Effectiveness of tune mass damper in the reduction of the seismic response of the structure     

Zoran T. Rakicevic  Aleksandra Bogdanovic  Dimitar Jurukovski  Peter Nawrotzki 《Bulletin of Earthquake Engineering》2012,10(3):1049-1073

A shaking table testing of a 16.6 t five storey steel frame structure with and tuned mass damper (TMD) named as Tuned Mass Control System (TMCS) installed at the top has been carried out in the Dynamic Testing Laboratory at the Institute of Earthquake Engineering and Engineering Seismology (IZIIS) in Skopje, Republic of Macedonia. For estimation of the effectiveness of Tuned Mass Control System (TMCS) large number of shaking table experiments have been performed. Simulating different earthquake time histories on the model structure with and without TMCS it has been demonstrated that this system is capable to reduce the responses in order from 10% to more than 50% depending on the frequency content of the seismic input and the corresponding sensitivity of the structure. Given a high quality analytical model of a structure and a dynamic absorber, a series of variant analyses have been performed within the study to investigate the effect of the individual parameters and evaluate the efficiency of the dynamic absorber. The analyses have been performed to define the effect of the location of the absorber, also, upon the dynamic behaviour of the structure in the case the absorber is installed at the different level (storey) of the structure. Comparative analysis of the structure with TMCS having optimally tuned its mechanical properties versus structure that has TMCS having the same mechanical properties as tested specimen showed that the TMCS additionally improves the structural behaviour, depending on frequency content of earthquake excitation.  相似文献   

Topocentric orbit determination: Algorithms for the next generation surveys     

Andrea Milani  Giovanni F. Gronchi  Zoran Kne?evi?  Larry Denneau 《Icarus》2008,195(1):474-492

The process of calculating a good orbit from astrometric observations of the same object involves three main steps: preliminary orbit determination, least squares orbit fitting, and quality control assessing the orbit's uncertainty and reliability. For the next generation sky surveys, with much larger number density of observations, new algorithms, or at least substantial revisions of the classical ones, are needed. The classical theory of preliminary orbit algorithms was incomplete in that the consequences of the topocentric correction had not been fully studied. We show that it is possible to rigorously account for topocentric observations and that this correction may increase the number of alternate preliminary orbits without impairing the overall performance. We have developed modified least squares algorithms including the capability of fitting the orbit to a reduced number of parameters. The restricted fitting techniques can be used to improve the reliability of the orbit computing procedure when the observed arcs have small curvature. False identification (where observations of different objects are incorrectly linked together) can be discarded with a quality control on the residuals and a ‘normalization’ procedure removing duplications and contradictions. We have tested our algorithms on two simulations based on the expected performance of Pan-STARRS—one of the next generation all-sky surveys. The results confirm that large sets of discoveries can be handled very efficiently resulting in good quality orbits. In these tests we lost only 0.6 to 1.3% of the possible objects, with a false identification rate in the range 0.02 to 0.06%.  相似文献   

Correlation Of Balkan Endemic Nephropathy With Fluorescent Organic Compounds In Shallow Groundwater     

Marvin C. Goldberg  Gerald L. Feder  Zoran Radovanovic 《Hydrogeology Journal》1994,2(4):15-22

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富有机质粘土环境、方解石环境和成煤环境中的黄铁矿成因     

Gordana DEVIC  Petar PFENDT  Branimir JOVANCICEVIC  Zoran POPOVIC 《地质学报》2006,80(8):1218

本文对赋存于中新统混杂沉积物中淡水序列(如粘土中的煤层夹矸,砂岩以及页岩)与连续的褐煤层相互交替的地层中的黄铁矿及黄铁矿形成过程中早期的成岩特征进行了研究。根据大量的矿物特征观察,黄铁矿形成的主要沉积环境为:伊利石-蒙脱石环境(I-M),方解石环境(Ct)和成煤环境。根据热液地球化学环境与黄铁矿二者的相互关系,本文对不同的热液地球化学环境对黄铁矿形成的影响因素进行了分析。由于影响因素的差异,特定环境下的黄铁矿形成过程具有较大的不同。根据所处环境的pH值以及粘土矿物的吸附性中不同的氧化活动性、铁离子的络合物以及腐殖…  相似文献   

Analytical modelling of wintertime coastal jets in the Adriatic Sea     

Martin Lazar  Marko Pavić  Zoran Pasarić  Mirko Orlić 《Continental Shelf Research》2007

