激发极化法的“饱和效应”问题

西格尔（H.O.Seigel）从理论计算得到导电颗粒含量为25％的极化球体有最大异常,因此认为:激发极化法只宜于寻找中等浸染程度的矿体,对于含量很高的矿体或良导致密型矿体,激发极化法是不行的。据称这种“饱和效应”的理论得到野外结果的证实。 本文根据我国激发极化法在良导致密型矿体上大都能获得明显视极化率异常的事实,说明西格尔的“饱和效应”理论与事实不符。本文认为良导致密型极化体不存在“饱和效应”问题,激发极化法对它们的勘探也是有效的。可能由于西格尔把低含量理论公式,不计条件地推导到高含量、甚至良导矿体,因此他的结论是错误的。本文最后讨论了电阻率因素对浸染型球体视极化率强度的影响。     

激发极化法的“饱和效应”问题

西格尔（H.O.Seigel）从理论计算得到导电颗粒含量为25％的极化球体有最大异常,因此认为:激发极化法只宜于寻找中等浸染程度的矿体,对于含量很高的矿体或良导致密型矿体,激发极化法是不行的。据称这种“饱和效应”的理论得到野外结果的证实。 本文根据我国激发极化法在良导致密型矿体上大都能获得明显视极化率异常的事实,说明西格尔的“饱和效应”理论与事实不符。本文认为良导致密型极化体不存在“饱和效应”问题,激发极化法对它们的勘探也是有效的。可能由于西格尔把低含量理论公式,不计条件地推导到高含量、甚至良导矿体,因此他的结论是错误的。本文最后讨论了电阻率因素对浸染型球体视极化率强度的影响。     

轴对称二维任意非均匀介质中偏轴点源激励的位场数值解

对具有任意多平面分层，且每一平面分层中又具有任意多径向柱面分层的复杂非均匀介质中偏轴点源激励的位场分布进行了高效数值分析．对于这种三维非均匀位场分布，应用数值本征模展开描述其径向的基模和高阶模，用集合反射矩阵和集合透射矩阵匹配各平面界面的边界条件，各平面分层中的位场则用递推算法获得．偏轴点源位场的求解，为电法测井中高分辨薄五层探测提供了理论分析基础．     

Optimum absorber parameters for simple systems

In the classical problem a damped one degree-of-freedom absorber system is attached to a main system, which has one degree of freedom and is undamped. The optimum values of absorber stiffness and damping, which will minimize the resonant response of the main mass, are well known. In this paper the effect on these optimum conditions of light damping in the main system is studied. The authors show that optimum parameters for absorbers, which are attached to beams and plates, can be obtained simply and accurately from those for an equivalent one degree-of-freedom main system. This depends upon the concept of an effective mass for the elastic body and the representation of its response by the single relevant mode. It will be shown in a later paper that for more complex elastic bodies such as cylindrical shells, for which the natural frequencies are more closely spaced, these simple concepts do not predict accurately optimum absorber parameters.     

Field determination of air-sea gas exchange by continuous measurement of radon-222

Equipment has been developed for automatic measurement of the radon dissolved in sea water, with the aim of determining gas exchange rates at sea on the basis of the radon-222 deficiency in the mixed layer with respect to its parent nuclide radium-226. The equipment will be employed to obtain, over an extended period at fixed position, repeated measurements of the vertically integrated radon deficiency. The repetition period will be 2 hours, and sampling will be by a winch-operated submersible pumping system which will continuously scan the radon-deficient layer. The repeated measurements will allow to derive gas exchange rates even under transient meteorological conditions. As opposed to this, radon work carried out to date relied on isolated deficiency measurements and stationary conditions were commonly assumed (the deficiency relaxation time is about 5 days), which, under transient conditions, may lead to considerable errors. Equipment tests have been made at sea and the first integrated-deficiency measurements were obtained on the RSSChallenger in July 1977. Field programs are in preparation for JASIn (Joint Air-Sea Interaction, July–September 1978) and FGGE (First GARP Global Experiment, January–July 1979). The ultimate goal is a parameterization of the gas exchange rate in terms of external parameters, primarily wind speed.     

