Transient chaos and resonant phase mixing in violent relaxation     

Henry E. Kandrup  Ileana M. Vass  Ioannis V. Sideris 《Monthly notices of the Royal Astronomical Society》2003,341(3):927-936

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Shear-Wave Velocity Models From Rayleigh-Wave Dispersion In the Broader Aegean Area   总被引：2，自引：0，他引：2  

Ioannis S. Kalogeras  Paul W. Burton 《Geophysical Journal International》1996,125(3):679-695

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A Preliminary Survey of the Level of Microbiological Pollution of Major Rivers in Northern Greece     

Panagiotis Karanis  Ioannis Chronis  George Zakas  Christina Kourenti  Isaia Sotiriadou  Chrissanthy Papadopoulou 《洁净——土壤、空气、水》2005,33(4):346-354

The objective of the present survey was to assess the microbiological quality of river waters used mainly to irrigate the large plains of Macedonia and Thessaly in Northern Greece. Five rivers (Aliakmonas, Axios, Loudias, Mavroneri and Pineios) were sampled during a 10‐month period (June 2002 – March 2003) for Total Microbial Flora (TMF) at 22 °C and 37 °C, Total Coliforms (TC), Fecal Coliforms (FC), enterococci, staphylococci, Pseudomonas, fungi, Giardia spp. and Cryptosporidium spp. The results indicate moderate to high microbiological pollution, with the highest levels of microbial pollution found in Mavroneri and Pineios Rivers, and moderate pollution levels in Aliakmonas, Axios and Loudias Rivers. The extent of microbiological pollution is accentuated by the fact that Giardia‐ and/or Cryptosporidium cysts were detected in nine out of eleven samples collected in June 2002 with excessive Giardia counts demonstrated for Pineios River. The microbiological pollution of the surveyed rivers is attributed to various degrees of human interference and to lack of ample pollution monitoring systems, which emphasize the need for implementation of the EU Water Framework Directive.  相似文献   

Response of seismically isolated structures to rocking‐type excitations     

Ioannis Politopoulos 《地震工程与结构动力学》2010,39(3):325-342

In this paper, the origin of rocking‐type excitations and their effects on the response of base isolated structures are studied. In particular, the role of kinematic interaction in the determination of the rocking excitation is highlighted. The cases of surface foundations subjected to horizontally propagating waves, as well as of embedded foundations under vertically incident shear waves are examined. The validity of the kinematic interaction based on the rigid base mat assumption is discussed. It is shown that, in the case of classical horizontal isolation, rocking input may amplify significantly the response of the lower non‐isolated modes. The examination of full three‐dimensional isolation and active and semi‐active control methods demonstrates the efficacy of these methods to improve the performance of seismically isolated structures subjected to rocking excitations. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Potential merits for substorm research from imaging of charge-exchange neutral atoms     

Ioannis A. Daglis  Stefano Livi 《Annales Geophysicae》1995,13(5):505-516

The in situ observations of the Earth magnetosphere performed over the past decades of space research have provided a rather good understanding of many partial localized processes of the magnetospheric substorm. The continuing lack of global observations inhibits the construction of a coherent picture of the substorm as a whole, which is actually determined by the coupling of the partial processes. In this context the importance of global observations for the advancement of magnetospheric substorm studies is critical. This paper presents briefly a promising technique of global observations, namely the imaging of charge exchange neutral atoms, or neutral atom imaging (NAI) of the magnetosphere. Model and theoretical estimates of charge-exchange neutral atom fluxes, as well as appropriate spacecraft orbit and instrumentation requirements are presented and discussed for specific regions of interest and vantage points. The potential merits of NAI for substorm research are presented along with possible combinations with other types of observational methods. Substorm issues that would benefit from NAI should include among others the assessment of the ionospheric contribution to the hot magnetospheric plasma, the relative importance of various ionospheric ion source regions, the resolution of spatial and temporal characteristics of substorm ion injections. NAI observations can be precious complements to local observations and lead to the understanding of how local processes, many of which are resolved quite well today, combine to form the global process of the magnetospheric substorm.  相似文献   

