On the basic principles of geophysical radioactive measurements     

P. Márton  L. Stegena 《Pure and Applied Geophysics》1962,53(1):55-64

Summary The process of radon diffusion in space and time through rocks is treated in detail from the point of view of radiometric prospecting for oil. Taking into account the depth and diffusivity conditions encountered in nature it is stated that vertical radon diffusion reaching from the oil deposits up to the surface cannot be expected. Time intervals as required for setting in of a stationary concentration state and decay conditions of the radon lead to the conclusion that the penetration of emanometric measurements seldom exceeds the depth of 5–10 m.  相似文献   

Zur Ermittlung der bestanschmiegenden Ebene zu einer Anzahl von,aus Erdbeben bestimmten Richtungen     

A. Tárczy-Hornoch 《Pure and Applied Geophysics》1962,52(1):53-58

Zusammenfassung Es werden mit Hilfe der sphärischen Trigonometrie und der Ausgleichsrechnung Methoden angegeben, die die Berechnung der bestanschmiegenden Ebene an eine Anzahl von Geraden mit einem gemeinsamen Punkt ermöglichen.

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Summary With the aid of the spherical trigonometry and the adjustment, methods are given to determin the best-fitting plane for a given set of directions through a common point.

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Astronomische Bestimmung der Relativen Lotabweichungen im Westlichen Tatragebiet     

Josef Kabeláč 《Studia Geophysica et Geodaetica》1962,6(1):1-13

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A simple theoretical interpretation of the cloud system in a dying cyclone from the aspect of the boucher-newcomb model     

Pavla Hlachová  Vojtěch Vítek 《Studia Geophysica et Geodaetica》1966,10(4):481-483

Резюме С помощью принятия простых кинематических предположений и на основании ω—уравнения выла определена конфигурация полос облаков в полностью окклюдированном циклоне без фронтов. Облачная система определяется полем скрытой теплоты, выделяемой в процессах конденсации. Полосы облаков теоретически представляют собой в основном листы синусоидальной спирали.

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Address: Boční II, Praha 4-Spořilov.  相似文献   

Waveform Shaping of Sonar Transducers for Improving the Vertical Resolution in Sub-bottom Sediments Profiling     

P. Cobo  C. Ranz  A. Fernández  M. Cuesta  D.K. Anthony  M. Siguero 《Marine Geophysical Researches》2005,26(2-4):87-95

Vertical resolution is of fundamental importance in sonar exploration and is directly related to the duration of the acoustic pulse generated by the transducer. The shorter the radiated pulse, the higher the vertical resolution. Many sub-bottom profiling sonar systems use piezoelectric transducers because they are reversible and well understood. Piezoelectric projectors are normally resonant transducers, which are intrinsically narrowband. A piezoelectric transducer is usually driven by a tone-burst. However, it is possible to use Fourier techniques to find a pre-compensated electrical driving function so that the transducer radiates a prescribed wider band acoustic waveform. This technique can be applied to synthesize zero-phase cosine-magnitude, Gaussian, and bionic pulses, with a conventional sandwich transducer. Zero-phase cosine-magnitude waveforms provide minimum length pulses (and therefore maximum resolution) within a prescribed frequency band.The aim of this paper is to illustrate the synthesis of wideband acoustic pulses using an underwater piezoelectric projector. The conventional acoustic waveform radiated when a Tonpiltz transducer is transiently excited using a “click” and allows its frequency response function to be measured. This function is used to design the electrical signal which then drives the transducer so that it radiates the shortest pulse compatible with its mechanical response. The significant resolution enhancement of the waveform shaping process is illustrated by its application to a sediment wedge model.  相似文献   

Measuring and modelling temporal trends of 226Ra in waters of a Spanish estuary affected by the phosphate industry     

Periáñez R 《Marine environmental research》2005,60(1):35-49

The presence and temporal evolution (1990-2001) of (226)Ra in a tidal estuary affected by the phosphate industry has been investigated. Water samples collected in the course of four separate sampling campaigns were analysed for (226)Ra content using a gas flow proportional counter following Ba coprecipitation. Two (226)Ra sources have been identified: direct discharges from the industrial complex and run-off from a phosphogypsum pile. Although activity levels are similar, or even higher, than those found in other environments affected by the phosphate industry, there has been a general decrease in contamination since direct discharges ceased in 1998 due to new regulations from the EU. However, sediments are now acting as a source of Ra to the water column due to redissolution processes. A numerical model of the estuary has been developed to describe quantitatively the experimental results. The model solves the hydrodynamics and the dispersion equation of (226)Ra including interactions with sediments. Model results are, in general, in good agreement with observations.  相似文献   

