查询词典 sand-dune

A thermal expansivity test device consisting of hating unit, attemperating unit, displacement transducer, recorder and so on, was developed to determine the thermal expansivity of new sand, clay-beaded sand, sodium silicate sand, resin bonded sand with the temperature or isothermally.

摘要铸造用砂热膨胀性测试装置，由加热装置、温控装置、移位传感器、记录仪等组成，可实现铸造用原砂（亦可用于粘土型砂、水玻璃型砂、树脂型砂等）的随温和等温热膨胀性测试。

Therefore it is necessary to research the mechanism of greensand used for high compacted molding methods thoroughly.This subject is one section of the National Natural Science Foundation subject ""Ivestigation on Predicting Method and Mechanism of Springback for High Compacted Sand Molds"", followed of the other completed one named ""Research on Microdeformation of Molding Sand"". A serious of experiments has been done on the reequipped three axial machine under certain technological conditions, and the mechanics, material science, rheologic science. It is systematically studied that the influences on the springback of sand mold were caused by the main influence factors: pressure, compacted rate and the content of soil. Through the analyzed experiments' data, the experienced stress-strain relationship concerning the main influence factors were obtained;under different technical parameter, the springback and spingback's potential energy are compared, the differences and indifferences between them are found out, and the springback's mechanism is discussed;according to the tests' data of YangGuoping coming from Tinghua University, experienced formula of molding sand's springback displacement is induced, the displacement and springback are compared, the margin of error's reasons are analyzed, and they are tested and verified mutually.

本课题为国家自然科学基金项目"高紧实度砂型预测方法及回弹机理的探讨"的一部分，是已结题的国家自然科学基金项目"铸造型砂微变形的研究"的后继，运用力学、材料学及流变学理论，利用改装的三轴仪，在一定的工艺条件下，作了大量系列实验，系统的研究了压实比压、紧实率和膨润土含量对砂型回弹的影响；对实验数据进行了分析和处理，得出了型砂关于压实比压、紧实率和膨润土含量的本构关系的经验公式；把各工艺参数下的型砂产生的回弹量与回弹势能进行比较，找出两者存在的异同点，并对回弹机理进行了探讨；通过清华大学杨国平的实验数据，推导出型砂回弹位移场的经验公式，并与实验测出的回弹量进行比较，分析误差造成的原因，并互相进行了验证。

In order to draw a circle around coarse sand concentrated coming area in sediment-laden and coarse sand area of the middle Yellow River,the paper makes macro analysis on the factors of geological structure,lithology of stratum,category of landforms and hydrometeorology of the sediment-laden and coarse sand area in the middle Yellow River and regional difference related with coarse sand production.

为在黄河中游多沙粗沙区确定粗泥沙集中来源区，从黄河中游多沙粗沙区地质构造、地层岩性、地貌类型、水文气象等因素与产粗泥沙关系的区域差异对粗泥沙集中来源区进行了宏观判析，认为在黄河中游多沙粗沙区范围内，吴旗—志丹—延安—延长一线以北、东胜—准格尔—清水河一线以南、吴旗—榆林—神木—大柳塔一线以东至晋西北黄河沿岸的范围是侵蚀最为严重的地区，也是粗泥沙集中来源区的宏观待选范围。

In the extended experiment we modulate the sand grain diameter and air humidity to contrast with the natural result, discuss the effect of diameter and humidity on sand incipience, propose some ideas and methods to control sand transportation and formulation of wind-blow-sand flow.

本文还拓展了实验条件，通过调整沙粒粒径配比和空气湿度，完成了对比性实验，并进一步探讨了粒径和湿度对沙粒起动的影响，提出了在沙漠工程中控制风沙流形成和沙粒输运的思路和方法。

Our research analyzes comprehensively the sand data, such as thickness distribution, velocity distribution, frequency distribution of sand incipience velocity, expatiates the behaviors of these two sand incipiences in wind-blown-sand flow, then our research amends some deficiency of relative researches.

本文全面分析了沙粒浓度分布、速度分布和沙面上起动沙粒速度参数的频率分布等，阐述了两种沙粒起动方式在风沙流中的不同表现，并对相关研究资料中的不足进行修正。

This showed that capacity of water-holding in biological soil crusts were obvious improve,and effected precipitation permeate or water second distribute process.The study results of"fertile islands"formation mechanism in biological crusts showed that biological crusts layer cover could increased nutrients content for below sand soil through precipitation permeate washing,and it promoted plants assimilate more nutriment.The matter import ways of biological soil crusts fertility island had many ways,including the effection of living macrobiotics metabolism in crusts levels,wind-sand flow of near surface,dust deposition and plants decomposition course,etc.Source of particle matter in biological soil crusts was wind-sand flow of near surface,and not dust deposition.Biological crusts layer cover had preserved effection for nature water content in 0-5cm soil layer,compared with the sand of no biological crusts layer,effecting precipitation permeate,and could not obvious restrained from the water evaporate process indoor experiment.