关于大地电流数据整理的总合法

大地电流法在石油普查地区探測高电阻基岩层的起伏情况,是一种有效而且經济的地球物理方法。但是目前在观察数据整理的問題上,尚存在着一些混乱現象。由于整理方法的众多,在同一地区采用不同的方法,往往不能对比。     

关于大地电流数据整理的总合法

大地电流法在石油普查地区探測高电阻基岩层的起伏情况,是一种有效而且經济的地球物理方法。但是目前在观察数据整理的問題上,尚存在着一些混乱現象。由于整理方法的众多,在同一地区采用不同的方法,往往不能对比。     

An approach to the intercalibration of benthic ecological status assessment in the North Atlantic ecoregion, according to the European Water Framework Directive

The European Water Framework Directive (WFD) establishes a framework for the protection and improvement of transitional and coastal waters; its final objective is to achieve at least 'good water status' for all waters, by 2015. The WFD requires Member States (MSs) to assess the Ecological Status (ES) of water bodies. This assessment will be based upon the status of the biological, hydromorphological and physico-chemical quality elements, by comparing data obtained from monitoring networks to reference (undisturbed) conditions, and then deriving an Ecological Quality Ratio (EQR). One of the biological quality elements to be considered is the benthic invertebrate component and some structural parameters (composition, diversity and disturbance-sensitive taxa) must be included in the ES assessment. Following these criteria, several approaches to benthic invertebrate assessment have been proposed by MSs. The WFD requires that these approaches are intercalibrated. This contribution describes the comparison of the different methodologies proposed by United Kingdom, Spain, Denmark and Norway. Results show a high consistency between the approaches, both with regard to determining the EQR and boundary settings for the ES.     

Mechanism and bounding of earthquake energy input to building structure on surface ground subjected to engineering bedrock motion

The mechanism of earthquake energy input to building structures is clarified by considering the surface ground amplification and soil–structure interaction. The earthquake input energies to superstructures, soil–foundation systems and total swaying–rocking system are obtained by taking the corresponding appropriate free bodies into account and defining the energy transfer functions. It has been made clear that, when the ground surface motion is white, the input energy to the swaying–rocking model is constant regardless of the soil property (input energy constant property). The upper bound of earthquake input energy to the swaying–rocking model is derived for the model including the surface ground amplification by taking full advantage of the above-mentioned input energy constant property and introducing the envelope function for the transfer function of the surface ground amplification. Extension of the theory to a general earthquake ground motion model at the engineering bedrock is also made by taking full advantage of the above-mentioned input energy constant property.     

Dynamics of three-block assemblies with unilateral deformable contacts. Part 1: contact modelling

As far as the dynamics of multibody systems is concerned, a brief review has been performed in order to frame the dynamic response of a trilith (the simplest scheme of a colonnade belonging to a temple) into a wide theoretical background. Under the assumption of rigid bodies, two different approaches can be found in the literature: rigid or deformable contacts formulation. In this paper, an effort is made at outlining the principle of rigid contact formulation and of deformable contact formulation. The latter approach can be assumed within the framework of the distinct element method; for this purpose a model of deformable contact has been proposed in order to simulate the real behaviour of stone joints. The sample application referred to the trilith will be presented in Part 2. Copyright © 1999 John Wiley & Sons, Ltd.     

Die EG‐Wasserrahmenrichtlinie: Ausweisung und Bewertung künstlicher und erheblich veränderter Gewässer

