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为了解水土保持治理对泥沙过程的影响,在分离了气候变化对水沙过程变化的影响后,结合变动范围法研究了黄河中游多沙粗沙区由于水土保持治理等人类活动引起的水文、泥沙变化的时空演变规律。结果表明,1953~2000年由水土保持工程导致较显著的黄河中游水文变化参数为反转数、10月月平均流量、90 d最小流量等12个IHA因子;较显著的泥沙变化参数为10月、4月月平均输沙量、年最大3 d输沙量等8个因子;黄河中游多沙粗沙区中多数流域的水文与泥沙变化程度具有相似的空间分布规律;工程措施对水沙过程变化的影响较直接,而非工程措施中植树造林对黄河中游水沙变化影响较大。 相似文献
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宁夏南部贫困地区生态环境建设与经济发展关系研究 总被引:1,自引:0,他引:1
水土保持生态环境建设是一项社会公益性事业,其治理周期长、见效慢。在水土保持综合治理、监督执法和监测预报工作中,要坚持小流域综合治理;山、水、田、林、草、路集中连片规模治理;沟沟岔岔建坝系,拦泥蓄水;坡改梯、封山禁牧、舍饲养殖,人与自然和谐相处,改善贫困山区生态环境。 相似文献
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黄土丘陵沟壑区沟道土地整治工程对流域产汇流的影响 总被引:4,自引:0,他引:4
针对黄土高原丘陵沟壑区沟道整治工程造成的下垫面的剧烈变化,通过野外调查、室内试验模拟的方法,研究了流域沟道不同整治比例(0%、20%、30%、40%、50%)、不同降雨强度(40、60、80、100、120mm/h)情况下,沟道地表径流流速变化、流域控制工程坝前蓄水变化及对沟道洪水标准的影响。结果表明,随着沟道整治比例的增大,相对于沟道无整治工程时地表径流平均流速分别减小6.21%、10.95%、19.85%、21.78%,流域控制工程坝前平均蓄水分别减小3.94%、15.55%、17.23%、23.90%,径流系数由无整治工程时的0.80减小至0.61。随着降雨强度的增大,平均流速由0.102m/s增大至0.160m/s,流域控制工程坝前平均蓄水与40mm/h时相比分别增加5.90%、24.17%、30.80%、38.82%,径流系数由0.59扩大至0.81。由此可见,流域沟道不同整治比例和不同降雨强度对流域控制工程的径流蓄积、径流系数及洪水设计均具有较大影响,实际工程设计中应考虑其影响,不可忽略。 相似文献
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坝下游河床冲刷粗化的一个计算方法 总被引:2,自引:0,他引:2
本文在非均匀沙起动及输移规律研究的基础上,对坝下游河床冲刷粗化进行了研究,提出了河床冲刷深度及粗化稳定级配的计算公式,验证结果令人满意. 相似文献
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以沙牌拱坝为例,将坝体及两岸潜在滑动块体在内的近域地基作为一个体系,考虑坝—基—库水动力相互
作用、坝体混凝土破坏、无限地基辐射阻尼、坝体横缝与坝肩可能滑动岩块结构面的动态接触非线性效应及坝基
裂隙岩体的非线性等因素的影响,研究了沙牌拱坝在不同概率水平地震作用下的地震响应与破坏形态,提出以坝
体控制性位移时程曲线的突变并无限增长、坝基交界面出现贯通性破坏区及有限元计算发散作为拱坝整体失稳的
判据,评价了高拱坝的整体抗震安全性,获得了一些有益的结论,可供借鉴。 相似文献
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砂土区淤地坝破坏的主要形式是渗流,在淤地坝的反滤体中运用土壤固化剂能够防止渗透破坏的发生。为探寻一种最优配比的无机固化剂,以陕西省榆林市靖边县沙旋沟淤地坝筑坝土料为例,通过原土料和添加不同配比固化剂土料的渗透破坏试验,对比分析不同配比固化剂的完全破坏临界水力坡降来寻找最优配比的固化剂,并将选出的最优固化剂应用于模型坝的试验中来检验固化剂的实际效果。结果表明,所有土料渗流流速在渗透破坏前均随水力坡降的增大而增大;添加固化剂降低了土样的渗流流速,增加了土样的抗渗能力和稳定性,其中添加5%的无机复合固化剂土样的效果最好;在模型试验中,添加无机复合固化剂的土料对于"坝后流泥"现象具有一定的修复效果。 相似文献
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以300m级双江口心墙堆石坝为研究对象,采用有限元动力时程稳定与变形分析方法,研究了高土石坝顶部1/5坝高范围内采用土工格栅加筋措施对坝坡动力稳定与变形的影响。结果表明,采用土工格栅加筋措施后,增强了高土石坝坝顶区堆石体的整体稳定性,坝坡最危险滑弧深度增加,有效提高了坝坡安全系数;土工格栅加筋方案明显抑制了坝坡滑动位移,最小安全系数对应滑弧的累积滑动量减小。随着输入地震动峰值增加,土工格栅加筋方案对坝坡动力稳定贡献越大。 相似文献
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《International Journal of Hydrogen Energy》2022,47(63):26789-26797
The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO2 and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized. 相似文献
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基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁(MgO),研究了该型MgO膨胀剂(MEA)细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析(TG DSC)分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。 相似文献
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Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined. 相似文献
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使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。 相似文献
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M.R. Salimpour M. SharifhasanE. Shirani 《International Communications in Heat and Mass Transfer》2011,38(1):93-99
This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed. 相似文献
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General expressions for the heat of vaporization of mixtures at constant pressure; at constant temperature; and at constant pressure, temperature, and composition are proposed. The last one is related to the liquid-vapor interface where steady vaporization or condensation is taking place. Numerical examples by the proposed expressions are shown for binary mixtures of HCFC22(R22) and (HCFC123(R123) © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(1): 12–24, 1996 相似文献
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本文对漫灰均温物体在常物性条件下对外辐射传热的Yong值计算建立了数学模型。通过与物体内能Yong公式的数值计算比较,得出了辐射能量的Yong值不大于内能Yong值的结论。从初步的热射Yong值计算公式发现。Yong与物体表面辐射率有关。 相似文献