水文科学的基本问题及当代前沿   总被引：1，自引：4，他引：1       下载免费PDF全文

刘国纬 《水科学进展》1990,31(5):685-689

回顾了新中国70年来水文科学的发展历程。阐述了水文科学的基本问题及其当代前沿：水圈及其与地球其他圈层的界面过程；水文循环及人类活动对水文循环的扰动；水文学研究的特点及其方法论；水文知识的应用等。提出了划分水文科学分支学科的科学基础，建议将水文科学划分为普通水文学、水文气象学、陆地水文学、生态水文学和应用水文学5个分支学科。  相似文献   

地理学的哲学贫困   总被引：36，自引：2，他引：36  

白光润 《地理学报》1995,50(3):279-287

本文分析了康德主义、新康德主义和逻辑实证主义对地理学发展的影响，认为现代地理学发展必须克服认识论上“二元论”、方法论上“例外主义”的困扰，走切合地理学研究对象实际的科学发展道路。  相似文献   

自检校平差中过度参数化的克服     

李德仁 《武汉大学学报(信息科学版)》1986,(3)

带附加参数的自检校平差是当今解析空中三角测量中补偿系统误差的最有效方法。可惜的是,当采用一个十分庞大的附加参数组时,在某些几何条件下将导致很坏的法方程系状态,从而使测求的平差结果很差。本文研究和试验了几种克服过度参数化的方法。它们不是用统计分析方法来消除某些附加参数的,因为这会引起实际计算的困难。本试验研究表明: ——如果采用飞行方向交叉的双区域,用自由附加参数平差,附加参数的可测定性和系统的可靠性均是可接受的; ——如果附加参数作为带权观测值,而且按信噪比确定其权,在许多情况下过度参数化将是可避免的。——如果所有的未知数按极大验后估计原理或岭估计原理处理成带权观测值,並给予一个小权(例如P=0.005～0.001),则在所试验的任何情况下均可克服过度参数化。  相似文献   

我国深层地热资源的认识与勘探方法建议   总被引：2，自引：0，他引：2  

孙冰 《中国煤田地质》2006,(Z1)

我国丰富的深层地热资源储量为加快深层勘探提供了基础,尽管目前深层地热勘探许与开发还存在着很多难度,但深层地热分布规律认识和回灌技术的日见成熟使加快深层地热勘探步伐成为可能。根据上述认识,提出了加强地热地质基础理论研究与勘探开发技术研究的目的与方法,以及进行地热资源勘查的地质调查、地球物理勘探、地热钻井工程及井试等技术方法。  相似文献   

A laboratory study of high chromium alloy wear in phosphate grinding mill     

G.L. Chen  D. Tao  B.K. Parekh 《International Journal of Mineral Processing》2006

Grinding mills are commonly used in the Florida phosphate industry to reduce particle size. The corrosion of metallic grinding media and mill liner is a very serious problem, particularly under acidic conditions as encountered in the Florida phosphate fertilizer industry. A statistical Box–Behnken Design (BBD) of experiments was performed to evaluate the effects of individual operating variables and their interactions on the wear rate of high chromium alloy during phosphate grinding. The variables examined in this study included grinding time, solution pH, rotation speed, mill crop load, and solids percentage. The wear tests were conducted using a specially designed grinding mill whose electrochemical potential can be controlled. The most significant variables and optimum conditions were identified from statistical analysis of the experimental results using response surface methodology (RSM). It has been shown that solution pH had the most significant effect on the wear rate. The optimum process parameters for minimum wear rate were solution pH at 8.7, rotation speed at 61 rpm, solid percentage at 65% and crop load at 58%.  相似文献   

Researching European 'alternative' food networks: some methodological considerations     

Laura Venn  Moya Kneafsey  Lewis Holloway  Rosie Cox  Elizabeth Dowler  Helena Tuomainen 《Area》2006,38(3):248-258

Recent European literature on 'alternative' food networks (AFNs) draws heavily upon an apparently accessible and diverse body of non-conventional food networks in the agro-food sector and whilst researchers frequently refer to individual examples of farmers markets, box schemes, producer cooperatives and community-supported agriculture projects, less attention is given to the methodological processes that facilitate the identification and examination of these networks. From the preliminary stages of a research project focusing on examples of AFNs, ² this paper examines the process of operationalizing AFNs research and reviews the difficulties associated with identifying, comparing and characterizing AFNs.  相似文献   

TiO₂ nanoparticle trails in garnet: implications of inclusion pressure-induced microcracks and spontaneous metamorphic-reaction healing during exhumation     

