灌溉水利用效率随尺度变化规律分布式模拟   总被引：5，自引：0，他引：5       下载免费PDF全文

谢先红  崔远来 《水科学进展》2010,21(5):681-689

为评价农田灌溉水利用状况并揭示灌溉水利用效率的尺度变化规律,应用改进的分布式水文模型(SWAT)模拟了漳河灌区三干渠灌域的水循环过程和作物产量。以子流域嵌套方式将研究区划分为9个尺度来计算灌溉水利用效率指标,并分析其随尺度变化的特征及原因。结果表明,灌溉水分生产率受降雨、气候条件的时空分布特征影响较大,而且随尺度增大明显,其尺度关系可以近似应用幂函数描述,函数的形式和参数与分形思想接近。排水率在中等尺度上的数值最大,但随尺度变化不显著。因此,在一定精度条件下,灌溉水分生产率的尺度转换模式可以尝试应用幂函数形式。漳河灌区在中等尺度上的节水潜力最大。  相似文献   

可变水量控制在地源热泵系统中的应用     

吴德明  叶宏标 《中国勘察设计》2010,(10):27-32

把多个控制回路应用在地源热泵系统中,实现最佳的系统的、动态的能效比,从而达到整个系统的最大节能。  相似文献   

壳体大小对浮游有孔虫生物地球化学记录的影响   总被引：1，自引：0，他引：1  

徐建 《矿物岩石地球化学通报》2010,29(2):109-118

在浮游有孔虫壳体稳定同位素及Mg/Ca和Sr/Ca值的相关研究中,人们常因各种原因而选择不同粒径的壳体进行分析测试,而很少注意壳体大小可能导致研究结果的分歧。针对这一问题,本文分析了位于低纬度海区钻孔中不同粒径的Glo-bigerinoides ruber(白色,sensu stricto)和Pulleniatinaobliquiloculata壳体,结果表明G.ruber壳体的δ13C值受壳体大小的影响最为强烈,表现为正相关关系,不同粒径壳体的δ13C绝对平均差值可达0.48‰±0.12‰和0.25‰±0.09‰;P.obliquiloc-ulata400μm与315~400μm和250~315μm壳体Mg/Ca值的差异相当于1.8℃的海水温度;相对而言,G.ruberδ18O和Mg/Ca值以及P.obliquiloculataδ13C受壳体大小的影响较小,但它们的Sr/Ca值与壳体大小的关系不显著。本文推测,壳体大小相同时厚重的壳体可能成壳速度较快,相对优先吸收轻的同位素,且壳体Mg/Ca值可能更接近周围海水的水平。据此,本文认为较大个体P.obliquiloculata的壳体分泌可能与周围海水达到了平衡分馏。  相似文献   

粘土中圆形隧道上限解的研究     

尹小军 《岩土工程技术》2010,24(1):20-23

根据极限分析上限理论,基于Davis等人提出的隧道垮落模型,提出了剪切区参数α等于1时的新的隧道垮落模型。由不可压缩性条件和速度连续性条件求出了剪切区速度和间断线表达式,计算了该模型间断线上能量耗损、剪切区能量耗损和总外力所做的功。利用功能原理,求出了稳定率的表达式,并计算了相应的稳定率。从求解结果来看,所得上限解小于Davis等人的结果,因而该上限解将更接近真实解。从与实验结果比较来看,该上限解位于实验值附近,能与实验结果比较好地吻合,从而说明该模型更加接近真实隧道垮落情形。该上限解可为隧道支护提供理论依据。  相似文献   

Crustal Composition of China Continent Constrained from Heat Flow Data and Helium Isotope Ratio of Underground Fluid   总被引：3，自引：1，他引：2  

WANG Yang  and SUN Zhiming 《《地质学报》英文版》2010,84(1):178-184

Based on conservation of energy principle and heat flow data in China continent, the upper limit of 1.3 μW/m3 heat production is obtained for continental crust in China. Furthermore, using the data of heat flow and helium isotope ratio of underground fluid, the heat productions of different tectonic units in China continent are estimated in range of 0.58–1.12 μW/m3 with a median of 0.85 μW/m3. Accordingly, the contents of U, Th and K2O in China crust are in ranges of 0.83–1.76 μg/g, 3.16–6.69 μg/g, and 1.0%–2.12%, respectively. These results indicate that the abundance of radioactive elements in the crust of China continent is much higher than that of Archean crust; and this fact implies China’s continental crust is much evolved in chemical composition. Meanwhile, significant lateral variation of crustal composition is also exhibited among different tectonic units in China continent. The crust of eastern China is much enriched in incompatible elements such as U, Th and K than that of western China; and the crust of orogenic belts is more enriched than that of platform regions. It can also be inferred that the crusts of eastern China and orogenic belts are much felsic than those of western China and platform regions, respectively, derived from the positive correlation between the heat production and SiO2 content of bulk crust. This deduction is consistent with the results derived from the crustal seismic velocity data in China. According to the facts of the lower seismic velocity of China than the average value of global crust, and the higher heat production of China continent compared with global crust composition models published by previous studies, it is deduced that the average composition models of global continent crust by Rudnick and Fountain (1995), Rudnick and Gao (2003), Weaver and Tarney (1984), Shaw et al. (1986), and Wedepohl (1995) overestimate the abundance of incompatible elements such as U, Th and K of continental crust.  相似文献   

广西铜聋山铜铅锌矿床遥感地质信息研究          下载免费PDF全文

成永生 《地质找矿论丛》2010,25(4):351-355

针对铜聋山矿区的地质特征及成矿地质条件,应用卫星遥感技术方法对该区进行了综合研究。利用美国陆地卫星Landsat-5的TM多波段数据对研究区的构造信息进行了综合解译,结合主成分分析与波段比值法对矿化蚀变信息进行了提取。结果表明,该区的主要成矿构造为NE向断裂,线环构造的交汇部位是成矿的最佳环境;遥感矿化蚀变信息得到了有效的增强,与已知矿点具有很好的一致性,能够反映有利的找矿目标。  相似文献   

