Оценка помехоустойчивости многочастотных систем связи при воздействии импульсного шума

Impact of impulsive noise on performance of uncoded and coded OFDM system is considered with account for the fact that the length of modulation symbol can be com.parable with average length of noise pulses. Temporal dynamics of noise is described by a Markov model. Theoretical calculations and simulation results lead to the following conclusions: efficient averaging of noise level takes place if average duration of noise pulses does not exceed 1% of OFDM symbol length; during the noise burst power losses due to impulsive nature of noise can reach 2…2,5 dB. Multi-frequency com.munication system, impulse noise, data transmission over the power line.Рассмотрено влияние импульсного шума на некодированные и кодированные многочастотные (OFDM) системы с учетом того, что длительность символа может быть сопоставима со средней длительностью импульса шума. Временна́я динамика возникновения импульсов шума описана марковской моделью. Теоретические расчеты и результаты моделирования позволяют заключить, что эффективное усреднение уровня шума происходит, если средняя длительность его импульсов не превосходит 1 % от длительности OFDM-символов. Во время действия пачки импульсов энергетические потери, обусловленные импульсным характером шума, могут достигать 2…2,5 дБ

Late Permian palaeomagnetic data east and west of the Urals

We studied Upper Permian redbeds from two areas, one between the Urals and the Volga River in the southeastern part of Baltica and the other in north Kazakhstan within the Ural-Mongol belt, which are about 900 km apart; a limited collection of Lower-Middle Triassic volcanics from north Kazakhstan was also studied. A high-temperature component that shows rectilinear decay to the origin was isolated from most samples of all three collections. For the Late Permian of north Kazakhstan, the area-mean direction of this component is D = 224.3°, I =−56.8°, k = 161, Α 95 = 2.7°, N = 18 sites, palaeopole at 53.4°N, 161.3°E; the fold test is positive. The Triassic result ( D = 55.9°, I =+69.1°, k = 208, Α 95 = 4.2°, N = 7 sites, pole at 57.0°N, 134.1°E) is confirmed by a positive reversal test. The corresponding palaeomagnetic poles from north Kazakhstan show good agreement with the APWP for Baltica, thus indicating no substantial motion between the two areas that are separated by the Urals. Our new mean Late Permian direction for SE Baltica ( D = 42.2°, I = 39.2°, k = 94, Α 95 = 3.5°, N = 17 sites; palaeopole at 45.6°N, 170.2°E) is confirmed as near-primary by a positive tilt test and the presence of dual-polarity directions. The corresponding pole also falls on the APWP of Baltica, but is far-sided with respect to the coeval reference poles, as the observed mean inclination is shallower than expected by 13°± 4°. In principle, lower-than-expected inclinations may be attributed to one or more of the following causes: relative tectonic displacements, quadrupole and octupole terms in the geomagnetic field, higher-order harmonics (incl. secular variation) of the same field, random scatter, non-removed overprints, or inclination error during remanence acquisition and/or diagenetic compaction. Our analysis shows that most mechanisms from the above list cannot explain the observed pattern, leaving as the most likely option that it must be accounted for by inclination shallowing. Comparison with selected coeval results from eastern Baltica (all within Russia) shows that all of them are biased in the same way. This implies that they cannot be used for analysis of geomagnetic field characteristics, such as non-dipole contributions, without a more adequate knowledge of the required correction for inclination shallowing.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71899/1/j.1365-246X.2008.03727.x.pd

TURKIC-TYPE OROGENY AND ITS ROLE IN THE MAKING OF THE CONTINENTAL CRUST

▪ Abstract  Turkic-type orogeny is a class of collisional mountain building, in which the precollision history of one, or both, of the colliding continents involves the growth of very large, subcontinent-size subduction-accretion complexes, into which magmatic arc axes commonly migrate and thus enlarge the continent to which they are attached. A review of the evolution of two Phanerozoic (Altaids, Nipponides), one Neoproterozoic (East African), and one Archean (Yilgarn) Turkic-type orogens shows that this type of orogeny may have been the principal builder of the continental crust through recorded Earth history. The total juvenile material added to Turkic-type orogens at any one time in the Phanerozoic seems close to 1 km3/year, which about equals the amount of material annually fed into the mantle at subduction zones. As some 0.02 to 0.03% of that material is generally agreed to return to the crust by arc magmatism, these figures provide a minimum net growth rate for the continental crust during the Phanerozoic. </jats:p

Origin of the metamorphic flysch sequence of the Strandja Massif (NW Turkey) in the Tethyan Realm: insights from new age and structural data&amp;#160;