Two diagnostic models, reproducing circulation generated in a marginal sea by variable density, have been developed. The models’ domain is a 2D transverse section for which analytical solutions have been obtained. They describe the winter situation in the northern Adriatic, with a strong vertical mixing present and the density maximum dominating the centre of the basin. Both models employ Boussinesq-type parametrisation of friction and linear slip at the bottom. The first model allows for frictional departure from hydrostatic equilibrium and includes vertical friction only. The second one is hydrostatic but allows for lateral friction as well. The results obtained by the two models are similar and to some extent dependent on the vertical and bottom friction. They reproduce several well known characteristics of the Adriatic circulation (cyclonic surface flow, downwelling in the central and larger part of the basin compensated by upwelling in the coastal zone) but also predict some phenomena that are still not well understood. A conspicuous feature of the model results are coastal jets, which were observed in the Adriatic on several occasions. The present models show that the distance of jets from the coasts depends on lateral friction: it is found to vary from 1 up to 10 km on the Italian side and between 2 and 15 km on the Croatian side. Both models reproduce the west–east asymmetry, with the wider current on the east side of the basin. The asymmetry is a subject on which conflicting empirical results exist in the Adriatic. In the two models cyclonic flow occupies the whole water column, which disagrees with some recent theoretical findings of the near-bottom anticyclonic flow and thus leaves the issue open.  相似文献   

A post-IR IRSL chronology and dust mass accumulation rates of the Nosak loess-palaeosol sequence in northeastern Serbia     

Zoran M. Perić  Slobodan B. Marković  György Sipos  Milivoj B. Gavrilov  Christine Thiel  Christian Zeeden  Andrew S. Murray 《Boreas: An International Journal of Quaternary Research》2020,49(4):841-857

In the Middle Danube Basin, Quaternary deposits are widely distributed in the Vojvodina region where they cover about 95% of the area. Major research during the last two decades has been focused on loess deposits in the Vojvodina region. During this period, loess in the Vojvodina region has become one of the most important Pleistocene European continental climatic and environmental records. Here we present the dating results of 15 samples taken from the Nosak loess-palaeosol sequence in northeastern Serbia in order to establish a chronology over the last three glacial–interglacial cycles. We use the pIRIR₂₉₀ signal of the 4–11 μm polymineral grains. The calculated ages are within the error limits partially consistent with the proposed multi-millennial chronostratigraphy for Serbian loess. The average mass accumulation rate for the last three glacial–interglacial cycles is 265 g m⁻² a⁻¹, which is in agreement with the values of most sites in the Carpathian Basin. Our results indicate a highly variable deposition rate of loess, especially during the MIS 3 and MIS 6 stages, which is contrary to most studies conducted in Serbia where linear sedimentation rates were assumed.  相似文献   

Discriminant function model as a tool for classification of stratigraphically undefined radiolarian cherts in ophiolite zones     

Zoran Peh  Josip Halamić 《Journal of Geochemical Exploration》2010

Two discriminant function models are constructed in order to distinguish major- and trace-element geochemical patterns characteristic for radiolarian cherts from the Zagorje–Mid-Transdanubian Zone ophiolite mélange of NW Croatia. The models are subsequently used to assign new samples from the adjacent magmatic–sedimentary complex extending from the Central Dinaridic Ophiolite Belt in NW Bosnia and thereby to test their applicability in similar cases when clear field relations are absent. In both models the first discriminant function explains the most part of the system variability. However, between the two, the trace-element model proves itself as a more helpful predictive tool presenting a straightforward example of correct classification of samples into three pre-defined groups (Triassic-basin, Triassic-slope and Jurassic radiolarian cherts). This result is extended further, with allocation of all samples from the test region into a single group (Jurassic) according to their trace-element geochemistry.  相似文献   

Canonical correlation analysis as a tool in the provenance study of overbank sediments from the small mountainous watersheds     

Zoran Peh  Marta Mileusnić  Slobodan Miko 《Environmental Earth Sciences》2011,64(4):1139-1155

Canonical correlation analysis (CCA) is used in this study in order to trace the lineage of overbank sediment from the initial erosion of the parent rocks down to deposition of detrital material in alluvium of the small mountainous watersheds of the Žumberak area, Croatia. It helps to elucidate relations between the hierarchically structured systems (rocks, minerals, elements) represented by the ensembles of lithological, mineralogical and geochemical variables. Taking their place in the vertical order of hierarchical complexity, geochemistry and mineralogy of the recent material are considered dependent variable regarding the related watershed lithology, with geochemical variables (major and trace elements) last in the chain. Three canonical models are built and cross-compared in order to unravel the between-level relationships and infer the basic patterns of mineral and geochemical flux from the source rocks to basin. From these, the two hierarchical (provenance) chains epitomized in recombination of the first two canonical functions have been derived highlighting complementary provenances, weathering styles, and dispersion avenues in alluvial sedimentation of the study area. The first clearly separates carbonate from siliciclastic sedimentary source while the second illuminates the origin of phyllosilicate and ferric oxyhydroxide phases with associated suite of elements in absence of clear carbonate signal.  相似文献   

