A complex analysis approach to the motion of uniform vortices

A new mathematical approach to kinematics and dynamics of planar uniform vortices in an incompressible inviscid fluid is presented. It is based on an integral relation between Schwarz function of the vortex boundary and induced velocity. This relation is firstly used for investigating the kinematics of a vortex having its Schwarz function with two simple poles in a transformed plane. The vortex boundary is the image of the unit circle through the conformal map obtained by conjugating its Schwarz function. The resulting analysis is based on geometric and algebraic properties of that map. Moreover, it is shown that the steady configurations of a uniform vortex, possibly in presence of point vortices, can be also investigated by means of the integral relation. The vortex equilibria are divided in two classes, depending on the behavior of the velocity on the boundary, measured in a reference system rotating with this curve. If it vanishes, the analysis is rather simple. However, vortices having nonvanishing relative velocity are also investigated, in presence of a polygonal symmetry. In order to study the vortex dynamics, the definition of Schwarz function is then extended to a Lagrangian framework. This Lagrangian Schwarz function solves a nonlinear integrodifferential Cauchy problem, that is transformed in a singular integral equation. Its analytical solution is here approached in terms of successive approximations. The self-induced dynamics, as well as the interactions with a point vortex, or between two uniform vortices are analyzed.     

Precast industrial buildings in Southern Europe: loss of support at frictional beam-to-column connections under seismic actions

This paper presents the evaluation of the loss-of-support conditions in frictional beam-to-column connections of industrial precast concrete buildings under seismic actions. This type of connection is widespread throughout Southern Europe in non-seismically designed industrial precast buildings. First, geometric properties of industrial precast buildings and of the frictional beam-to-column connections, together with reference values for the friction coefficient, are reviewed. Then, earthquake time histories taken from the European Strong-Motion sets and recordings of the two major shocks of the 2012 Emilia-Romagna events are presented and discussed showing the importance of the vertical component. Two dynamic models of increasing complexity are used to ascertain loss-of-support conditions under seismic action. The first model is an elastic one, representing a single frame of the industrial buildings. Results are obtained according to: (1) 2D analyses, disregarding the time correlation between the response peaks along the horizontal and vertical directions, (2) 2D analyses taking into account time correlation, and (3) 3D analyses to evaluate also directionality effects. The second model is a 2D non-linear planar frame developed within the OpenSees framework. Results show that simplified (linear) models are a good proxy to more refined (non-linear) ones. However, one must resort to non-linear models if differential displacements between beam and column are of interest. The non-linear numerical investigations show that friction coefficient, horizontal and vertical periods and damping, and column reinforcement ratio are the key variables in estimating the loss-of-support conditions.     

Glacial Isostatic Adjustment and Contemporary Sea Level Rise: An Overview

Glacial isostatic adjustment (GIA) encompasses a suite of geophysical phenomena accompanying the waxing and waning of continental-scale ice sheets. These involve the solid Earth, the oceans and the cryosphere both on short (decade to century) and on long (millennia) timescales. In the framework of contemporary sea-level change, the role of GIA is particular. In fact, among the processes significantly contributing to contemporary sea-level change, GIA is the only one for which deformational, gravitational and rotational effects are simultaneously operating, and for which the rheology of the solid Earth is essential. Here, I review the basic elements of the GIA theory, emphasizing the connections with current sea-level changes observed by tide gauges and altimetry. This purpose is met discussing the nature of the “sea-level equation” (SLE), which represents the basis for modeling the sea-level variations of glacial isostatic origin, also giving access to a full set of geodetic variations associated with GIA. Here, the SLE is employed to characterize the remarkable geographical variability of the GIA-induced sea-level variations, which are often expressed in terms of “fingerprints”. Using harmonic analysis, the spatial variability of the GIA fingerprints is compared to that of other components of contemporary sea-level change. In closing, some attention is devoted to the importance of the “GIA corrections” in the context of modern sea-level observations, based on tide gauges or satellite altimeters.     

An incentive mechanism for reducing emissions from conversion of intact and non-intact forests

This paper presents a new accounting mechanism in the context of the UNFCCC issue on reducing emissions from deforestation in developing countries, including technical options for determining baselines of forest conversions. This proposal builds on the recent scientific achievements related to the estimation of tropical deforestation rates and to the assessment of ‘intact’ forest areas. The distinction between ‘intact’ and ‘non intact’ forests used here arises from experience with satellite-based deforestation measurements and allows accounting for carbon losses from forest degradation. The proposed accounting system would use forest area conversion rates as input data. An optimal technical solution to set baselines would be to use historical average figures during the time period from 1990 to 2005. The system introduces two different schemes to account for preserved carbon: one for countries with high forest conversion rates where the desired outcome would be a reduction in their rates, and another for countries with low rates. A ‘global’ baseline rate would be used to discriminate between these two country categories (high and low rates). For the hypothetical accounting period 2013–2017 and considering 72% of the total tropical forest domain for which data are available, the scenario of a 10% reduction of the high rates and of the preservation of low rates would result in approximately 1.6 billion tCO₂ of avoided emissions. The resulting benefits of this reduction would be shared between those high-rate countries which reduced deforestation and those low-rate countries which did not increase their deforestation over an agreed threshold (e.g., half of “global” baseline rate).     