&amp;lt;p&amp;gt;The Strandja Massif is a key location for understanding the Paleozoic and Mesozoic tectonic evolution of the Tethyan Realm in the NW Turkey. Some researchers have suggested that the Strandja Massif is a part of the Cimmerian continent, but others consider it as a section of the southern passive continental margin of the Eurasia. Traditionally the massif is divided into two tectono-stratigraphic units: 1) Pre-Permian crystalline basement and 2) Mesozoic sedimentary cover. However, the ages of the lithostratigraphic units have been significantly revised following the recent geochronological studies. Structural relations between these units are not simple and should be re-examined carefully. Our previous studies have shown that the crystallization time of the magmatic rocks and sedimentation ages of the rocks range from late Proterozoic to Permian especially at the east of the Strandja Massif. In this study, the Serves metagreywacke sporadically containing metabasic rocks and Kumlukoy quartz-rich metasandstones are investigated at the north of the K&amp;amp;#305;y&amp;amp;#305;k&amp;amp;#246;y town, in order to check the first studies that assigned them to the Jurassic and Cretaceous cover deposits. These units stretch along the Black Sea coast and reveal significant differences with units that are exposed to the south. Particularly the Serves unit consists of alternation of lithic metasandstones, schists, and phyllites whereas metaconglomerate layers, marble and dolomite bodies are common among Jurassic rocks exposed in the south. Detrital zircon studies carried on the metasandstone reveal that the sedimentation should be younger than Visean-Serpukhovian, because the youngest U-Pb zircon age population obtained are between ~338 and 327 Ma. Considering widespread late Carboniferous magmatism (~312-306 Ma) in the Strandja Massif and bereft of such magmatics constrain deposition of this unit between ~327 and 312 Ma (early-middle Pennsylvanian). In contrast, the Kumlukoy Unit has quartz-rich metasandstones and it has lower metamorphic degree than the Serves Unit. The detrital zircons of these metasandstones, which were considered as Cretaceous in the previous studies, indicate that the sedimentation interval of the unit is younger than latest Permian (~256 Ma). According to the detrital ages obtained the Kumlukoy metasandstone represent a higher stratigraphical position than the Serves metagreywacke. The Kumlukoy metasandstone is most probably the equivalent of the Triassic metaclastics reported in the cover units of the NW Strandja Massif. Whereas the age and petrography of the Serves metagraywacke are similar to the Mahya Complex and Yavuzdere Arc which was interpreted as a paired magmatic arc-accretionary prism unit. Another interpretation is that the Serves Unit predates the Mahya Complex and Yavuzdere Arc and all of them represents a long-lasting subduction and accompanying accretion events in the late Paleozoic history of the Strandja Massif, namely the Silk-road Arc.&amp;lt;/p&amp;gt;</jats:p

Estimation of noise stability of multi-frequency com.munication systems when pulse noise impacting

Impact of impulsive noise on performance of uncoded and coded OFDM system is considered with account for the fact that the length of modulation symbol can be com.parable with average length of noise pulses. Temporal dynamics of noise is described by a Markov model. Theoretical calculations and simulation results lead to the following conclusions: efficient averaging of noise level takes place if average duration of noise pulses does not exceed 1% of OFDM symbol length; during the noise burst power losses due to impulsive nature of noise can reach 2…2,5 dB. Multi-frequency com.munication system, impulse noise, data transmission over the power line

Precambrian to Early Cretaceous rocks of the Strandja Massif (NW Turkey); evolution of a long lasting magmatic arc

The Strandja Massif, Turkey, forms a link between the Balkan Zone of Bulgaria, which is correlated with Variscan orogen in Europe, and the Pontides, where Cimmerian structures are prominent. Five fault-bounded tectonic units form the massif structure; 1) The Kırklareli Unit consist of the Paleozoic basement intruded by the Carboniferous to Triassic Kırklareli metagranites. It is unconformably overlain by Permian and Triassic metasediments. 2) The Vize Unite is made of the Neoproterozoic metasediments, Cambrian metagranites, and pre-Ordovician molasse. Unconformable Ordovician quartzites pass upward into quartz schists and then to marble and chert. Rocks of the Vize Unit are intruded by the late Carboniferous metagranites. 3) The Mahya accretionary complex and 4) the paired Yavuzdere magmatic arc were formed in the Carboniferous. 5) A nappe consisting of the Jurassic dolomites and marbles thrust to the north in late Jurassic – early cretaceous time. This thrusting affects all above-mentioned tectonic units. Tectonic subdivision of the Strandja Massive is supported by 19 newly obtained age determinations of magmatic and detrital zircons. The LA ICPMS and SHRIMP U–Pb methods of isotopic dating have been used in this study. The long duration of magmatism in the reign and its continuity in the Triassic contradicts to the widely accepted ideas about the dominance of the passive continental margin settings in the tectonic evolution. The Strandja Massif is interpreted as a fragment of the long-lived, Cambrian to Triassic Silk Road magmatic arc. At least since the late Paleozoic this arc evolved on the northern side of Paleo-Tethys.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author