Long-period fluctuations in ionospheric absorption and their relation with planetary activity in the stratosphere     

D. Pancheva  G. Nestorov  B. De la Morena  Josef Boška  Reviewer J. Laštovička 《Studia Geophysica et Geodaetica》1989,33(1):81-96

Summary By investigating the quasi-regular variations in ionospheric absorption along three distant radio paths with approximately one and the same equivalent frequency during the winters 1983/84 and 1984/85, an attempt is made to study the stratospheric-mesospheric relations at typical geographic mid latitudes. It is shown that the quasi-regular oscillations of ionospheric absorption, investigated in this paper, reach maximum development in each time series at one and the same time. This means, that if they are provoked by an external source when it starts acting, a spectrum of frequencies is generated rather than a definite fixed frequency. By studying the variation of the instantaneous amplitudes of the quasi-regular oscillations in ionospheric absorption with time, their connection with the amplification of the quasi-stationary planetary waves in the stratosphere with a zonal wave number 2 during the winter periods under investigation is shown.

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Резюме Иссле?rt;овaнuем квaзuре улярных вaрuaцuŭ в uоносферном nо лощенuu в mрех nросmрaнсmвенно оm?rt;aленных рa?rt;uо-mрaссaх с nрuблuзumельно о?rt;ноŭ u mоŭ же эквuвaленmноŭ чaсmовоŭ зuмоŭ 1983/84 u 1984/85 . ?rt;елaеmся nоnыmкa uзучumь сmрamосферно-мезос ферные связu в munuчных сре?rt;ных щuроmaх. Покaзaно, чmо рaссмоmренные в рaбоmе квaзuре улярные колебaнuя в uоносферном nо лощенuu ?rt;осmu aюm мaксuмaльно о рaзвumuя в кaж?rt;ом временном ря?rt;у в о?rt;но u mо же время. Эmо ознaчaеm, чmо, еслu онu возбуж?rt;ены внещнuм uсmочнuком, mо nрu е о включенuu енерuруюmся не о?rt;нa чaсmоma, a целыŭ сnекmр чaсmоm. Изученuем временных uзмененuŭ м новенных aмnлumу?rt; квaзuре улярных колебaнuŭ в uоносфермон nо лощенuu зa uссле?rt;овaнные зuмнuе nерuо?rt;ы nокaзaнa uх связь с квaзu-сmaцuонaрнымu nлaнеmaрнымu колебaнuямu в сmрamосфере с зонaльным волновымu чuслом 2.

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暴雨降水强度和历时的面积分布律   总被引：1，自引：2，他引：1  

马力  沙拉买提 《高原气象》1993,12(4):432-436

暴雨的历时，面积和深度的关系（时、面，深）是水文气象学的重要研究课题之一。近年来，从熵最大原理的角度曾推导出其中的两个负指数关系，并被大量的观测所证实。本文通过对５个个例的分析发现，降水过程的另外两组变量也服从负指数关系。即不同的降水历时与其占有的面积之间和不同的降水强度与其占有的面积之间都遵从负指数关系。而这两组新关系显然对暴雨预告有实用价值。  相似文献   

Theoretical validation of ground-based microwave ozone observations     

P. Ricaud  G. Brasseur  J. Brillet  J. de La Noë  J.-P. Parisot  M. Pirre 《Annales Geophysicae》1994,12(7):664-673

Ground-based microwave measurements of the diurnal and seasonal variations of ozoneat 42±4.5 and 55±8 km are validated by comparing with results from a zero-dimensional photochemical model and a two-dimensional (2D) chemical/radiative/dynamical model, respectively. O₃ diurnal amplitudes measured in Bordeaux are shown to be in agreement with theory to within 5%. For the seasonal analysis of O₃ variation, at 42±4.5 km, the 2D model underestimates the yearly averaged ozone concentration compared with the measurements. A double maximum oscillation (\sim3.5%) is measured in Bordeaux with an extended maximum in September and a maximum in February, whilst the 2D model predicts only a single large maximum (17%) in August and a pronounced minimum in January. Evidence suggests that dynamical transport causes the winter O₃ maximum by propagation of planetary waves, phenomena which are not explicitly reproduced by the 2D model. At 55±8 km, the modeled yearly averaged O₃ concentration is in very good agreement with the measured yearly average. A strong annual oscillation is both measured and modeled with differences in the amplitude shown to be exclusively linked to temperature fields.  相似文献   

Research strategies for the improvement of cactuspear (Opuntia ficus-indica) fruit quality and production     

P. Inglese  G. Barbera  T. La Mantia 《Journal of Arid Environments》1995,29(4)

Cactus pear (Opuntia ficus-indica L.) is cultivated worldwide for fruit production either in the subsistence agriculture of dryland areas or as a cash crop. However, little horticultural research has been devoted to this species so far. Research needs related to reproductive biology as well as productivity and orchard management are outlined. A better knowledge of the environmental influence on reproductive biology and fruit quality, the control of fluctuations in plant cropping, as well as the reduction of seed number and size, are the major challenges for future research. Cactus pear will transcend the ethnical markets only if adequate marketing strategies can be promoted and fruit quality enhanced and standardized.  相似文献   

Automation of measuring the temperature dependence of electrical conductivity of rocks using a PMD-85-1 microcomputer     

Marcela Laštovičková  Karel Klíma  Reviewer A. Janáčková 《Studia Geophysica et Geodaetica》1988,32(1):78-83

Summary The new for measuring the electrical conductivity of rocks and minerals developed in the Geophysical Institute is briefly discussed. Unlike the earlier method it uses a PMD-85-1 microcomputer and related equipment (all of CMEA production), which enable the automatic control of the experiment, collection, evaluation, graphic display and storage of the results. This method is verified by measuring the electrical conductivities of granitoids.