Die Eigenschwingungen der durch den Kanal im Damm von Melide gekoppelten Becken des Luganersees

The northern and the southern basin of Lake Lugano, Switzerland, are separated by an artificial dam. The flow of the water is not only influenced by the outflow of the northern basin but also by gravitational oscillations (seiches) of both basins. A longperiodic peak around 100 minutes can be explained by a mathematical model. The interaction of the internal waves is a coupled oscillation with a period of 74 hours.      

Integrated approach to choosing suitable areas for the realization of productive wells in rural areas of sub-Saharan Africa

Abstract

Comprehensive geological, hydrogeological and hydrogeochemical investigations were carried out in the south of Hodh El Chargui (southeast Mauritania). Obtaining a hydrogeological conceptual model is crucial for groundwater resources development and management. This is especially true in developing countries and in the rural areas of sub-Saharan Africa. The chosen areas are represented by lithologies referring to a long geological time frame, dating from the Upper Neoproterozoic to the Quaternary age. We developed a methodology in order to identify sites that were suitable for the realization of productive, protected and correct wells to supply safe water to the rural community. A multicriteria approach to studying hydrogeology was used in the project area. In order to identify some main areas in which to carry out pilot interventions, criteria relating to water accessibility and availability, and to hydrogeological and water quality, were considered. Moreover, during the project, it was possible to transfer know-how and hand over responsibilities to the local population and bodies.

Citation Ghiglieri, G. & Carletti, A. (2010 Ghiglieri, G., Balia, R., Oggiano, G. and Pittalis, D. 2010. Prospecting for safe (low fluoride) groundwater in the Eastern African Rift: the Arumeru District (Northern Tanzania). Hydrol. Earth System Sci., 14: 1081–1091.  [Google Scholar]) Integrated approach to choosing suitable areas for the realization of productive wells in rural areas of sub-Saharan Africa. Hydrol. Sci. J. 55(8), 1357–1370.     

Fourier spectrum of the seiches of an ideal rectangular basin with sinusoidally varying level

Summary If the level of an ideal rectangular water basin varies sinusoidally with amplitude 2h ₁ and angular frequency ₀ the modes of the free oscillations of the basin split into multiplets with spacing ₀: the shape and the height of the peaks are given as functions of the mean levelh ₀ and of the lengthl of the basin and of the amplitude 2h ₁.Istituto di Geodesia e Geofisica, Universita' di Trieste, Italy.- This research has been supported by E.R.O.-U.S. Army, under contract DA-91-591-3538.     

Über einen Zusammenhang zwischen atmosphärischen und kosmischen Phänomenen und physikalisch-chemischen Prozessen

Zusammenfassung Sei langer Zeit wird ein Zusammenhang zwischen atmosphärischen und kosmischen Vorgängen und physikalisch-chemischen biochemischen und biologischen Prozessen angenommen. Für Forschungen auf diesem Gebiete hat der Verfasser eine ganz einfache, differentialle Methode ausgearbeitet. Es werden Serien-Fällungen von BiOCl gleichzeitig mit normalem und mit physikalisch aktiviertem Wasser bei identischen Bedingungen gemacht; dabei wird die Anzahl der schnelleren und die Anzahl der langsameren Fällungen im aktivierten Wasser gezählt. Die zeitlichen Änderungen des Prozentsatzes der schnelleren Fällungen werden verfolgt. Die Experimente wurden unter zwei verschiedenen Bedingungen ausgeführt: 1. in einem ganz metallfreien Raum und 2. in einem mit Metall abgeschirmten Raum. Die Unterschiede der Ergebnisse beweisen, daß die registrierten Variationen tatsächlich auf Einwirkungen äußerer Faktoren zurückzuführen sind.Es wurde festgestellt: eine säkuläre Variation, die möglicherweise in Zusammenhang mit der Sonnenaktivität steht; eine jährliche Variation, die man vielleicht mit der Erdbewegung in Verbindung bringen kann; und mehrere kleinere Variationen, die mit verschiedenen Elementen in Zusammenhang stehen können. Es werden Korrelationen mit dem Luftdruck, mit dem luftelektrischen Potentialgefälle und mit der kosmischen Strahlungsintensität festgestellt. Ferner zeigt sich, daß die Beschaffenheit des Metallschirmes von Bedeutung ist. Aus in Florenz, Brüssel und Wien durchgeführten Beobachtungen ließ sich ein Breiteneffekt feststellen. Die Untersuchung der Wirkung der Metallabschirmungan sich mit einem vereinfachten Test ohne Aktivierung ergab, daß im Allgemeinen die BiOCl-Fällung unter Abschirmung schneller erfolgt und daß ein Zusammenhang zwischen der spezifischen elektrischen Leitfähigkeit der verwendeten Metalle und dem Abschirmungseffekt besteht.

