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为更准确了解蒸散发量(ET)时空分布及其随土地利用变化的规律,以MOD16数据为基础,探讨不同土地利用类型及其相互间转化对北京市蒸散耗水的影响。结果表明,2005~2015年间,北京市约有2587.69km^2的面积发生了土地利用类型的转变,其中变化最多者为林地转变为耕地,达213.57km^2;北京市植被覆盖区域多年ET平均值为406.63mm,北京市ET空间分布呈西北山区高、东南平原低的特点,且不同植被类型的ET大小不同,其中林地最大,草地次之,耕地最小;在2005~2015年,北京市ET呈上升趋势,速率为8.64mm/a,总耗水量的增加速率为4881.09×104 m3。植被覆盖减少和气象因素变化的综合作用导致北京市的蒸散耗水呈逐年上升趋势。 相似文献
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为了更准确地评估三种基于蒸发互补相关原理的实际蒸散发计算模型(AA模型、GG模型、CRAE模型)对实际蒸散发的估算能力,首先根据北江流域1964~1987年间的逐日气象资料和同期径流量数据,采用HBV模型模拟得到逐日实际蒸散发量,再利用三种模型分别估算该流域的逐日实际蒸散发量,并对计算结果进行初步分析比较,而后以HBV模型计算结果为标准进行原始参数的率定,最后在不同的时间尺度上对三种模型的实际蒸散发计算结果进行对比评价。结果表明,三种模型利用原始参数进行模拟的计算结果误差较大;模型参数经率定后,各模型的模拟精度在年、月尺度上均得到提高:以HBV模型模拟得到的实际蒸散发量为标准,计算所得年极差的变化情况分别为AA模型由274mm减至-0.1mm;GG模型由-84.5mm减至0.3mm;CRAE模型由-91.1mm减至0.3mm;AA模型与GG模型的模拟结果相似,在冬季均呈现出模拟结果偏大的现象。通过分析年、月尺度上的结果可知,在北江流域,三种模型中AA模型对实际蒸散发量的估算能力最佳。 相似文献
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根据嘉陵江流域内12个气象站点1956~2012年的逐日气象资料,分别采用改进前后的平流干旱模型对嘉陵江三个子流域的实际蒸散发进行模拟,提出了一种基于气候变化和土地利用变化的实际蒸散发(Ea)贡献率计算方法。结果表明,与水量平衡法的估算结果相比,改进后模型对Ea的估算精度高于原始模型,且修正后模型参数α与土地利用类型具有相关性;三个子流域的年际实际蒸散发变化主要受下垫面因素变化的影响,是气候变化对其影响的2~5倍。此外,气候变化导致涪江流域的Ea在整个评估期内减少,另外两个子流域的Ea增加;下垫面变化导致涪江和嘉陵江子流域Ea减小,渠江Ea增加。 相似文献
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研究淮河流域的水文循环过程及水量空间分布对合理开发利用水资源具有重要意义,采用VIC模型对淮河中上游地区各种水量要素(降水、蒸散发、地表径流、地下径流、植被截留水量、土壤含水率、截留水蒸发、植物散发、裸地及水面蒸发、降雪日的积雪深、积雪覆盖面积比等)的空间分布进行模拟。结果表明,模型反映的水量分布与实际的流域下垫面物理机制相符。流域的沙壤土和壤土地区的蒸散发量较大,而地表径流量较小。在有大面积水体或水库的区域,蒸散发量、植被截留水量很小,而地下径流量、深层土壤含水率较大。降雪日中流域的西北部更容易形成较大的积雪深。 相似文献
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为定量分析P-M公式和双源蒸散发模型在淮河流域上游地区的适用性及计算精度,将双源蒸散发模型及P-M公式计算得到的蒸散发量与流域内息县水文站实测蒸发皿蒸发量的相关性进行对比分析,并定量分析不同蒸散发输入对水文模拟精度的影响。研究结果表明,双源蒸散发模型计算值与实测值的相关性及其水文模拟精度更高,更适于淮河流域上游地区蒸散发计算。研究成果可为淮河流域上游无资料地区的水文模拟和蒸散发计算提供参考。 相似文献
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基于洵河流域1961~1986年的逐日气象资料和同期径流量资料,采用基于互补相关原理的实际蒸散发模型(AA模型、GG模型、CRAE模型)分别估算该流域的逐日实际蒸散发量。根据水量平衡法的实际蒸散发计算结果对三种模型的原始参数进行调整,并在不同的时间尺度上对三种模型进行了比较,评估了三种实际蒸散发模型的估算能力。结果表明,采用三种模型的原始参数计算出的实际蒸散发量误差较大;调整原始参数后,各模型对年实际蒸散发量的计算精度大为提高,逐月的估算效果也有不同程度改善;参数调整后的AA模型与GG模型的模拟结果相近,优于CRAE模型的模拟效果;年、月尺度的模型模拟效果综合分析表明GG模型在洵河流域的估算效果相对最佳。 相似文献
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潜在蒸散发是一个综合性气候因子,是流域水文循环模拟的主要输出量。针对现存潜在蒸散发量估算方法的适用性分析不够全面的问题,基于海河流域45个国家气象台站1960~2010年日气象数据序列,以Penman-Monteith方法估算量和蒸发皿蒸发量为基准,从潜在蒸散发估算量与蒸发皿蒸发量的相关性、年均值空间变化特征、年内四季空间变化特征和年际变化趋势四个方面,探讨了六种基于能量的潜在蒸散发估算方法的适用性。结果表明,Penman-Monteith方法在整个流域具有较强的适用性;六种基于能量方法中,Doorenbos-Pruitt方法、Makkink方法、Hargreaves方法估算效果较好。 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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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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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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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
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《International Journal of Hydrogen Energy》2022,47(83):35515-35526
The main purpose of this work is to propose a new method to evaluate the concentration distribution of the hydrogen jet by using a He–Ne laser through the jet. This research attempts to apply the expression of concentration Gaussian distribution, the refraction formula of inhomogeneous refractive index medium, and the concentration inversion function to disclose the displacement of the center of the laser spot at different heights in the gas jet. The spot images of the laser beam passing through the gas jet at three vertical heights z = 10d, 20d, 30d, and different radial positions are obtained. The radial spatial asymmetry of the gas jet is also found in the experiment. Finally, the calculated concentration distribution curve and the fluent simulation curve, it is found that the two results are very similar. Our findings show that the error between the concentration distribution of this method and the simulated concentration distribution reaches 2.43%. 相似文献
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介绍了汽轮机零件的封存特点、防锈要求及防锈油性能对比试验的方法,通过对试验结果的对比分析,客观验证了各种防锈油的性能。试验表明,只有选择了合适的防锈油,才能保证汽轮机零件长期封存的质量。 相似文献