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

The Sanandaj–Sirjan Zone in the Neo-Tethyan suture, western Iran: Zircon U–Pb evidence of late Palaeozoic rifting of northern Gondwana and mid-Jurassic orogenesis

The Zagros Orogen, marking the closure of the Neo-Tethyan Ocean, formed by continental collision beginning in the late Eocene to early Miocene. Collision was preceded by a complicated tectonic history involving Pan-African orogenesis, Late Palaeozoic rifting forming Neo-Tethys, followed by Mesozoic convergence on the ocean\u27s northern margin and ophiolite obduction on its southern margin. The Sanandaj-Sirjan Zone is a metamorphic belt in the Zagros Orogen of Gondwanan provenance. Zircon ages have established Pan-African basement igneous and metamorphic complexes in addition to uncommon late Palaeozoic plutons and abundant Jurassic plutonic rocks. We have determined zircon ages from units in the northwestern Sanandaj-Sirjan Zone (Golpaygan region). A sample of quartzite from the June Complex has detrital zircons with U-Pb ages mainly in 800-1050 Ma with a maximum depositional age of 547 ± 32 Ma (latest Neoproterozoic¿earliest Cambrian). A SHRIMP U-Pb zircon age of 336 ± 9 Ma from gabbro in the June Complex indicates a Carboniferous plutonic event that is also recorded in the far northwestern Sanandaj-Sirjan Zone. Together with the Permian Hasanrobat Granite near Golpaygan, they all are considered related to rifting marking formation of Neo-Tethys. Scarce detrital zircons from an extensive package of metasedimentary rocks (Hamadan Phyllite) have ages consistent with the Triassic to Early Jurassic age previously determined from fossils. These ages confirm that an orogenic episode affected the Sanandaj-Sirjan Zone in the Early to Middle Jurassic (Cimmerian Orogeny). Although the Cimmerian Orogeny in northern Iran reflects late Triassic to Jurassic collision of the Turan platform (southern Eurasia) and the Cimmerian microcontinent, we consider that in the Sanandaj-Sirjan Zone a tectonothermal event coeval with the Cimmerian Orogeny resulted from initiation of subduction and closure of rift basins along the northern margin of Neo-Tethys

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