Designation and Assessment of Artificial and Heavily Modified Water Bodies under the EC Water Framework Directive The EC Water Framework Directive allows the Member States to designate artificial and heavily modified water bodies under specific conditions. For those water bodies the ecological assessment and the resulting programmes of measures will be based on the “maximum ecological potential” as reference conditions and not on the “high ecological status”, which has to be used for natural water bodies. Such designation is possible only, if the hydromorphology of the water bodies concerned has been substantially changed in character to maintain specified uses. The criteria for the designation are fulfilled, if restoration measures needed to meet the high ecological status would have significant adverse effects on the uses and if no other better environmental options would exist to maintain the specified uses. In late 1999 the EC‐Working Group on Heavily Modified Water Bodies (HMWB) has been established to develop criteria for the designation of artificial and heavily modified water bodies as well as for the determination of the maximum ecological potential. The working group has produced the guidance document “Identification and Designation of Artificial and Heavily Modified Water Bodies” in November 2002, which has been agreed by the European Water Directors on 21 November 2002 in Copenhagen. The guidance document is focusing on two time borders, the provisional identification of heavily modified water bodies until 2004 and the legally binding designation as artificial and heavily modified in the first river basin management plan in 2009 at the latest. The guidance document considered the main findings of 34 case studies for rivers, lakes, transitional and coastal waters carried out in 11 European countries. The results of the case studies as well as a summarizing synthesis were used as a fundamental basis to produce the guidance document. The practical examples given by the case studies were compiled as a toolbox which supplements the guidance for the purpose of its better application.     

MODELING SEDIMENT PROCESSES ON SMALL WATERSHEDS: A CONCEPTUAL FRAMEWORK Ⅱ. CONCENTRATED FLOW PROCESSES

L INTRODUCTIONThe purpose of this paper is to present a general modeling framework that can serveas a conceptual basis for developing sediment process models by concentrated flow systems on small watersheds. A survey of fundamental principles for developing sedimentprocess models is made with particular emphasis on the effects of space and time averaging on the governing equations. Starting from the most general one--dimensional,unsteady model of sediment processes, simpler model structur…     

Assessing the trophic state of water bodies by high-resolution remote spectrometry in visible band

Analysis is presented of many-year spectrometric data in the visible band of electromagnetic spectrum collected for the Don R., including the Tsimlyansk Reservoir in 2010–2013 with a period of ~15 days. An algorithm has been proposed for separating spectral brightness coefficient of the rising radiation from water into six categories. A nomenclature scale of the trophic status of water bodies has been constructed. The obtained scale coincides with the nomenclature scales constructed by chlorophyll a concentration for water bodies under different physiographic conditions. The unquestioning advantage of remote sensing methods for assessing water body (WB) trophic status is emphasized, i.e., the possibility to carry out real-time studies within minutes at high representativeness of the results with respect to the examined aquatic ecosystem.     

The challenge of placing in situ magnetotail observations into global context

The last 4 years have seen an explosion of studies of magnetotail structure and dynamics. Growth in our understanding of the coupling of the magnetotail to the inner magnetosphere and ionosphere and the response of the magnetotail to solar wind dynamics has been made possible because of the International Solar Terrestrial Physics (ISTP) program. In addition, the sophistication of global modeling techniques and algorithms have allowed direct comparison of in situ data with realistic global models to understand better not only the general structure of the magnetosphere but also its dynamics. This brief review will discuss in situ observations made during the ISTP era and attempt to place them into a global context. Magnetotail structure and its dynamics due to external and internal drivers will be the main focus.     

Stochastic response of suspension bridges to earthquake forces

The purpose of the paper is to study the applicability of stochastic methods for determining the response in the vertical plane of long-span bridges to earthquakes. The bridges are of the modern type, with flexible towers, box-decks and inclined hangers, Humber and Bosporus being used as the main examples, although some useful information is obtained by studying a small suspension footbridge. The input ground acceleration is that of the Pacoima Dam record of the 1971 San Fernando event, but use is also made of filtered white noise. Because the stochastic approach is essentially an attempt to abstract usable information which could otherwise be obtained from a lengthy time-history approach, the procedure adopted here is to compare the same parameters obtained in these two ways, as far as possible. In particular, the maximum values of displacements and bending moments are considered. The essential question to be answered is whether the short length of earthquake records, coupled with the large natural periods of vibration of long-span bridges, allows sufficient response information to be generated to make statistical parameters meaningful. The short-span (50 m) footbridge gives no cause for concern here, but the detailed comparison with time-history solutions shows that the stochastic approach for both Bosporus and Humber has to be cautiously assessed, particularly if some trailing zeros are not added to the earthquake record. However, general conclusions are not made, because only one earthquake record has been used.     

