lowest cost path query and weighted Voronoi diagram, DVT model (Demarcation of Villages and Towns) was established to simulate the boundary at township level in Fujian province. (2) Modeling of population spatial distribution. Based on the knowledge in geography, seven impact factors, such as land use, altitude, slope, residential area, railway, road, and river were chosen as the parameters in this study. Under the support of GIS, the relations of population distribution to these impact factors were analyzed quantificationally, and the coefficients of population density on pixel scale were calculated. Last, the model of population spatial distribution at township level was established through multiplicative fusion of population density coefficients and simulated boundary of towns. (3) Error test and analysis of population spatial distribution base on modeling. The author not only analyzed the numerical character of modeling error, but also its spatial distribution. The reasons of error were discussed.

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Saprolite is the residual soil resulted from completely weathered or highly weathered granite and with corestones of parent rock. It is widely distributed in Hong Kong. Slope instability usually happens in this layer of residual soil and thus it is very important to study the engineering geological properties of Saprolite. Due to the relic granitic texture, the deformation and strength characteristics of Saprolite are very different from normal residual soils. In order to investigate the effects of the special microstructure on soil deformation and strength, a series of physical, chemical and mechanical tests were conducted on Saprolite at Kowloon, Hong Kong. The tests include chemical analysis, particle size analysis, mineral composition analysis, mercury injection, consolidation test, direct shear test, triaxial shear test, optical analysis, SEM & TEM analysis, and triaxial shear tests under real-time CT monitoring.Based on the testing results, intensity and degree of weathering were classified, factors affecting and controlling the deformation and strength of Saprolite were identified, and the interaction between those factors were analyzed.The major parameters describing soil microstructure were introduced mainly based on optical thin section analysis results. These parameters are of importance and physical meaning to describe particle shape, particle size distribution (PSD), and for numerical modeling of soil microstructure. A few parameters to depict particle geometry were proposed or improved. These parameters can be used to regenerate the particle shape and its distribution. Fractal dimension of particle shape was proposed to describe irregularity of particle shapes and capacity of space filling quantitatively. And the effect of fractal dimension of particle shape on soil strength was analyzed. At the same time, structural coefficient - a combined parameter which can quantify the overall microstructure of rock or soil was introduced to study Saprolite and the results are very positive. The study emphasized on the fractal characteristics of PSD and pore structure by applying fractal theory and method. With the results from thin section analysis and mercury injection, it was shown that at least two fractal dimensions Dfl(DB) and Df2 (Dw), exist for both PSD and pore structure. The reasons and physical meanings behind multi-fractal dimensions were analyzed. The fractal dimensions were used to calculate the formation depth and weathering rate of granite at Kowloon. As practical applications, correlations and mathematical models for fractal dimensions and engineering properties of soil were established. The correlation between fractal dimensions and mechanical properties of soil shows that the internal friction angle is mainly governed by Dfl 9 corresponding to coarse grain components, while the cohesion depends on Df2 , corresponding to fine grain components. The correlations between the fractal dimension, friction angle and cohesion are positive linear.Fractal models of PSD and pore size distribution were derived theoretically. Fragmentation mechanism of grains was also analyzed from the viewpoint of fractal. A simple function was derived to define the theoretical relationship between the water characteristic curve (WCC) and fractal dimension, based on a number of classical WCC models. This relationship provides a new analytical tool and research method for hydraulic properties in porous media and solute transportation. It also endues fractal dimensions with new physical meanings and facilitates applications of fractal dimensions in water retention characteristics, ground water movement, and environmental engineering.Based on the conclusions from the fractal characteristics of Saprolite, size effect on strength was expressed by fractal dimension. This function is in complete agreement with classical Weibull model and a simple function was derived to represent the relationship between them.In this thesis, the phenomenon of multi-fractal dimensions was theoretically analyzed and verified with WCC and saprolite PSD results, it was then concluded that multi-fractal can describe the characteristics of one object more accurately, compared to single fractal dimension. The multi-fractal of saprolite reflects its structural heterogeneity and changeable stress environment during the evolution history.