The generation and redistribution of overland flow on a massive oxic soil in a eucalypt woodland within the semi-arid tropics of North Australia

There is a dearth of knowledge on the runoff processes of eucalypt woodland communities in the semi-arid tropics of Australia. The work was undertaken on a 100 m transect of a 0·8 degree hillslope typical of the ‘smooth plainlands’ of central-north Queensland. This paper introduces a new experimental design for measuring overland flow in such areas by way of a cascade system of unbounded runoff plots which allow the inputs and outputs between troughs to be calculated. Most storms generate overland flow. Time to overland flow ranges between 1 and 18 min where rain intensities are above 10mm hr⁻¹ and when the average detention storage of 3·6 mm is exceeded. The bare soil surfaces within the scattered grass understory control the runoff generation process through the temporal variability of field saturated hydraulic conductivity. The study demonstrated that overland flow is mainly redistributed over the freely-draining oxic soil. Some areas export more overland flow than they gain from upslope (runoff), others gain more overland flow than they export (runon). Over the study period only 2 per cent of total rain is transferred out of this 100 m transect as overland flow due to the short duration of storms, the relatively high soil permeability, and the low slope angle. The remainder adds to the large soil water store or deep drainage. The variability of runoff–runon over these ‘smooth plainlands’ highlights how results from bounded plots would be misleading in such areas.     

Three-dimensional simulations of a starburst wind

In order to better understand the formation of a starburst-driven wind, we have performed a series of three-dimensional hydrodynamical simulations in an inhomogeneous interstellar medium. We present the results of these simulations, which provide new insights into the formation of the optical filaments and the origin of the soft X-ray emission.     

Seismic amplifications from offshore to shore

The objective of this study is to determine numerical estimations of seismic amplifications of waves traveling from offshore to shore considering the effect of sea floor configurations. According to the Boundary Element Method, boundary elements were used to irradiate waves and density force can be determined for each element. From this hypothesis, Huygens’ Principle is implemented since diffracted waves are constructed at the boundary from which they are radiated and this is equivalent to Somigliana's theorem. Application of boundary conditions leads to determine a system of integral equations of Fredholm type of second kind, which is solved by the Gaussian method. Various numerical models were analyzed, a first one was used to validate the proposed formulation and some other models were used to show various ideal sea floor configurations to estimate seismic amplifications. Once the formulation was validated, basic slope configurations were studied for estimating spectra of seismic amplifications for various sea floor materials. In general terms, compressional waves (P-waves) can produce seismic amplifications of the incident wave in the order of 2–5. On the other hand, distortional waves (S-waves) can produce amplifications up to 5.5 times the incident wave. A relevant finding is that the highest seismic amplifications due to an offshore earthquake are always located near the shore-line and not offshore despite the seafloor configuration.     

Multi-resolution adaptive modeling of groundwater flow and transport problems

Many groundwater flow and transport problems, especially those with sharp fronts, narrow transition zones, layers and fingers, require extensive computational resources. In this paper, we present a novel multi-resolution adaptive Fup approach to solve the above mentioned problems. Our numerical procedure is the Adaptive Fup Collocation Method (AFCM), based on Fup basis functions and designed through a method of lines (MOL). Fup basis functions are localized and infinitely differentiable functions with compact support and are related to more standard choices such as splines or wavelets. This method enables the adaptive multi-resolution approach to solve problems with different spatial and temporal scales with a desired level of accuracy using the entire family of Fup basis functions. In addition, the utilized collocation algorithm enables the mesh free approach with consistent velocity approximation and flux continuity due to properties of the Fup basis functions. The introduced numerical procedure was tested and verified by a few characteristic groundwater flow and transport problems, the Buckley–Leverett multiphase flow problem, the 1-D vertical density driven problem and the standard 2-D seawater intrusion benchmark–Henry problem. The results demonstrate that the method is robust and efficient particularly when describing sharp fronts and narrow transition zones changing in space and time.     

可控源音频大地电磁法深部找矿实验效果

为了考查电磁法在探测深部金属矿及地质构造方面的实际效果,用可控源音频大地电磁法分别在埋深为500 m和1 100 m的两个已知隐伏铁、铜矿体上进行了实验工作。实验结果表明地电异常显示了矿体、断层以及岩层接触带的分布。在矿体埋藏深度小于500 m、矿层较厚时,地电异常十分明显;若矿体埋藏深度大于1 000 m,地电异常主要反应了控矿、容矿构造。     

悬链线法在水平定向钻轨迹设计中的应用探究

铝孔轨迹设计是非开挖水平定向钻施工中一项重要内容。其最优化设计在国内已较成熟,但多数优化设计未从力学方面进行优化设计。针对这一情况,引入悬链线法来优化水平定向钻轨迹设计。通过悬链线法的计算可知,优化后的轨迹不仅有利于降低钻杆回转阻力和扭矩消耗,提高机械钻速,增长管道使用年限,同时与传统设计方法相比较,其计算出的轨迹长度也比传统圆弧轨迹长度略短,表明了悬链线法在水平定向钻轨迹设计上具有一定的优势。     

生态干扰度:一种评价植被天然性程度的方法

地球上现存的植物或森林群落都是植被与其环境长期适应及人类长期干扰影响的结果 ,因此 ,现实的植被反映着历史上人类对它们不同程度的影响。‘生态干扰’的概念常常被用来描述历史上人类对植被或森林影响的大小 ,即‘生态干扰度’;或用来表示现实植被离开它的‘天然植被’的距离 ,即现实植被的‘天然性程度’。如此的‘天然植被’可以是 :( 1 )历史上从未受过人类任何干扰的‘原始植被’;( 2 )基于当前立地的‘潜在的自然植被’。然而 ,成百上千年以来人类对自然的利用干扰 ,致使真正的‘原始植被’现在几乎无处可寻。因此 ,‘潜在的自然植被’被用来作为生态干扰度估计或植被天然性程度评价的参照系。作为一种很实用的生态分析手段 ,生态干扰度的方法已被广泛地应用在农、林、水、景观、城市及自然保护等诸多领域的生态评价上。为此 ,本文论述了生态干扰度的概念、原理、方法和应用实例。     

高精度锥体棱镜的“自差法”检测技术

本文提出一种采用“自差法”检测高精度锥体棱镜的新方法，阐述检测原理与装置，建立检测角度和面形误差的定量判据，并给出一个实例说明其应用。实践表明，“自差法”检测技术对于产品质量的控制，具有快速准确和简便实用等特点。     

基于WRF数值模拟的夏季强对流测定方法研究

在固定时间内使WRF数值模式的预报和观测间距实现最小化,是实时准确测定夏季强对流的重要依据,因此研究一种基于WRF数值模拟的夏季强对流测定方法.通过分析河南省2018年7月2日至7月23日闪电定位资料和降水资料,统计夏季强对流天气中降水强度与闪电频数关系,将二者进行线性拟合,根据拟合结果将夏季强对流天气中闪电频数反演至降水强度,并将反演后的降水强度通过四维变分同化资料方法,同化至WRF数值模拟中,获取最终WRF极小化代价函数,实现夏季强对流天气实时准确测定.通过该方法对河南省某机场进行WRF数值模拟研究发现,模拟结果的水平风速、垂直速度、位温与扰动气压变化明显,可准确测定该机场的夏季强对流天气,具有可靠性.     

水产养殖遥感监测及信息自动提取方法研究

以海南省文昌地区为例,在沿海地区尝试利用遥感监测的手段提取水产养殖地块和面积.采用面向对象的分类方法进行监测,取得了理想效果,同时也提出了提高分类精度的建议.