北京粉尘沉降物的物理化学特征及其物源初探   总被引：2，自引：0，他引：2  

刘永生  杨冰  李瑞敏  王轶  曹峰  徐慧珍  李爱国 《地质通报》2010,29(8):1220-1227

对北京上空不同高度不同时间段采集的粉尘样品的物理化学特征进行了研究。认为不同的风动力作用导致北京上空粉尘不同来源的物质高度混合,且高度越高远源物质越多,高度越低近源物质越多。由于物质来源不同,粉尘的物理化学特征呈现出不同的特点。通过研究发现,Si/Al比值能近似地反映粉尘在空中的分布特征,可以作为粉尘扬起高度的间接指标。  相似文献   

基于Shepard和OI方法对雨量计逐时资料的分析   总被引：1，自引：0，他引：1       下载免费PDF全文

李春晖  梁建茵 《应用气象学报》2010,21(4):416-422

引入地形影响效应的日降水量气候分析场,分别运用Shepard和最优插值(OI)两种插值方法对广东和广西2007年5月20日—8月30日汛期小时雨量计降水量进行插值,得到0.125°×0.125°分辨率的规范化网格资料。结果表明:无论是直接插值还是用降水比率(地形影响效应的日降水量气候分析场)插值,两种方法均能很好地体现广东和广西雨量计站点观测降水的季内变化和日变化特征。虽然用直接插值方法比用降水比率插值方法得到的降水空间分布更为平滑,但估值精度没有用降水比率插值方法高。通过交叉检验进一步表明,总体上OI方法优于Shepard方法,而考虑地形影响效应的降水比率OI方法为最优,能有效提高相关性,并减少均方根误差和系统误差。  相似文献   

Stress integration approach to evaluate damping ratio in torsional tests     

Yoon‐Shin Bae  Inthuorn Sasanakul 《国际地质力学数值与分析法杂志》2011,35(17):1842-1853

The complexity of determining strain associated with shear modulus and damping ratio in torsional tests has been resolved by means of several approaches. The stress integration approach is adequate when generating the plots of equivalent radius ratio versus strain more effectively over any range of strains in resonant column and torsional shear (RC/TS) tests. The stress integration approach was applied for hyperbolic, modified hyperbolic, and Ramberg–Osgood models in evaluating damping ratio. This study showed that using a single value of equivalent radius ratio in evaluating damping ratio is not appropriate. The combined hysteretic‐nonviscous damping model was developed and employed to consider the increased damping behavior at small strains using the stress integration approach. The results suggest that adding viscous behavior has no significant effect strain calculations in RC/TS testing. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Dynamic topography of the East European craton: Shedding light upon lithospheric structure, composition and mantle dynamics     

Irina M. Artemieva   《Global and Planetary Change》2007,58(1-4):411

Most of the East European Craton lacks surface relief; however, the amplitude of topography at the top of the basement exceeds 20 km, the amplitude of topography undulations at the crustal base reaches almost 30 km with an amazing amplitude of ca. 50 km in variation in the thickness of the crystalline crust, and the amplitude of topography variations at the lithosphere–asthenosphere boundary exceeds 200 km. This paper examines the relative contributions of the crust, the subcrustal lithosphere, and the dynamic support of the sublithospheric mantle to maintain surface topography, using regional seismic data on the structure of the crystalline crust and the sedimentary cover, and thermal and large-scale P- and S-wave seismic tomography data on the structure of the lithospheric mantle. For the Precambrian lithosphere, an analysis of Vp/Vs ratio at 100, 150, 200, and 250 km depths does not show any age-dependence, suggesting that while Vp/Vs ratio can be effectively used to outline the cratonic margins, it is not sensitive to compositional variations within the cratonic lithosphere.Statistical analysis of age-dependence of velocity, density, and thermal structure of the continental crust and subcrustal lithosphere in the study area (0–62E, 45–72N) allows to link lithospheric structure with the tectonic evolution of the region since the Archean. Crustal thickness decreases systematically with age from 42–44 km in regions older than 1.6 Ga to 37–40 km in the Paleozoic–Mesoproterozoic structures, and to ca. 31 km in the Meso-Cenozoic regions. However, the isostatic contribution of the crust to the surface topography of the East European Craton is almost independent of age (ca. 4.5 km) due to an interplay of age-dependent crustal and sedimentary thicknesses and lithospheric temperatures.On the contrary, the contribution of the subcrustal lithosphere to the surface topography strongly depends on the age, being slightly positive (+ 0.3 + 0.7 km) for the regions older than 1.6 Ga and negative (− 0.5–1 km) for younger structures. This leads to age-dependent variations in the residual topography, i.e. the topography which cannot be explained by the assumed thermal and density structure of the lithosphere, and which can (at least partly) originate from the dynamic component caused by the mantle flow. Positive dynamic topography at the cratonic margins, which exceeds 2 km in the Norwegian Caledonides and in the Urals, clearly links their on-going uplift with deep mantle processes. Negative residual topography beneath the Archean-Paleoproterozoic cratons (− 1–2 km) indicates either a smaller density deficit (ca. 0.9%) in their subcrustal lithosphere than predicted by global petrologic data on mantle-derived xenoliths or the presence of a strong convective downwelling in the mantle. Such mantle downflows can effectively divert heat from the lithospheric base, leading to a long-term survival of the Archean-Paleoproterozoic lithosphere.  相似文献