查询词典 dune sand

The results show that: comparing the contrast community(formed by enclosure management for restoring vegetation naturaly on sand-dune for 7 years),some positive aspects of the artificial communities were showed as follows: 1 The level of the species diversity was more higher;2the vertical structure was so complicated that the surface of sand-dune was covered by multiple layers of plants;3 t...

结果表明：1利用植物再生沙障治理流动沙丘可以形成具有多物种、多层片、多层次垂直结构的沙障群落，其水平结构呈网格状沙障结构与障间小群落在空间上镶嵌互补，均衡分布的格局，具有很好的防风固沙和植被恢复效果；2再生沙障建植后第5年开始，沙障群落进入了衰退时期，适时采取科学的经营管理措施对于维持沙障群落的稳定，保障其效益的长期发挥是非常重要的。

Approximately 30,000 years ago, long on stable sand dune plant root, passes through the long time the decency, has formed the limestone, after the plant dies, the sand dune unceasing migration, causes these calcifications the limestone to reveal the surface, has formed the stalagmite which the present sees.

大约在3万年前，长在稳定的沙丘上的植物根部，经过长时间的风化，形成了石灰岩，植物死后，沙丘的不断移动，使这些钙化的石灰岩露出地表，形成了现在所看到的石笋。

In the fixed sand dune and half fixed sand dune in shallow groundwater, there are four districts among the soil from the underground watertable to the soil surface.

地下水埋深较大的固定半固定沙丘土壤含水量的总体变化趋势是由上到下逐渐增大。

Sedimentary facies model for mixed sediments of recent reefoid carbonates and siliciclastics is developed from the facies model of fringing and barrier reefs. Based on the sedimentary facies and textures, mixed sediments may be subdivided into 5 types as follows: 1 reef base mixed sedimentary rocks and reef framework mixed sedimentary rocks; 2 reef flat sand-gravel mixed sedimentary rocks; 3 backreef beach-dune gravel-sand mixed sediments; 4 backreef lagoonal sand mixed sediments ; and 5 reef front littoral sand mixed sediments.

礁源与陆源混合沉积相模式是从岸礁一堡礁相模式基础上发展而来，根据其沉积相和沉积结构特徵可以分为5种混合沉积：①礁基混积岩和礁格架混积岩；②礁坪砂砾屑混积岩；③礁后海滩－沙提砾砂屑混合沉积；④礁后泻湖砂屑混合沉积；⑤礁前浅海砂屑混合沉积。

The field experiments on the secondary flow developed on the lee side show that there are strong sand transport potential at the lee side of the dunes near the surface because of the decreasing of the sand grain size and the other factors. The transport directions are nearly vertical to the dune trends. Those factors and the sand slumping on slip face, and the sand transport processes on the stoss slope make the transverse dunes maintaining their morphology under the advance processes.

对沙丘背风坡发育的二次流的野外观测表明，近地面一定高度内沙丘背风坡气流仍有一定的强度，由于背风坡的沙丘沙粒径较小等因素，背风坡气流仍保持一定强度的输沙率，输沙方向与沙丘走向基本上垂直，这种作用与沙物质向背风坡崩落、迎风坡的输沙过程等共同作用，因而使横向沙丘在运动中保持其形态。

Whether sand can saltate from sand bed surface and quality of sand incipience are very important to the sand transport and the form of wind-blown-sand. The quality of sand incipience involved with many kinds of parameters, such as incipient velocity, incipient angle etc.

沙粒能否起动以及起动质量如何，如起动初速度、起动角度等参数都直接关系到沙粒的输运和风沙两相流形成。

So far, the main aspects studied include: the forecast of sand transport rate, the spatial distribution of sand and wind field, the mechanism of start and maintenance of sand transport, the development process of sand ripple, the influence of physical character of the sand bed on sand motion and so on.

目前的研究成果主要涉及到风沙输运的输沙率的预测、沙粒和风场的空间分布规律、风沙运动的起动机制和维持机制、沙波纹的产生和发展机制以及地表物理性质的改变对风沙运动的影响等。

Aiming at disjunction of microcosmic researches and macroscopical researches and status quo of theory basis researches of Aeolian sand movement near the sand bed, based on plenty of experiment data in wind tunnel, this thesis studies some microcosmic researches including the number of lift-off sand grains percent time percent sand bed area and relative movement parameters of saltating sand grains by combined methods of mechanical and statistical mechanical theories. Then, this thesis develops in advance a relation between the microcosmic researches and macroscopical researches in order to describe truly the theory model of some macroscopical physical variable of Aeolian sand movement.

本文针对当前风沙运动微观与宏观研究相脱节、准确描述近地面风沙运动规律的理论基础薄弱的现状，基于大量风洞实验数据，通过对沙床面单位时间单位面积起跳沙粒数、沙粒跃移运动过程中相关参数等微观问题的研究，力图建立风沙运动微观与宏观研究的联系桥梁，以期能够准确描述风沙运动宏观量变化的理论模型。

The results of calculations showed that the maximum increments in saltation height and horizontal distance due to the Magnus force were 10.2 and 24.9%, respectively, and that both increments increased with increasing lift-off angle. The maximum increments in saltation height and horizontal distance of sand grains caused by the Saffman force were only 4.6 and 3.7%, respectively. The vertical concentration distribution of Aeolian sand flow follows exponential function distribution whether or not force analysis of saltating sand grains includes Magnus and Saffman force. The effect of Magnus and Saffman force on the vertical concentration distribution of Aeolian sand current makes the rate decrease near sand bed and it is consistent with the effects of Magnus and Saffman force on the saltation height and distance of sand grains.

Magnus力对跃移高度和水平距离产生的最大增量分别可达到10.2%和24.9％，这两个增量均随起跃角度的增加而增大；Saffman力对跃移高度和水平跃移距离产生的最大增量分别为4.6%和3.7%；是否考虑Magnus与Saffman力，风沙流垂向质量百分浓度均服从指数函数分布，Magnus与Saffman力使得风沙流垂向质量百分浓度较不考虑它们的作用呈现出底层的比例较小，上层较大，Magnus与Saffman力对跃移高度的影响基本与其对风沙流垂向质量分布的影响一致，不过Magus力对风沙流垂向质量百分浓度分布影响较大，0-2cm范围内尤为强烈(7.16-10.81)，其他高度层(2-20 cm)的影响相对较小(0-2.95)。

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The user information management is to similarly the user information increase, deletes, renewal operation.

用户信息管理同样是对用户信息的添加，删除，更新的操作。

It is particularly well-known in China because of its association with Karl Marx.

我想，一个原因是大英图书馆作为世界最大的图书馆之一久负盛名，而且它与马克思的渊源在中国是众所周知。