Zum Anteil des Faraday-Sohncke-Effekts am Zustandekommen der Gewitterelektrizität     

Franz Wolf 《Meteorology and Atmospheric Physics》1956,9(2):242-263

Zusammenfassung Eine Übersicht über die bisher vorgeschlagenen Quellen für die Gewitterelektrizität zeigt, daß diese den Erfordernissen der Wirklichkeit kaum genügen. Daher wird der Versuch gemacht, das Zustandekommen des unteren positiven Raumladungsgebiets im Gewitter auf die Aufladung zurückzuführen, die Hagelkörner während ihres Wachstums aus Wolkentröpfchen im Aufwind durch den Faraday-Sohnckeschen Tropfenzerreißeffekt erfahren. Quantitative Ausrechnung der Ladung eines Hagels und der gesamten Ladungsproduktion einer aktiven Gewitterzelle sowie Abschätzung aller wesentlichen Einflüsse im wirklichen Cumulonimbus führen zu Gesamtleistungen des Effekts, mittels deren gerade eben der Blitzmechanismus eines bescheidenen Gewitters erklärt werden kann. Der Vorgang ist aber in der gewählten Form einstweilen viel zu schwach, um auch für die außerordentlich großen Verlustströme durch Niederschlag und Ionenabwanderung aufkommen zu können.

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Summary A survey of the sources of thunderstorm electricity taken into consideration up to now shows that they are scarcely sufficient when confronted with the requirements of reality. An attempt has been made, therefore, to account for the origin of the lower positive space-charge region in thunderstorms by the fact that hailstones accept an electric charge by the Faraday-Sohncke-effect when growing from cloud droplets in upwind. Quantitative calculation of the charge of a hailstone and of the total production of electricity in an active thunderstorm cell and estimation of all essential influences in a real cumulonimbus lead to a total energy of the effect by which just the lightning mechanism of a modest thunderstorm can be covered. For the present, the process as considered above is much to weak to be made responsible also for the extraordinarily great losses of electricity by precipitation and migration of ions.

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Résumé Les sources de l'électricité orageuse considérées jusqu'ici sont insuffisantes en regard des faits observés. On tente ici de ramener la charge spatiale positive de la partie inférieure du nuage orageux à la charge dont sont le siège les grêlons au cours de leur croissance dans le vent ascendant par suite de l'effet Faraday-Sohncke. le calcul de la charge d'une grêle en formation et de la charge totale d'une cellule orageuse active, ainsi que l'estimation de tous les effets produits au sein du cumulonimbus, conduisent à une valeur correspondant aux décharges d'un modeste orage. Le processus invoqué est toutefois beaucoup trop faible pour tenir compte des pertes considérables dues aux précipitations et au transport d'ions.

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Why cone models can represent the elastic half-space     

Jethro W. Meek  John P. Wolf 《地震工程与结构动力学》1993,22(9):759-771

In lieu of the rigorous elastodynamical approach, many problems in foundation dynamics may be solved quite accurately via simple cone models of the soil. Although these cone models are amenable to very simple analysis, they have not yet been widely accepted in engineering practice. The reservations against their use are possibly due to the fact that cones are based on non-rigorous strength-of-materials assumptions, they neglect large portions of the half-space, and cannot represent Rayleigh surface waves. These potential objections are investigated step by step and proven to be unfounded. It turns out that cone models indeed incorporate and provide valuable insight into all the salient features of rigorous solutions; the aspects omitted by cones are revealed to be of minor physical importance.  相似文献   

Insight on 2D- versus 3D-modelling of surface foundations via strength-of-materials solutions for soil dynamics     