On the physical model of earthquake precursor fields and the mechanism of precursors’ time-space distribution — origin and evidences of the strong body earthquake-generating model

According to the requirement of the project “Establishment of the Physical Model of Earthquake Precursor Fields”, this paper elucidates the train of thinking for research on the project and some scientific problems which must be studied; the elucidation emphasizes that the core of this project is to study the conditions and processes of the generation of strong earthquakes. The paper first outlines the origin and development of the “strong-body earthquake-generating model” proposed by the author in the 1980’s; and then proves the reasonableness of the model from three aspects, namely: deep structures, mechanical analysis and rock fracture experiments. By studying the tomographic image for the northern part of North China, it can be seen that the sources of strong earthquakes are all distributed in high-velocity bodies, or in the contact zone between high-velocity and low-velocity bodies but nearer to the high-velocity body. It has been affirmed through studies of the mechanical models of hard and soft inclusions that the existence of a hard inclusion is an important condition for the high concentration of large amounts of strain energy. A lot of theoretical and experimental studies have been made to investigate the conditions for rock instability; the results have consistently indicated that rock instability, sudden fracture and stress drop would be possible only if the stiffness of the source body is greater than the environmental stiffness.     

大地电磁相位超象限现象的各向异性模型研究——以上下结构为例

大地电磁观测数据中的相位超象限现象可以由不同的电性结构产生.本文在已实现大地电磁三维任意各向异性有限差分正演的基础上,以具有上下结构关系的三维各向异性模型为例,分析各向异性体的规模以及参数变化对阻抗相位的影响.在下部各向异性体规模明显大于上部各向异性体或表现为层状特征的情况下,上部各向异性体在两个水平方向上的尺度差异较大,可以看作准二维体时容易发生相位超象限;当上部各向异性体在两个水平方向上尺度相近表现为规则三维体时,要产生相位超象限的现象则需要各向异性体具有更高的各向异性比.在同等条件下,增加各向异性体的各向异性比更容易发生相位超象限;而各向异性走向方位角的变化将直接影响到发生相位超象限的范围.对于准二维模型引起相位超象限的条件,沿用二维模型的近似解析分析方法,进一步构建了基于各向异性体的电导率、背景电导率以及各向异性走向角的相位超象限指标函数,从而更加直观地解释在二维或准二维条件下发生相位超象限现象的模型参数特征.

     

Depth and structural index from normalized local wavenumber of 2D magnetic anomalies

Recent improvements in the local wavenumber approach have made it possible to estimate both the depth and model type of buried bodies from magnetic data. However, these improvements require calculation of third‐order derivatives of the magnetic field, which greatly enhances noise. As a result, the improvements are restricted to data of high quality. We present an alternative method to estimate both the depth and model type using the first‐order local wavenumber approach without the need for third‐order derivatives of the field. Our method is based on normalization of the first‐order local wavenumber anomalies and provides a generalized equation to estimate the depth of some 2D magnetic sources regardless of the source structure. Information about the nature of the sources is obtained after the source location has been estimated. The method was tested using synthetic magnetic anomaly data with random noise and using three field examples.     

On the relative performance of spectrum superposition methods considering modal interaction effects

The contribution of modal interaction in the various available spectrum superposition methods is accounted via the modal cross-correlation coefficient, which has been defined in several different approximate ways. Further, in these methods, to define the final expressions directly in terms of the response spectrum amplitudes, the peak factors for all the modal responses are approximated to be equal to the peak factor for the total structural response. However, these assumptions have been found to be violated significantly in many cases and do not hold good in general. Therefore, some recent studies have attempted to improve upon these assumptions. In this paper, detailed investigations are made to study the relative performance of the various available methods considering the modal interaction effects. To find out which of the available methods, in general, gives the better results, the response of a five-storey asymmetric hypothetical building, characterized by significant interaction effects, has been computed from different methods for several widely differing input excitations and the results have been compared with the exact time-history solution.     

On the physical model of earthquake precursor fields and the mechanism of precursors＇timespace distribution──origin and evidences of the strong body earthquake──generating model

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