Dynamics of flexible systems with partial lift-off     

Ioannis N. Psycharis 《地震工程与结构动力学》1983,11(4):501-521

The dynamic behaviour of a simplified model of a multi-storey building, supported by an elastic foundation and allowed to uplift, is examined. The building is modelled by an n-degree-of-freedom oscillator, while the foundation is represented by a viscously damped two-spring model which permits uplift. This model has been shown in previous studies to be an accurate approximation to the more realistic but more complex Winkler foundation. Approximate values for the characteristic frequencies of the interacting system are presented and a simple, first-mode solution is developed. The response of the system is non-linear and the apparent fundamental period increases with the amount of lift-off. In contrast to the first mode of the superstructure which participates strongly in the interaction, the second and higher modes of the building are not affected significantly by either the interaction with the soil or the uplift. The study shows that lift-off results in larger rocking motion of the structure, but it is not clear from the analysis and the example whether the interfloor displacements are consistently increased or decreased, since this appears to depend on the properties of the system and the excitation.  相似文献   

Tracer methods used to verify the hypothesis of Cvijić about the underground connection between Prespa and Ohrid Lake     

Sokrat Amataj  Todor Anovski  Ralf Benischke  Romeo Eftimi  Laurence L. Gourcy  Liliana Kola  Ioannis Leontiadis  Eftim Micevski  Alqiviadis Stamos  Jovan Zoto 《Environmental Geology》2007,51(5):749-753

Prespa Lake and Ohrid Lake constitute a hydraulic system shared between Albania, FYR of Macedonia and Greece. Karst rocks separate both lakes. The elevation of Prespa Lake is about 150 m higher than that of Ohrid Lake. Considering these facts, Cvijić formulated in 1906 the hypothesis that Prespa Lake recharges the St. Naum and Tushemisht springs at Ohrid lakeside. Environmental isotopes demonstrated that Prespa Lake recharges about 37–42 and 52–54% of water emerging in St. Naum, and Tushemisht springs, respectively. An artificial tracer experiment carried out in 2002 physically demonstrated the underground connection between both lakes. This experiment confirmed the supposed underground connection and brought important information about the groundwater velocity, transit time, and karst water conduits development.  相似文献   

Were Greek temples oriented towards aurorae?     

Ioannis Liritzis  Helen Vassiliou 《Astronomy& Geophysics》2006,47(1):1.14-1.18

Ioannis Liritzis and Helen Vassiliou assess the evidence that the Ancient Greeks saw the aurora borealis, and that it was a rare and special event, strongly enough associated with particular gods to build temples of unusual orientation.  相似文献   

Hydrodynamic,neotectonic and climatic control of the evolution of a barrier beach in the microtidal environment of the NE Ionian Sea (eastern Mediterranean)     

Serafim E. Poulos  George Ghionis  Efthymia Verykiou  Grigoris Roussakis  Dimitrios Sakellariou  Aikaterini Karditsa  George Alexandrakis  Stelios Petrakis  Dafni Sifnioti  Ioannis P. Panagiotopoulos  Periklis Andris  Panos Georgiou 《Geo-Marine Letters》2015,35(1):37-52

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Statistical biases and errors inherent in photoclinometric surface slope estimation with natural light     

Ioannis Bertsatos  Nicholas C. Makris 《Icarus》2010,208(2):798-810

Photoclinometry is the most common method used to obtain high-resolution topographic maps of planetary terrain. We derive the likelihood function of photoclinometric surface slope from (1) the probability distribution of the measured photon count of natural sunlight through a Charge-Coupled Device (CCD) including uncertainty due to camera shot noise, camera read noise, small-scale albedo fluctuation and atmospheric haze, and (2) a photometric model relating photocount to surface orientation. We then use classical estimation theory to determine the theoretically exact biases and errors inherent in photoclinometric surface slope and show when they may be approximated by asymptotic expressions for sufficiently high sample size. We show how small-scale albedo variability often dominates biases and errors, which may become an order of magnitude larger than surface slopes when surface reflectance has a weak dependence on surface tilt. We provide bounds on the minimum possible error of any unbiased photoclinometric surface slope estimate, and compute the sample sizes necessary to constrain errors within desired design thresholds.  相似文献