Anaerobic Digestion of Olive Mill Wastewater: Focusing on the Effect of Nitrogen Source     

Ioannis S. Zarkadas  Stavros Zachariou  Ioannis Stamou  Fokion V. Kaldis  Marilena Lioti  Dimosthenis A. Sarigiannis 《洁净——土壤、空气、水》2019,47(3)

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Evaluation of Greek low-rank coals as potential raw material for the production of soil amendments and organic fertilizers     

Andriana Giannouli  Stavros Kalaitzidis  George Siavalas  Adamantia Chatziapostolou  Kimon Christanis  Stefanos Papazisimou  Cassiani Papanicolaou  Antonis Foscolos 《International Journal of Coal Geology》2009,77(3-4):383-393

This study evaluates Greek peat and coal samples for applications in the agricultural/horticultural sector and assesses the suitability of a certain peat/coal either as soil conditioner or as raw material for manufacturing organic fertilizers.Twenty-six samples of different rank ranging from peat to subbituminous coal obtained from several Greek peat/coal deposits, were studied. The laboratory tests included: a) pH and electrical conductivity (EC) determinations, as well as proximate, ultimate and maceral analyses, in order to characterize the samples, b) major and trace element analyses of both the total and the easily exchangeable fractions (EEF), in order to assess the phytotoxicity effect, c) cation exchange capacity (CEC) determination in mixtures of the samples (5 wt.%) with a certain soil (95 wt.%), in order to evaluate the peat/coal impact, and d) the determination of the contents of humic substances (HS), as well as of carboxylic and phenolic groups.The majority of the samples reveal moderate to high ash yields (16–80 wt.%), a slightly acidic to neutral character and electrical conductivity ranging from 100–2500 μS/cm. Concerning the environmental impact of the sensitive trace elements, which might be leached, As, Mn, Ni and Sr show relatively strong mobilization in some samples, although severe impacts are not expected. The soil's CEC is generally improved, although it remains at moderate levels. The most interesting aspect is the humic acids content, which ranges between 9.6 and 52.2 wt.% on a dry basis, exceeding 25 wt.% for most of the samples. The obtained results enable an initial correlation among the different parameters and a rating of the samples according to their suitability for soil-amelioration agents.  相似文献   

Mediterranean forest mapping using hyper-spectral satellite imagery   总被引：2，自引：0，他引：2  

Selma Etteieb  Mounir Louhaichi  Chariton Kalaitzidis  Ioannis Z. Gitas 《Arabian Journal of Geosciences》2013,6(12):5017-5032

Mediterranean forests are characterized by spatiotemporal heterogeneity that is associated with Mediterranean climate, floristic biodiversity and topographic variability. Satellite remote sensing can be an effective tool for characterizing and monitoring forest vegetation distribution within these fragmented Mediterranean landscapes. The heterogeneity of Mediterranean vegetation, however, often exceeds the resolution typical of most satellite sensors. Hyper-spectral remote sensing technology demonstrates the capacity for accurate vegetation identification. The objective of this research is to determine to what extent forest types can be discriminated using different image analysis techniques and spectral band combinations of Hyperion satellite imagery. This research mapped forest types using a pixel-based Spectral Angle Mapper (SAM), nearest neighbour and membership function classifiers of the object-oriented classification. Hyperion classification was done after reducing Hyperion data using nine selected band combinations. Results indicate that the selection of band combination while reducing the Hyperion dataset improves classification results for both the overall and the individual forest type accuracy, in particular for the selected optimum Hyperion band combination. One shortcoming is that the performance of the best selected band combination was superior in terms of both overall and individual forest type accuracy when applying the membership classifier of the object-oriented method compared to SAM and nearest neighbour classifiers. However, all techniques seemed to suffer from a number of problems, such as spectral similarity among forest types, overall low energy response of the Hyperion sensor, Hyperion medium spatial resolution and spatiotemporal and spectral heterogeneity of the Mediterranean ecosystem at multiple scales.  相似文献   

Pounding of buildings in series during earthquakes     

Stavros A. Anagnostopoulos 《地震工程与结构动力学》1988,16(3):443-456

A simplified model of several adjacent buildings in a block is used to study the pounding of such buildings due to strong earthquakes. Considerable structural damage and even some collapses have sometimes been attributed to this effect. Each structure is modelled as a S.D.O.F. system and pounding is simulated using impact elements. A parametric investigation of this problem shows that the end structures experience almost always substantial increases in their response while for ‘interior’ structures the opposite often happens. This may explain why high percentages of corner buildings have collapsed in some earthquakes.  相似文献   

Web-based Data and Monitoring Platform for Complex Geotechnical Engineering Projects     

Frank Rackwitz  Stavros A. Savidis  Jens Rickriem 《Geotechnical and Geological Engineering》2013,31(3):927-939

Data management is the key of geotechnical risk management and disaster prevention providing right information at right time and right place. It supports regular construction cycles as well as handling of exceptional situations occurring probably during execution stages where the detailed knowledge of the actual state of construction is especially important. The web-based client–server software platform DoMaMoS was developed to cover all aspects in a new fashion. Main parts of the software are a graphical user interface, a SQL database and a controller application. Software development concerned user-friendly handling, geotechnical monitoring, security aspects, rapid access and adaptivity during a running project. Basic ideas and main features of the developed software are described and the practical application is shown.  相似文献   

