Instabilities and bifurcations of the families of collision periodic orbits in the restricted three-body problem     

Antonis D. Pinotsis 《Planetary and Space Science》2009,57(12):1389-1404

By using Birkhoff's regularizing transformation, we study the evolution of some of the infinite j-k type families of collision periodic orbits with respect to the mass ratio μ as well as their stability and dynamical structure, in the planar restricted three-body problem. The μ-C characteristic curves of these families extend to the left of the μ-C diagram, to smaller values of μ and most of them go downwards, although some of them end by spiralling around the constant point S* (μ=0.47549, C=3) of the Bozis diagram (1970). Thus we know now the continuation of the families which go through collision periodic orbits of the Sun-Jupiter and Earth-Moon systems. We found new μ-C and x-C characteristic curves. Along each μ-C characteristic curve changes of stability to instability and vice versa and successive very small stable and very large unstable segments appear. Thus we found different types of bifurcations of families of collision periodic orbits. We found cases of infinite period doubling Feigenbaum bifurcations as well as bifurcations of new families of symmetric and non-symmetric collision periodic orbits of the same period. In general, all the families of collision periodic orbits are strongly unstable. Also, we found new x-C characteristic curves of j-type classes of symmetric periodic orbits generated from collision periodic orbits, for some given values of μ. As C varies along the μ-C or the x-C spiral characteristics, which approach their focal-terminating-point, infinite loops, one inside the other, surrounding the triangular points L₄ and L₅ are formed in their orbits. So, each terminating point corresponds to a collision asymptotic symmetric periodic orbit for the case of the μ-C curve or a non-collision asymptotic symmetric periodic orbit for the case of the x-C curve, that spiral into the points L₄ and L₅, with infinite period. All these are changes in the topology of the phase space and so in the dynamical properties of the restricted three-body problem.  相似文献   

The DEEP2 Galaxy Redshift Survey: the red sequence AGN fraction and its environment and redshift dependence     

Antonio D. Montero-Dorta  Darren J. Croton  Renbin Yan  Michael C. Cooper  Jeffery A. Newman  Antonis Georgakakis  Francisco Prada  Marc Davis  Kirpal Nandra  Alison Coil 《Monthly notices of the Royal Astronomical Society》2009,392(1):125-134

We measure the dependence of the active galactic nuclei (AGN) fraction on local environment at   z ∼ 1  , using spectroscopic data taken from the DEEP2 Galaxy Redshift Survey, and Chandra X-ray data from the All-Wavelength Extended Groth Strip International Survey (AEGIS). To provide a clean sample of AGN, we restrict our analysis to the red sequence population; this also reduces additional colour–environment correlations. We find evidence that high-redshift LINERs in DEEP2 tend to favour higher density environments relative to the red population from which they are drawn. In contrast, Seyferts and X-ray selected AGN at   z ∼ 1  show little (or no) environmental dependencies within the same underlying population. We compare these results with a sample of local AGN drawn from the Sloan Digital Sky Survey (SDSS). Contrary to the high-redshift behaviour, we find that both LINERs and Seyferts in the SDSS show a slowly declining red sequence AGN fraction towards high-density environments. Interestingly, at   z ∼ 1  red sequence Seyferts and LINERs are approximately equally abundant. By   z ∼ 0  , however, the red Seyfert population has declined relative to the LINER population by over a factor of ∼4.5. We speculate on possible interpretations of our results.  相似文献   

Geochemistry and Petrogenesis of Post-Collision Pangeon Granitoids in Central Macedonia, Northern Greece     

G. Eleftheriadis  A. Koroneos 《Chemie der Erde / Geochemistry》2003,63(4):364-389

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Interplay between geochemistry and magma dynamics during magma interaction: An example from the Sithonia Plutonic Complex (NE Greece)     

G. Christofides  D. Perugini  A. Koroneos  T. Soldatos  G. Poli  G. Eleftheriadis  A. Del Moro  A.M. Neiva 《Lithos》2007,95(3-4):243-266

Orogenic granitoids often display mineralogical and geochemical features suggesting that open-system magmatic processes played a key role in their evolution. This is testified by the presence of enclaves of more mafic magmas dispersed into the granitoid mass, the occurrence of strong disequilibrium textures in mineralogical phases, and/or extreme geochemical and isotopic variability.

In this contribution, intrusive rocks constituting the Sithonia Plutonic Complex (Northern Greece) are studied on the basis of mineral chemistry, whole-rock major, trace element geochemistry, and Sr and Nd isotopic composition. Sithonia rocks can be divided into a basic group bearing macroscopic (mafic enclaves), microscopic (disequilibrium textures), geochemical, and isotopic evidence of magma interaction, and an acid group in which most geochemical and isotopic features are consistent with a magma mixing process, but macroscopic and microscopic features are lacking.