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Summary It is commonly believed for a long time that there exists a relation between atmospheric and cosmic phenomena and physico-chemical, biochemical and biological processes. The author has developed a simple and differential method for researches in this field. Series of precipitations with BiOCl are simultaneously made with normal and with activated water at identical conditions, whereby is counted the number of the faster and of the slower precipitations in the activated water; the temporal variations of the percentage of the faster precipitations are studied. The experiments have been carried out with the following two conditions: (1) in a room free of any metal, (2) in a room isolated with metal. The differences in the results prove that the variations obtained are due in fact to the influence of exterior factors.Has been ascertained: a secular variation which might be in connexion with the sunspot activity, an annual variation which might be in connexion with the earth's rotation, and several smaller variations which may be in relation with different elements. There are found correlations with the atmospheric pressure, with the potential gradient of atmospheric electricity and with the intensity of cosmic radiation. Is found, in addition, that the nature of the metal screen is of importance. It was determined also an effect of latitude from observations carried out at Florence, Brussels and Vienna. The investigation of the effect of the metal screen, by a simplified test without activation, has shown that in general the BiOCl precipitation is going on more rapidly when using the screen, and that there is a relation between the specific electrical conductivity of the metals used and the effect of screening.

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Résumé Depuis longtemps on a envisagé une relation entre les phénomènes atmosphériques, solaires et cosmiques et les phénomènes physicochimiques, biochimique set biologiques L'auteur a développé un test inorganique pour l'étude de cette relation. Il fait simplement précipiter par séries dans des conditions identiques, du BiOCl avec de l'eau normale et avec de l'eau activée. Le pourcentage des cas dans lesquels la précipitation marche plus vite dans l'eau activée (T%) est la réponse du test inorganique. L'auteur a conduit ses essais contemporairement au-dehors et au-dedans d'une chambre de cuivre. Les différences dans les résultats obtenus prouvent que les variations observées sont vraiment dûes aux influences exercées par des facteurs extérieurs.On a constaté qu'il existe a) une variation séculaire qui est probablement en rapport avec l'activité solaire, b) une variation annuelle qui peut être due au mouvement de la terre, c) plusieurs autres variations plus petites qui peuvent dépendre de différents éléments. On remarque des corrélations avec la pression atmosphérique, le gradient du potentiel électrique de l'air et l'intensité du rayonnement cosmique. D'autre part, on constate qu'il est important de tenir compte de la nature de l'écran métallique. On a aussi constaté qu'il existait un effet de latitude en comparant les observations faites à Florence, Bruxelles et Vienne. En utilisant un test simplifié sans activation (Test P) l'auteur a montré qu'en général la précipitation se produit plus rapidement au-dessous de l'écran et qu'il existe une relation entre la conductibilité électrique spécifique des métaux employés et l'effet observé.

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Mit 10 Textabbildungen.     

The relationship between websterite and peridotite in the Balmuccia peridotite massif (NW Italy) as revealed by trace element variations in clinopyroxene

 Field, mineralogical and petrological data are presented on a newly found carbonatite occurrence associated with “kamafugite” lava at Cupaello, central Italy. This carbonatite occurrence is part of the Late Pleistocene Umbria-Latium ultra-alkaline district (ULUD) which extends southwards within the Apennines to Mount Vulture, delineating an important magmatic province along the most peripheral belt of the Tyrrhenian extensional tectonic system. This province is distinct, but probably related genetically with the more abundant and common leucite-bearing assemblages of the Roman Comagmatic Region and represents the first reported occurrence of carbonatite assemblages in the Mediterranean Basin. The Cupaello suite indicates that primary or near-primary mantle silicate melts of “kamafugitic” composition are transitional with Ca-carbonatite liquid and provides direct evidence of immiscibility of carbonatite from “kamafugite” magma. It is inferred that a primary mantle origin of Ca-carbonatites is conditional upon a potential silicate magma that may be coupled with the carbonatite, but may not have reached the surface. The data indicate a strong genetic link between ULUD Ca-carbonatites and some African analogues, supporting the view that their genesis depends on similar source and associated tectonic conditions. Received: 17 January 1995 / Accepted: 14 June 1995     

Radiometric age evidences of a Triassic Thermal Event in the Southern Alps

In the Southern Alps several K/Ar age determinations point out the existence of a thermal event of Upper-Triassic age. Radiometric evidences concern overprinting on K/Ar ages of biotites belonging to hercynian periadriatic massives, and of muscovites of pegmatites in which also a Sr isotopic re-equilibration has taken place. Some evidences are also recognizable in ancient metamorphic basement. In the same time an extensive extrusive and intensive magmatic activity of alkaline affinity occurred. These facts are interpreted as predrift events shortly preceeding the set up of lower Jurassic oceanic conditions of alpine area.