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am nua m¶rt; uu mn¶rt;mu n¶rt; u ua ¶rt;a uu umumm . muuu m n¶rt;u¶rt; m¶rt;a unm unmPMD-85-1 u nua¶rt;au nuuu ( nu¶rt;ma ), m nm mm amamu nau numa, , am,au uau u anu mam uu. mm m¶rt; nm n uu mn¶rt;muaumu¶rt;.

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Bibliografia vulcanologica española     

Maximino San Miguel De La Cámara 《Bulletin of Volcanology》1952,12(1):203-214

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Comments on “Floating Pontoon Breakwaters” by A.N. Williams, H.S. Lee and Z. Huang, Ocean Engineering 27 (2000) 221–240     

P. A. A. Laura  C. A. Rossit  S. La Malfa 《Ocean Engineering》2001,28(3):345

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Statistical characterization of active sonar reverberation using extreme value theory   总被引：1，自引：0，他引：1  

La Cour  B.R. 《Oceanic Engineering, IEEE Journal of》2004,29(2):310-316

The statistics of reverberation in active sonar are characterized by non-Rayleigh distributed amplitudes in the normalized matched filter output. Unaccounted for, this property can lead to high false-alarm rates in fixed-threshold detectors. A new approach to modeling threshold-crossing statistics based on extreme value theory is proposed, which uses the generalized Pareto distribution as the unique asymptotic model of the tail distribution, valid at large thresholds. Methods of parameter estimation are discussed and applied to active sonar reverberation collected on a hull-mounted sonar system. The statistics of reverberation in active sonar are found to generally have a power-law behavior in the tails with a shape parameter that is persistent in time and bandwidth dependent. The threshold needed for accurate parameter estimation is generally found to be well below that of typical fixed-threshold detectors.  相似文献   

A practical method to estimate crack openings in concrete structures     

M. Matallah  C. La Borderie  O. Maurel 《国际地质力学数值与分析法杂志》2010,34(15):1615-1633

Numerical modelling of concrete cracking requires robust models able to describe opening and propagation of cracks. Structural concrete codes provide practical relations to describe crack openings. However, these empirical methods were developed for specific structures and cannot be used for general applications. Here, a continuous modelling approach based on damage mechanics is used to compute crack openings in a tie‐beam concrete structure. We propose a post‐processing method to extract crack openings from a continuum damage finite element computation. This method can be applied to all continuum damage/plasticity models. The tie‐beam concrete is characterized by a weak stress gradient; this aspect complicates predictions of crack positions and number. A stochastic method is used to take into account the spatial variability in concrete properties and create a spatially correlated random property field. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

A comparison of the Iberian and Ebro Basins during the Permian and Triassic, eastern Spain: A quantitative subsidence modelling approach   总被引：2，自引：0，他引：2  

Henar Vargas  Jorge M. Gaspar-Escribano  Jos Lpez-Gmez  Jan-Diederik Van Wees  Sierd Cloetingh  Raúl de La Horra  Alfredo Arche 《Tectonophysics》2009,474(1-2):160

The Permian–Triassic sediments of the Iberian Plate are a well studied case of classical Buntsandstein–Muschelkalk–Keuper facies, with good sedimentological interpretations and precise datings based on pollen and spore assemblages, ammonoids and foraminifera. Synrift–postrift cycles are recorded in these facies, but there are only a few studies of quantitative subsidence analysis (backstripping method) and only a previous one using forward modelling for the quantification of synrift–postrift phases of this period.Here we present the results obtained by the quantitative analysis of fourteen field sections and oil-well electric log records in the Iberian and Ebro Basins, Spain. Backstripping analysis showed five synrift phases of 1 to 3 million years duration followed by postrift periods for the Permian–Triassic interval. The duration, however, shows lateral variations and some of them are absent in the Ebro Basin. The forward modelling analysis, assuming local isostatic compensation, has been applied to each observation point using one-layer and two-layer lithospheric configurations. The second one shows a better fit between observation and model prediction in a systematic way, so a two layer configuration is assumed for the sedimentary basin filling analysis. Lithospheric stretching factors β and δ obtained in the forward modelling analysis are never higher than 1.2, but sometimes β < 1 and simultaneously δ > 1 in the same section. If surficial extension is compensated by deep compression either at the roots of the rift basins or in far-away zones is not yet clear, but this anomaly can be explained using a simple shear extensional model for the Iberian and Ebro basins.  相似文献