Changes in beach gravel lithology caused by anthropogenic activities along the southern coast of Lake Michigan, USA     

Zoran Kilibarda  Nolan Graves  Melissa Dorton  Richard Dorton 《Environmental Earth Sciences》2014,71(3):1249-1266

The southern coast of Lake Michigan is the most urbanized and most densely populated area in the Great Lakes region. Development of steel mills, harbors, and municipalities in NW Indiana and in NE Illinois in the last century and a half altered the nearshore environment so much that native beach gravel (>8 mm) now exist only in the exhumed paleo-beach remnants from the Nipissing Phase (~4,500 years ago) of Lake Michigan. Native gravel, collected from paleo-beach remnants at Mount Baldy Dune and Beach House Blowout, contain predominantly beach shingle, very platy siltstones (71–78 %), with secondary crystalline pebbles (18 %) in the east, and carbonate pebbles (12 %) in the west. A large amount of anthropogenic fill (steel industry waste, waste from power generating plants, construction debris, railroad, and road fill) has been added since the late 1800s to fill Lake Michigan and expand industrial land. Four areas of major coastal structures—Michigan City Pier and Breakwater, Burns Harbor Pier and Breakwater, Gary Works Pier, and Indiana Harbor Peninsula—altered the natural littoral drift and created four independent sectors on Indiana’s coast—Northeastern, Eastern, Central, and Western—between which no natural transfers of coarse sediments occur. Downdrift from the coastal structures, severe beach erosion has prompted extensive beach nourishment with non-native sandy gravel. Four distinct populations of modern beach gravel now exist along Indiana’s coast of Lake Michigan: (1) native gravel with diluted beach nourishment influence, (2) native gravel with a minor industrial influence, (3) compact gravel of nourished origin, and (4) anthropogenic gravel of industrial origin. Native gravel with diluted nourishment influence is found in the western, downdrift areas of the Northeastern (from Long Beach to Washington Park Beach) and Eastern Sectors (from eastern Indiana Dunes State Park to western Dune Acres) and contains up to 40 % compact carbonate and crystalline pebbles in addition to native beach shingle. Native gravel with minor industrial influence is found in the Central Sector of Indiana’s coast (from central Ogden Dunes to Marquette Beach) and contains predominantly beach shingle, platy clastic lithology, but also up to 30 % of chert and other pebbles released by industry. Compact gravel of nourished origin contains 60–90 % of carbonate and crystalline pebbles, and is found in the eastern, updrift areas of the Northeastern (Michiana Beach and Duneland Beach) and Eastern Sectors (from Crescent Beach to the western Beverly Shores). Anthropogenic gravel of industrial origin contains 70–90 % compact chert and slag and is found in every beach of the Western Sector and in the westernmost beach of the Central Sector. Streams draining into southern Lake Michigan generally contain little coarse sediment except in their channels near the roads and railroads, where angular to subangular anthropogenic pebbles predominate (70–90 %). However, streams have very little influence on gravel lithology along the coast because they seldom discharge anthropogenic gravel into Lake Michigan. Recent changes in gravel lithology along the southern Lake Michigan coast may affect changes in nearshore benthic flora and fauna as well as algal and bacterial blooms during warm summer months.  相似文献   

Surveillance of Vrancea active seismic region in Romania through time series satellite data     

Maria A. Zoran  Roxana S. Savastru  Dan M. Savastru 《Central European Journal of Geosciences》2014,6(2):195-206

Cumulative stress energy in active seismic regions caused by tectonic forces creates various earthquake precursors. This energy transformation may result in enhanced transient thermal infrared (TIR) emission, which can be detected through satellites equipped with thermal sensors like MODIS (Terra/Aqua) and AVHRR (NOAA). Satellite time-series data, coupled with ground based observations, where available, can enable scientists to survey pre-earthquake signals in the areas of strong tectonic activity. This paper presents observations made using time series MODIS and NOAA-AVHRR satellite data for derived multi-parameters including land surface temperature (LST), outgoing long-wave radiation (OLR), and mean air temperature (AT) for the moderate, 5.9 magnitude earthquake, which took place on the 27^th of October, 2004, inthe seismic region of Vrancea, in Romania. Anomalous thermal infrared signals, reflected by a rise of several degrees celsius (°C) in LSTs, and higher OLR values were seen several days before the earthquake. AT values in the epicentral area also increased almost two days prior to the earthquake and intensified three days after the main shock. Increases in LSTs and OLR disappeared three days after the main shock. The survey and joint analysis of geospatial and in-situ geophysical information on land surface temperatures and outgoing long-wave radiation provides new insights into the field of seismic hazard assessment in Vrancea, a significant area of tectonic activity in Romania and Europe.  相似文献