Scaling snowdrift development rate

For successful snowdrift modelling, measured drift shapes should be geometrically similar to full-scale shapes and develop at rates that scale in a known manner. Consensus exists on most modelling methods and the similitude requirements needed to meet these objectives. A notable exception is the manner to scale drift development rates. A rationale is presented for rate scaling based on an independent model and prototype mass transport measurements. This approach is validated by comparing the rate of drift development for a model Wyoming snow fence with corresponding field data. This method yields excellent agreement, whereas the alternatives differ substantially.     

西澳大利亚州矿产投资环境分析及政策介绍

根据近年来我国地质矿产行业纷纷向外走出去的实际需要,通过对西澳大利亚州矿产投资方面相关资料的大量收集、翻译和整理,系统总结和分析了西澳大利亚州目前的经济、贸易、资源领域和与中国的投资关系,以及西澳大利亚州的矿业投资环境和政策,详细介绍了西澳大利亚州投资项目的审批程序以及所涉及到的各个方面的法律法规和审批原则。这对于今后想在西澳投资的地质矿产资源领域的企事业单位来说,具有一定的参考价值,也是非常需要了解的基本知识。     

考虑储层孔隙结构的岩石导电机制研究

经典Archie公式解决了测井数据的定量计算问题,但是,Archie公式只能用于孔隙结构相对简单的储层.面对日益复杂的油气勘探对象,Archie公式的计算精度受到一定的限制.本次研究,应用球管模型方法,针对不同孔隙结构研究了岩石饱和盐水及饱和油气时的导电性质,得到了不同孔隙结构、具有不同流体饱和度时岩石导电性的数值模拟结果. 本次研究的数值模拟结果证明岩石孔隙结构是导致岩电实验数据发散现象的因素之一,对比孔隙结构不同而饱和度相同岩石的导电性质,证明复杂孔隙结构是形成低电阻油层的重要因素.     

Centrifuge modelling for evaluation of seismic behaviour of stone masonry structure

Many surviving ancient monuments are freestanding stone masonry structures, which appear to be vulnerable to horizontal dynamic loads such as earthquakes. However, such structures have stood for thousands of years despite numerous historic earthquakes. This study proposes a scaled-down dynamic centrifuge modelling test to study how these masonry structures resist seismic loading. The test is proposed for seismic risk assessments to evaluate risk of damage from a future seismic event. The seismic behaviour of a 3-storey, freestanding stone block structure has been modelled and tested within a centrifuge. Models were made at 3 different scales and dynamic tests were conducted using different centrifugal acceleration fields so that the behaviours could be transformed to an equivalent full-scale prototype and compared. Data from 2 earthquakes and a sweeping signal were used to simulate the effects of earthquake ground motion within the centrifuge. The acceleration and frequency responses at each storey height of the model were recorded in different centrifugal acceleration fields. Similar behaviours appeared when the results of the small-scale models were transformed to a full-size prototype scale. This confirms that the seismic behaviour of stone masonry structures can be predicted using scaled-down models.     

Fractal approaches in investigating the time dynamics of self-potential hourly variability

Fractal tools have been used to investigate the time dynamics of hourly self-potential data, recorded during the year 2001 by five geoelectrical stations located in one of the most seismic areas of southern Italy. Scaling behaviour has been revealed by means of different statistics: the Lomb Periodogram method, the Detrended Fluctuation Analysis, the Higuchi analysis and the mean distance spanned within the time L. The values of the scaling exponents estimated by means of these methods indicate that the temporal fluctuations of the geoelectrical signals are not typical of purely random stochastic processes (i.e. white noise), but evidence the presence of long-range correlations. Furthermore, it is found that these correlations are linear.     

Pressure–settlement characteristics of rectangular footings on reinforced sand

A method has been proposed to obtain the pressure–settlement characteristics of rectangular footings resting on reinforced sand based on constitutive laws of soils. The confining effect of the reinforcement provided in the soil at different layers has been incorporated in the analysis by considering the equivalent stresses generated due to friction at the soil– reinforcement interface. The prerequisite of the method is the value of ultimate bearing capacity, which can be obtained from the approaches already available in literature. The value of settlement may be read directly from pressure–settlement curves for the given pressure intensity. Therefore, the rectangular footing resting on reinforced sand can be proportioned satisfying shear failure and settlement criteria.     

美国国土资源管理的经验与启示

纵观美国的国土资源管理史,结合我国国情、省情,概述了美国国土资源管理经历的个阶段,简介了其管理现状和给予我们的有益启示,总结了值得我们学习和借鉴的经验教3训,探讨了加强和改善我省国土资源管理的对策与建议。     

Scaling the Vertical Structure of Sea Breezes Revisited

The sea-breeze scaling of Steynis extended by incorporating data fromtwo additional locations. This is done primarily to remove concerns that the original scaling laws contain featuresspecific to the Vancouver data upon which they were based. This new analysis also employs the integrated, ratherthan instantaneous, heat flux proposed by Tijm. The analysis results in well-defined scaling laws for allthree locations, and include explicit latitude dependence, which was not possible in the earlier study. The integratedheat flux reveals systematic diurnal behaviour that is shown to result in a separate scaling law for diurnalevolution of sea breezes at a single location.     

基于东北玉米区域动力模型的低温冷害预报应用研究

在田间试验资料基础上，采用改进的发育模型和分区作物参数，结合前人有关研究成果建立了东北玉米区域动力模型，并利用模型模拟了12站40年 (1961~2000年) 玉米生长发育过程。确定抽雄期延迟天数为低温冷害指标，分析了历史低温冷害年及减产情况。模拟了典型冷害年和40年气候平均的0.25°×0.25°网格点玉米生长发育过程, 探讨了与区域气候模式结合进行低温冷害预报的方法。主要结论有:①玉米发育模型能够较好地模拟玉米发育期和发育期对低温冷害的响应，以抽雄期延迟天数为冷害指标评估的历史冷害发生状况基本符合历史实况。②模型有一定的模拟玉米生长量对低温冷害响应的能力，但还需要更多的试验数据校正品种参数，完善模型。③利用GIS技术，结合区域化的作物参数运行区域作物模型，是作物模型区域化应用的一种解决方案。④东北玉米区域动力模型解释性好，根据确定的害指标，以区域气候模式输出结果驱动玉米模型可以模拟和预测低温冷害，是农业气象灾害预测预报的一个有益的尝试。     

Scaling organization in the dynamics of blocks-and-faults systems

Some elements of the model of scaling organization of fracture tectonics (SOFT) are incorporated into the model of block structure dynamics (BSD). The resulting new model permits to obtain a power law relationship between earthquake energy and fault area with an exponent 3/2, as for observed seismicity. This is an important advantage of the new model in comparison with the BSD model, in which this dependence is generally linear.