S. L. HWANG  P. SHEN  T. F. YUI  H. T. CHU 《Journal of Metamorphic Geology》2007,25(4):451-460

A new mechanism of cleaving-healing of garnet in metamorphic rocks during exhumation is reported. Almandine garnet with submicron multiple-phase inclusions characteristic of the GRAIL reaction, garnet + rutile = kyanite + ilmenite + low-quartz, was found by analytical electron microscopy to have non-epitaxial rutile nanoparticles distributed along internal {110} microcrack trails at the acute corner of submicron multiple-phase inclusions defined by the intersecting (110) and (011) mould surfaces. Such garnet microcracks were formed during lithostatic decompression due to a relatively high compressibility of quartz in the inclusion pockets and stress concentration at the acute corner. Spontaneous healing with accompanied formation of non-epitaxial rutile nanoparticles was activated predominantly via the GRAIL reaction due to high surface tension at the tip of microcracks and, to a lesser extent, decreasing lithostatic pressure or increasing inclusion pressure upon exhumation. This new mechanism of microcracking and healing involves stress build up, fracture propagation, mineral reaction, transport of elements to the reaction site and lowering of reaction boundaries by capillarity effect, all under the influence of thermodynamic and kinetic factors at the submicron-scale. Thus, TiO₂ nanoparticle trails in garnet provide additional information on the P–T path and may shed light on exhumation rates/mechanisms and metamorphic reactions/processes. Careful scrutiny of host minerals on the submicron scale is required to tell whether there are other metamorphic-reaction facilitated healing processes being overlooked by inappropriate techniques or being obliterated by the predominant healing processes of fluid infiltration and resorption zoning.  相似文献   

Getting it wrong first time: building an interdisciplinary research relationship   总被引：1，自引：0，他引：1  

Phil Jones  Neil Macdonald 《Area》2007,39(4):490-498

This paper addresses recent debates on the need for greater collaboration across the physical and human geography divide. We discuss some of the problems of producing work that can be considered genuinely interdisciplinary. The paper reflects on a project examining the use of sustainable drainage systems in Glasgow and how we unwittingly produced a piece of social science research looking at a physical science topic. We suggest that more than simply the need for 'trust' between researchers, the actual practice of working together in the field – and, indeed, having the opportunity to make mistakes and learn from them – is essential. In working together, academics have a better opportunity to understand each other's intellectual and epistemological framework and develop projects where researchers can move beyond their disciplinary boundaries and weave their expertise into a coherent research output.  相似文献   

Advanced Micro-XRF Method to Separate Sedimentary Rhythms and Event Layers in Sediments: Its Application to Lacustrine Sediment from Lake Suigetsu,Japan     

Nagayoshi Katsuta  Masao Takano  Shin-ichi Kawakami  Shoji Togami  Hitoshi Fukusawa  Mineo Kumazawa  Yoshinori Yasuda 《Journal of Paleolimnology》2007,37(2):259-271

Event-related sedimentary layers, which are deposited occasionally due to volcanic eruptions, earthquakes or heavy rains, are often contained in the rhythmical sequences of lacustrine and marine sediments. We have developed an analytical method for separating the sedimentary rhythms and the event layers identified using the scanning X-ray analytical microscope (SXAM) and obtained sequential profiles of seven elements Al, Si, K, Ca, Ti, Mn, and Fe in the lacustrine sediment from Lake Suigetsu, Japan. Two types of event layers could be detected from the elemental composition of 33 layers of sediment: three known volcanic ash layers and 30 clay layers containing 12 turbidites. The recurrence interval of the latter, which may potentially be initiated and archived by locally important earthquakes, is estimated to be an average of 640 ± 160 years by using Sompi event analysis (SEA) based on an autoregressive (AR) model. After removing those portions that represented event layers from the elemental profiles, we obtained event-removed (ER) temporal profiles based on the tephrochronology of the three volcanic ash layers. The ER temporal profiles of manganese and iron, probably representing the siderite content, showed a millennial-scale variation in the Holocene that corresponded well with ice-rafting events in the North Atlantic.  相似文献   

三层套合方差分析在区域化探中的应用及计算机实现——以新疆某地1:50 000区域化探为例     

冯伟华  张秦华  鲜鹏辉 《物探化探计算技术》2007,29(1):44-47

在区域化探中必须应用三层套合方差分析对样品的采样误差和分析误差进行统计分析。这里结合实例分析了该方法的计算模型,给出了计算流程,并应用VB语言实现了该统计方法。通过应用证明,该程序算法合理、操作简单、大大提高了工作效率。并且,该程序可以应用到其它领域对样品质量的分析评估。  相似文献