John P. Wolf  Jethro W. Meek 《地震工程与结构动力学》1994,23(1):91-112

To simplify the analysis, three-dimensional soil–structure interaction problems are often modelled by considering a two-dimensional slice without changing the material properties of the soil. This procedure, although convenient, is of questionable validity because two-dimensional modelling inherently overestimates the radiation damping for translational and rocking motions. To make matters worse, two-dimensional modelling always entails an underestimation of the dynamic-spring coefficient for the translational motions. The damping ratio of the two-dimensional case, which is proportional to the ratio of the damping coefficient to the spring coefficient, will thus be even larger. Thus, reliance upon a two-dimensional analysis based on an equivalent slice of a strip foundation may result in a dangerously non-conservative design. Valuable insights into the essence of radiation damping and the difference between two-dimensional and three-dimensional models may be obtained via approximate strength-of-materials solutions based on cone–wedge models and travel-time considerations. By examining the decay of the waves along the axes of the cone–wedge models, the essence of radiation damping can be grasped. The heuristic concept of more spreading of waves in three dimensions than in two is misleading. Indeed, just the opposite is true: The less the amplitude spreads and diminishes with distance, the greater is the radiation damping. Because the damping ratio is grossly overestimated, two-dimensional modelling of a three-dimensional case cannot be recommended for actual engineering applications. It is more feasible to take the opposite approach and idealize slender soil–structure interaction problems with a radially symmetric model. As an alternative, when defining the equivalent slice of the two-dimensional strip foundation, the impedance of the soil can be changed to achieve a much better agreement of the high-frequency limits of the damping coefficients. In the low-frequency range this modified two-dimensional model also overestimates radiation damping, although to a lesser extent. As a by-product, the dimensions of the equivalent slice of a two-dimensional strip foundation are discussed; and equations for the aspect ratios determining the opening angles of the corresponding wedges are derived. Also addressed is the quite separate but related topic of the transition from square to slender rectangular foundations.  相似文献   

Rotational cone models for a soil layer on flexible rock half-space     

John P. Wolf  Jethro W. Meek 《地震工程与结构动力学》1994,23(8):909-925

The unfolded cone model used for calculating the dynamic response of a disk on the surface of a soil layer resting on flexible rock for translational motion is extended to rotational motion. The method is analogous to that for a layer on rigid rock, the only modification being that the reflection coefficient – α replaces the coefficient of total reflection – 1. The modified value of – α, which, in general, is frequency-dependent, is determined by considering one-dimensional wave propagation along the cone for the first impingement at the layer–rock interface. The low- and high-frequency limits of – α for the rotational motion are the same as for translational motion. As these limits do not depend on frequency, the dynamic analysis using cones can be performed in the familiar time domain. The transfer function constructed by addressing the reflections–refractions at the soil–rock interface and the reflections at the free surface in the unfolded cone model is highly accurate, resulting in the same accuracy of the dynamic response of a disk on a layer resting on flexible rock as that on a homogeneous half-space modelled with a cone.  相似文献   

Zur selektiven Entfernung von Hydrogencarbonationen aus wäßrigen,Chlorid und Hydrogencarbonationen enthaltenden Lösungen mittels Ionenaustauscherharzen (Desalprozeß)     

F. Wolf  K. M. Jamil 《洁净——土壤、空气、水》1976,4(2):173-178

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Moon and Earth : compositional differences inferred from siderophiles,volatiles, and alkalis in basalts     

Rainer Wolf  Edward Anders 《Geochimica et cosmochimica acta》1980,44(12):2111-2124

We have compared RNAA analyses of 18 trace elements in 25 low-Ti lunar and 10 terrestrial oceanic basalts. According to Ringwood and Kesson, the abundance ratio in basalts for most of these elements approximates the ratio in the two planets.Volatiles (Ag, Bi, Br, Cd, In, Sb, Sn, Tl, Zn) are depleted in lunar basalts by a nearly constant factor of 0.026 ± 0.013, relative to terrestrial basalts. Given the differences in volatility among these elements, this constancy is not consistent with models that derive the Moon's volatiles from partial recondensation of the Earth's mantle or from partial degassing of a captured body. It is consistent with models that derive planetary volatiles from a thin veneer (or a residuum) of C-chondrite material; apparently the Moon received only 2.6% of the Earth's endowment of such material per unit mass.Chalcogens (Se and Te) have virtually constant and identical abundances in lunar and terrestrial basalts, probably reflecting saturation with Fe(S, Se, Te) in the source regions.Siderophiles show diverse trends. Ni is relatively abundant in lunar basalts (4 × 10^?3 × Cl-chondrites), whereas Ir, Re, Ge, Au are depleted to 10^?4?10^?5× Cl. Except for Ir, these elements are consistently enriched in terrestrial basalts: Ni 3 × , Re 370 ×, Ge 330 × , Au 9 × . This difference apparently reflects the presence of nickel-iron phase in the lunar mantle, which sequesters these metals. On Earth, where such metal is absent, these elements partition into the crust to a greater degree. Though no lunar mantle rock is known, an analogue is provided by the siderophile-rich dunite 72417 (~0.1% metal) and the complementary, siderophile-poor troctolite 76535. The implied metal-siderophile distribution coefficients range from 10⁴ to 10⁶, and are consistent with available laboratory data.The evidence does not support the alternative explanation advanced by Ringwood—that Re was volatilized during the Moon's formation, and is an incompatible element (like La or W⁴⁺) in igneous processes. Re is much more depleted than elements of far greater volatility: (Re/U)_Cl～- 4 × 10^?6 vs (T1/U)_Cl = 1.3 × 10^?4, and Re does not correlate with La or other incompatibles.Heavy alkalis (K, Rb, Cs) show increasing depletion with atomic number. Cs/Rb ratios in lunar basalts, eucrites, and shergottites are 0.44, 0.36, and 0.65 × Cl, whereas the value for the bulk Earth is 0.15–0.26. These ratios fall within the range observed in LL and E6 chondrites. supporting the suggestion that the alkali depletion in planets, as in chondrites, was caused by localized remelting of nebular dust (= chondrule formation). Indeed, the small fractionation of K, Rb and Cs, despite their great differences in volatility, suggests that the planets, like the chondrites, formed from a mixture of depleted and undepleted material, not from a single, partially devolatilized material.  相似文献   