A two-step Mixing plus Fractional Crystallization (MFC) process is considered responsible for the evolution of the basic group. The first step explains the chemical variation in the mafic enclave group: a basic magma, represented by the least evolved enclaves, interacted with an acid magma, represented by the most evolved granitoid rocks, to give the most evolved enclaves. The second step explains the geochemical variations of the remaining rocks of the basic group: most evolved enclaves interacted with the same acid magma to give the spectrum of rock compositions with intermediate geochemical signatures. A convection–diffusion process is envisaged to explain the geochemical and isotopic variability and the lack of macroscopic and petrographic evidence of magma interaction in the acid group.

The mafic magma is presumably the result of melting of a mantle, repeatedly metasomatized and enriched in LILE due to subduction events, whereas the acid magma is considered the product of partial melting of lower crustal rocks of intermediate to basaltic composition.

It is shown that Sithonia Plutonic Complex offers the opportunity to investigate in detail the complex interplay between geochemistry and magma dynamics during magma interaction processes between mantle and crustal derived magmas.  相似文献   

Algebraic estimation of the specific storage from slug tests in confined aquifers in the overdamped case     

Mazi  Katerina  Akylas  Evangelos  Koussis  Antonis D. 《Hydrogeology Journal》2021,29(7):2545-2553

Hydrogeology Journal - A simple method is presented for estimating the specific storage of a confined aquifer from an overdamped slug test in a fully penetrating well. This method is based on the...  相似文献   

Reply to the Discussion of “Assessment and review of the hydraulics of storage flood routing 70 years after the presentation of the Muskingum method” by M. Perumal     

Antonis D. Koussis 《水文科学杂志》2013,58(8):1431-1441

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Using detrital garnets to determine provenance: a case study from the Vertiskos Unit (Serbomacedonian Massif,N. Greece)     

Ioannis K. Georgiadis  Antonios Koroneos  Lamprini Papadopoulou  Nikolaos Kantiranis  Alexios E. Tamparopoulos  Ananias Tsirambides 《Mineralogy and Petrology》2014,108(2):187-206

Garnet single crystals of several millimeters in diameter were collected from the uppermost horizon of a soil profile developing immediately on the gneissic rocks of the Vertiskos Unit of the Serbomacedonian Massif in northern Greece. The garnets were analyzed for major elements by EDS analyzer mounted on a scanning electron microscope, and the obtained data were utilized to determine their source rocks. Bivariate diagrams, spider diagrams as well as statistical analysis were used in order to correlate and compare the garnet composition of the basement rocks of the Vertiskos Unit with the existing reference data. This case study demonstrates the difficulty in assigning a source rock to sediment, using only the chemical compositional of detrital garnet. Direct linking of the detrital garnets and the outcropping rocks is not always possible despite well documented outcrop lithologies. This is largely due to a complex metamorphic evolution that leads to overlapping compositions between garnets originating from different lithologies that have undergone similar metamorphic processes and alteration effects.  相似文献   

Joint inversion of 2D resistivity and seismic travel time data to image saltwater intrusion over karstic areas   总被引：1，自引：0，他引：1  

Hamdan A. Hamdan  Antonis Vafidis 《Environmental Earth Sciences》2013,68(7):1877-1885

The simultaneous inversion of multiple geophysical data types has been proven to be a powerful tool to both improve subsurface imaging and help in the interpretation process. The main goal of this paper was to develop joint inversion strategies to provide improved resistivity and seismic velocity images for delineating saline water zones in karstic geological formations. The cross-gradient constraint approach was adopted to jointly invert resistivity and seismic first arrival data. The basic idea of this approach is to quantitatively estimate the structural similarity between resistivity and seismic velocity models, using the cross product of their gradients and to achieve a unified geological model which satisfies both data sets. Initially, synthetic data were employed to help develop a joint inversion strategy to be used over such complex geological structures. The proposed strategy uses a weighting factor for the cross-gradient constraints and separate damping factors for the resistivity and seismic data. This strategy was applied successfully on field data from the karstic region of Stilos, Crete, Greece.  相似文献   

Reverse flood and pollution routing with the lag-and-route model     

Antonis D. Koussis  Katerina Mazi 《水文科学杂志》2013,58(10):1952-1966

ABSTRACT

Reverse routing can be used to transfer flood- or pollution-related information monitored at a downstream gauging station to an ungauged upstream cross-section. This signal identification problem is ill-posed and, as such, is sensitive to perturbations in the data to be inverted; therefore, the amplification of errors, e.g., those befalling measurements, must be controlled. Storage routing models are parsimonious diffusion wave substitutes and well suited for conversion to direct reverse routers. We present efficient inversion frameworks based on the lag-and-route (single reservoir plus exact reverse lag-step) and the reservoirs-in-series models. In both cases we invert a centred finite difference scheme of the reservoir storage balance equation that involves only one value of the unknown signal; signal values identified in previous reverse time steps, which would carry perturbations, are absent. This simple structure endows the reverse scheme with robustness. Procedures are verified with perfect and with error-seeded data; solution oscillations caused by the latter are damped by low-pass filtering. Both inverse routing models regain the upstream signals with high fidelity. Reverse storage routing is exemplified in a demonstration of reservoir control and in a field case of solute transport in a stream.