The European vision for oceans and seas—Social and political dimensions of the Green Paper on Maritime Policy for the EU     

Juan Luis Suárez de Vivero 《Marine Policy》2007

The EU Green Paper on Maritime Policy is the European response to the new generation of ocean strategies based on science, technology and innovation aimed at new objectives, such as the strengthening of security and access to new resources. The European character of the proposal is found in the presence of social, cultural and historical elements, what is called the “European vision”. The viability of a European vision of the oceans and the idea of maritime empire as an extension of the current concept of empire within the general context of emerging ocean strategies are the elements offered up for debate on this European Union initiative.  相似文献   

An aromatase inhibitor and tamoxifen decrease plasma levels of o,p'-DDT and its metabolites in Nile tilapia (Oreochromis niloticus)     

Leaños-Castañeda O  Gold-Bouchot G  Van Der Kraak G  Lister A  Ceja-Moreno V  Simá-Alvarez R 《Marine environmental research》2004,58(2-5):337-342

The objective of this study was to determine if tamoxifen or an aromatase inhibitor (4-hydroxyandrostenedione; 4-OHA) affected plasma concentrations of o,p' -DDT and its metabolites, o,p'-DDD and o,p'-DDE, in mature tilapia. Male and female tilapia were injected 6 times intraperitoneally with o,p'-DDT (40 mg/kg) alone or in combination with 4-OHA (2 mg/kg) over a 12 day period. An additional group of male fish was injected with tamoxifen (5 mg/kg) plus o,p'-DDT. At the end of the treatment period, plasma samples were extracted and analyzed by GC/ECD. Females injected only with o,p'-DDT had significantly higher levels of o,p'-DDT compared with males. Interestingly, females and males treated concomitantly with o,p'-DDT and 4-OHA or tamoxifen had significantly lower concentrations of plasma o,p'-DDT (about 50%) compared with fish treated with only o,p'-DDT. These initial results suggest that an interaction between endocrine-active compounds occurs in vivo in tilapia and may involve alterations in metabolism of o,p'-DDT.  相似文献   

A comparative mineralogical study of gas-related sediments of the Gulf of Cádiz     

C. Martín-Puertas  M. P. Mata  M. C. Fernández-Puga  V. Díaz del Río  J. T. Vázquez  L. Somoza 《Geo-Marine Letters》2007,27(2-4):223-235

The Gulf of Cádiz area has been extensively surveyed in recent years and several gas-related fluid escape seafloor structures have been identified. In this study, gravity cores, collected during the ANASTASYA/00 and ANASTASYA/01 cruises, on mud volcanoes, hemipelagic sediments and dredged material from diapiric structures, have been studied. A comparative mineralogical analysis by XRD and SEM of samples from different areas has been performed in order to determine whether there is a characteristic mineralogy related to these fluid escape structures, and also to determine the origin of the mud matrix and constrain the depth of the parent units. The mineralogical analysis reflects the different origins of the different units described in the cores: hemipelagic material of the slope, clays that underlie the mud volcanoes and are discharged at the sea bottom surface, and authigenic and diagenetic minerals possibly involved in the anaerobic oxidation of methane in the mud volcano sediments.  相似文献   

A probability distribution for depth-limited extreme wave heights in a sea state     

Fernando J. Mndez  Sonia Castanedo 《Coastal Engineering》2007,54(12):878-882

A model for the depth-limited distribution of the highest wave in a sea state is presented. The distribution for the extreme wave height is based on a probability density function (pdf) for depth-limited wave height distribution for individual waves [Méndez, F.J., Losada, I.J., Medina, R. 2004. Transformation model of wave height distribution. Coastal Eng, Vol. 50, 97:115.] and considers the correlation between consecutive waves. The model is validated using field data showing a good representation of the extreme wave heights in the surf zone. Some important statistical wave heights are parameterized obtaining useful expressions that can be used in further calculations.  相似文献