生物结皮层肥岛形成机制的研究结果表明：生物结皮层覆盖能够通过降水淋溶作用而增加下层土壤养分的含量，进而促进植物对养分的吸收；生物结皮层养分输入有结皮生物代谢、降尘、风沙流和植物分解矿化作用等多(来源：A73e3B3eC论文网www.abclunwen.com)种途径，但生物结皮层的颗粒物质来源主要是近地表风沙流，而不是大气降尘；生物结皮层覆盖对0-5cm土层自然含水量有一定的保护作用，并影响降水向深层渗透，不能有效的阻止表层水分的蒸发进程；研究表明采取人工促进技术能够在流动沙丘上形成生物结皮层，实现流动沙地的快速治理。

The lift-off angle of saltating sand grain follows LogNorm4 function distribution; lift-off horizontal velocity, vertical velocity and resultant velocity of saltating sand grain and falling angle and vertical velocity of saltating sand grain follow Gamma function distribution; falling horizontal velocity and resultant velocity of saltating sand grain follow Pearson IV function distribution.

跃移沙粒起跳、降落速度分布函数利用风洞实验获得的沙粒跃移运动的片断轨迹，反推出沙粒起跳角度服从LogNorm4函数分布，跃移沙粒起跳水平、垂直及合成速度均服从Gamma函数分布。

The results show that, during the period of collision between the sand grain and the sand bed, the lost kinetic energy is more than half of the total energy. Moreover, because the percentage of collision angles with more than 0° is up to 70％, the vertical speed of sand increases even if the kinetic energy decreases, which ensures that the sand particles can receive more energy from the air to keep on the saltation movement.

实验结果表明，沙粒与沙床碰撞过程中损失的动能超过总能量的一半，且由于碰撞平面角大于0°的比例达到70％，即使沙粒在碰撞过程中能量有所损失，沙粒与沙床碰撞后垂直分速度增加的现象仍比较普遍，使得沙粒在与气流相互作用的过程中获取更多的能量，从而为沙粒的持续跃移提供了保证。

Effects of dry temperature and dry time on properties of heat cured sand and the relationship with binder composition are as follows:sands bonded by binders that are not modified have high strength when dry temperature is high and dry time is long,but their anti-wettability power is poor . Sands bonded by binders that are modified by B but not modified by M can be dried quickly and sand strength is high but anti-wettability power is also poor. Sands bonded by binders that are modified by M but not modified by B can also be dried quickly to obtain maximum strength,then the strength becomes lower when they are dried continually for more time. and sand strength is high but anti-wettability power is also poor. Sands bonded by binders that are modified by M as well as by B at the same time can be dried quickly to obtain maximum strength at low temperature and short time. But the anti-wettability of sand mold is best when they are dried at high temperature and long time.

烘干温度和烘干时间对热硬砂性能的影响及其与粘结剂改性的关系是：未经改性剂B和改性剂M改性的粘结剂砂，脱水速度较慢，烘干温度越高，时间越长，则硬化强度也越高，但未经改性的粘结剂热硬砂的抗吸湿性较差；经改性剂B而不经改性剂M改性的粘结剂热硬砂，烘干硬化速度较快，强度也高，但在高湿度下的抗吸湿性不好；经改性剂M改性而不经改性剂B改性的粘结剂热硬砂，烘干时强度先随烘干时间升高至最大值后，继续烘干时强度又出现下降；经改性剂B和经改性剂M共同改性的粘结剂热硬砂能在短时间和较低的烘干温度下就可烘干到最高强度，即烘干脱水的速度较快，但试样的抗吸湿性差，若在更高温度和更长时间下烘干，试样的抗吸湿性得到改善，综合考虑烘干强度和抗吸湿性要求，对于φ30×30mm试样，理想的烘干温度是200℃，烘干时间20分钟。

Hill sand can be used in producing high performance concrete of hill sand based on the research of high strength concrete of hill sand, hydro-concrete of hill sand and the usage of fly ash.

本研究课题是在已成功研制并实际应用的C60高强山砂混凝土的基础上，结合对微细活性掺合料性质的理论认识，充分利用贵州当地的混凝土材料，并掺入微细活性掺合料，研制一种新型的高性能混凝土，即山砂高性能混凝土。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。