The effect of seasonal and long-period geopotential variations on the GPS orbits     

Stavros A. Melachroinos  Frank G. Lemoine  Douglas S. Chinn  Nikita P. Zelensky  Joseph B. Nicholas  Brian D. Beckley 《GPS Solutions》2014,18(4):497-507

We examine the impact of using seasonal and long-period time-variable gravity field (TVG) models on GPS orbit determination, through simulations from 1994 to 2012. The models of time-variable gravity that we test include the GRGS release RL02 GRACE-derived 10-day gravity field models up to degree and order 20 (grgs20x20), a 4 × 4 series of weekly coefficients using GGM03S as a base derived from SLR and DORIS tracking to 11 satellites (tvg4x4), and a harmonic fit to the above 4 × 4 SLR–DORIS time series (goco2s_fit2). These detailed models are compared to GPS orbit simulations using a reference model (stdtvg) based on the International Earth Rotation Service (IERS) and International GNSS Service (IGS) repro1 standards. We find that the new TVG modeling produces significant along, cross-track orbit differences as well as annual, semi-annual, draconitic and long-period effects in the Helmert translation parameters (Tx, Ty, Tz) of the GPS orbits with magnitudes of several mm. We show that the simplistic TVG modeling approach used by all of the IGS Analysis Centers, which is based on the models provided by the IERS standards, becomes progressively less adequate following 2006 when compared to the seasonal and long-period TVG models.  相似文献   

Regional projections of the likelihood of very large wildland fires under a changing climate in the contiguous Western United States     

E. Natasha Stavros  John T. Abatzoglou  Donald McKenzie  Narasimhan K. Larkin 《Climatic change》2014,126(3-4):455-468

Seasonal changes in the climatic potential for very large wildfires (VLWF?≥?50,000 ac?~?20,234 ha) across the western contiguous United States are projected over the 21st century using generalized linear models and downscaled climate projections for two representative concentration pathways (RCPs). Significant (p?≤?0.05) increases in VLWF probability for climate of the mid-21st century (2031–2060) relative to contemporary climate are found, for both RCP 4.5 and 8.5. The largest differences are in the Eastern Great Basin, Northern Rockies, Pacific Northwest, Rocky Mountains, and Southwest. Changes in seasonality and frequency of VLWFs d7epend on changes in the future climate space. For example, flammability-limited areas such as the Pacific Northwest show that (with high model agreement) the frequency of weeks with VLWFs in a given year is 2–2.7 more likely. However, frequency of weeks with at least one VLWF in fuel-limited systems like the Western Great Basin is 1.3 times more likely (with low model agreement). Thus, areas where fire is directly associated with hot and dry climate, as opposed to experiencing lagged effects from previous years, experience more change in the likelihood of VLWF in future projections. The results provide a quantitative foundation for management to mitigate the effects of VLWFs.  相似文献   

Early coalification features as approached by solid state C CP/MAS NMR spectroscopy     

S. Kalaitzidis  K. Christanis  A. Iordanidis 《Geochimica et cosmochimica acta》2006,70(4):947-959

Solid state ¹³C CP/MAS NMR spectroscopy and ultimate analysis have been applied to a study of samples from the Pleistocene Drama lignite and its successive modern analogue, the Philippi peat, in northeastern Greece. The succession from peat to lignite resulted in a C enrichment averaging 10.7% and depletion in H and O averaging 6.5 and 18.5%, respectively. Early coalification resulted in the degradation of methoxyl groups, carbohydrates and carboxylic groups, whereas the aliphatic carbons were less affected. However, organic geochemical alteration seems to depend strongly on the initial peatification conditions. The “aromaticity” decreases from the stage of peat to lignite, as a result of the significant degradation of lignin precursors.  相似文献   

Soil–structure interaction in the time domain using halfspace Green's functions     

Christopher Bode  Reinhold Hirschauer  Stavros A. Savidis 《Soil Dynamics and Earthquake Engineering》2002,22(4)

A time-domain formulation is proposed for the transient response analysis of general, three-dimensional structures resting on a homogeneous, elastic halfspace subjected to either external loads or seismic motions. The formulation consists of two parts: (a) the time domain formulation of the soil behaviour and (b) the coupling of the corresponding soil algorithms to the Finite Element Code ANSYS. As far as the structure is concerned, this coupling opens the way for the analysis of non-linear soil–structure interaction. The approach is based on halfspace Green's functions for displacements elicited by Heaviside time-dependent surface point loads. Hence, the spatial discretisation can be confined to the contact area between the foundation and the soil, i.e. no auxiliary grid beyond the foundation as for conventional boundary element formulations is required. The method is applied to analyse the dynamic response of a railway track due to a moving wheel set by demonstrating the influence of ‘through-the-soil coupling’.  相似文献   

Evaluation of combination rules for maximum response calculation in multicomponent seismic analysis by O. A. López,A. K. Chopra and J. J. Hernández,Earthquake Engng Struct. Dyn. 2001; 30(9):1379–1398     

Stavros A. Anagnostopoulos 《地震工程与结构动力学》2002,31(9):1753-1754

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