Seismic response due to travelling shear wave including soil-structure interaction with base-mat uplift     

J. P. Wolf 《地震工程与结构动力学》1977,5(4):337-363

The seismic response due to a travelling shear wave is investigated. The resulting input consists of a translational-and a torsional-acceleration time history, which depend on the ratio of the wavelength to the dimension of the footing. A nuclear reactor building is used for illustration. The combined result of the translational and torsional elastic response (the latter arises even in an axisymmetric structure) will not, in general, be larger than that encountered in the case of a spatially uniform earthquake. If the footing slips or becomes partially separated from the soil, a non-linear dynamic analysis has to be performed to determine the response. Substantial motions in all three directions will take place. The peak structural responses and the floor-response spectra are found to be highly non-linear for high acceleration input values.  相似文献   

Response of a nuclear power plant on aseismic bearings to horizontally propagating waves     

John P. Wolf  Pius Obernhuber  Benedikt Weber 《地震工程与结构动力学》1983,11(4):483-499

The nuclear island of Koeberg with a large basemat, a non-linear base isolation effective in the horizontal direction only, founded on rock, is analysed for inclined body waves and for a combination of surface and body waves associated with prescribed horizontal and vertical components of the control motion. When compared to vertical incidence, an additional rocking component arises, generated by the horizontally propagating vertical component. As the aseismic bearings do not isolate against this rocking component, the corresponding horizontal response bears comparison with that of a conventional structure. The ratio of the response for horizontally propagating waves and that for vertically incident waves is thus considerably larger for the base-isolated structure than for a conventional one. However, the actual design incorporating other loading cases is affected much less.  相似文献   

Field criteria for epigenetic-supergene versus sedimentary-diagenetic silica concentrations in cretaceous limestones,Chihuahua, Mexico     

Karl H. Wolf 《Sedimentary Geology》1972

The Cretaceous limestones of Chihuahua, Mexico, exhibit both sedimentary-diagenetic and epigenetic-supergene silica deposits which are distinguished from each other on the basis of texture/fabric/structure, composition, colour, presence or absence of certain other minerals such as malachite and/or hematite, structural relationships with the host-rock, and general paragenetic characteristics with each other; all described herein. The criteria offer a useful composite working model during field work.  相似文献   

Preliminary studies of food habits of juvenile fish,China Poot Marsh and Potter Marsh,Alaska, 1978     

Edward G. Wolf  Barbara Morson  Kenneth W. Fucik 《Estuaries and Coasts》1983,6(2):102-114

During the year 1978, juvenile salmonids were collected from coastal streams running through China Poot Marsh and the stomach contents analyzed. Stomach contents of threespine stickleback (Gasterosteus aculeatus) and staghorn sculpin (Leptocottus armatus) from China Poot and of threespine stickleback from Potter Marsh were also analyzed; these two species were generally caught in tidal pools on the marshes. The juvenile coho salmon (Oncorhynchus kisutch) had the most varied diet; 37 different prey items were identified in the stomachs. By comparison, 25, 26, and 33 prey taxa were identified in the stomach contents of Dolly Varden char (Salvelinus malma), threespine stickleback, and staghorn sculpin, respectively. Amphipods were the dominant prey of all fish collected from China Poot Marsh; chironomidae larvae were the most common item in the stomach contents of threespine stickleback from Potter Marsh. The diets of all species changed over the course of the study period; the change was most dramatic for juvenile salmonids and sculpins.  相似文献