An identification of the responsible faults for the destructive earthquakes of 1894 in the Atalanti region was carried out by employing a novel application of 3D finite-difference wavefield modeling. Several faults proposed in the literature were tested in detailed 3D simulations, by also utilizing a detailed local 3D velocity model, as well as the local topography. The assessment of the most probable sources for these events was based on the correlation of reported damages with the distribution of the simulated peak ground acceleration. Furthermore, the distribution of the spectral amplitudes at higher frequencies that are related to the resonant frequencies of the local buildings on that time period was also used as an indicator. The general effect of the local 3D subsurface structure on the propagation of the wavefield and the spatial distribution of the ground motion was also investigated. The Malessina fault was identified as a probable source for the main event of 20/4/1894 based on the results of the 3D modeling, whereas the 3D effect was found to be a highly contributing factor to the distribution of the simulated ground motion., Mouzakiotis Evangelos, Karastathis Vassilios, Voulgaris Nikolaos,Papadimitriou Panagiotis, Sboras Sotirios and Gerolymatos Ilias., and Obsahuje bibliografii
The paper presents the results of monitoring study undertaken during the period 2008 - 2010. The study recorded the displacement of tectonic structures in the Strašín Cave (SW Bohemian Massif). The derived results were compared, among others, with data recorded over the same time period across the Bohemian Massif in the EUTecNet (tectonic displacement monitoring net - see www.tecnet.cz), which is managed by IRSM ASCR. The rate of recorded displacement is mostly in order of hundredths mm/year with maximal value recorded in vertical component at site Strašín 2, about 0,16 mm/2,5 years. Whilst recorded displacement can indicate blocks subsidence into the cave empty space, the periods when displacement occurred correspond to periods of increased movement activity recorded for example at the opposite side of the Bohemian Massif, along the Sudetic Marginal Fault. Moreover, both periods are simultaneous with extraordinary earthquakes that affected western and southern part of the Bohemian Massif in 2008 and 2009., Josef Stemberk and Filip Hartvich., and Obsahuje bibliografii
Fault tolerant control for uncertain systems with time varying state-delay is studied in this paper. Based on sliding mode controller design, a fault tolerant control method is proposed. By means of the feasibility of some linear matrix inequalities (LMIs), delay dependent sufficient condition is derived for the existence of a linear sliding surface which guarantees quadratic stability of the reduced-order equivalent system restricted to the sliding surface. A reaching motion controller, which can be seen as a fault tolerant controller, can retain the stability of the closed loop system in the present of uncertainties, disturbances and actuator fault is designed. A numerical simulation shows the effectiveness of the approach.
Combat planes are designed in a structured relaxed static stability to meet maneuver requirements. These planes are unstable in the longitudinal axis and require continuous active control systems with elevator control. Therefore, failures in the elevator can have vital consequences for flight safety. In this work, the performance of classical control approach against asymmetric elevator failures is investigated and it is shown that this approach is insufficient in the case of such a failure. Then, a fault-tolerant control system is proposed to cope with these failures and it is shown that this controller can successfully deal with such failures. The F-16 aircraft is taken as an example case. A detailed nonlinear dynamic model of this aircraft is presented first. In the F-16 aircraft, the elevator surfaces are in two parts, right and left, and can move independently. Therefore, to obtain a more realistic and difficult failure scenario, it is assumed that the elevator is asymmetrically defective. Two types of failures commonly observed on the elevator surfaces (freezing and floating) are aerodynamically modeled and it is shown that the pitch-rate control augmentation systems in the conventional structure cannot cope with these elevator failures. In order to overcome this problem, a fault-tolerant control system is proposed. It is shown that this controller can successfully cope with the aforementioned failures without any degradation in flight safety.
It is widely assumed that the possibility of faultless disagreement is to be explained by the peculiar semantics and/or pragmatics of special kinds of linguistic construction. For instance, if A asserts “o is F” and B asserts this sentence’s denial, A and B can disagree faultlessly only if they employ the right kind of predicate as their “F”. In this paper, I present an argument against this assumption. Focusing on the special case when the expression of interest is a predicate, I present a series of examples in which the same pairs of sentences are employed, but in different contexts. In some cases, we get an impression of faultless disagreement and in some cases we don’t. I identify a pattern across these contexts and conclude that faultless disagreement is made possible, not by a special kind of predicate, but instead by a special kind of context.
This article deal with phase diagnostics of femtosecond laser pulses and with its change to increase a nonlinear optical signal. We introduce a single shot technique of complex diagnostics SPIDER, which works on the base of interference in spectral region. Phase characteristics of investigated fs pulses incoming from oscillator was controlled by a prism pair. There was shown that phase characteristics changes of fs pulses leads to intensity changes of two photon fluorescence of coumarine C522 in ethanol.
Thanks to the development of fiber optic technologies for the Internet, large cities and metropolitan networks are now well connected through the fiber optic technology. Since the mid-nineties of the last century a rapid research in the transmission of stable frequencies via optical fibers has been introduced. It is necessary for mutual remote comparison of optical frequency standards via optical fibers. But in order to transmitting optical frequencies through photonic data networks, the key task is to compensate the Doppler shift that is induced in the fibers by external influences, such as particularly changes in the temperature or acoustic noise and mechanical vibration environment in which the fibers are installed. In this work we present some techniques to compensate these unwanted effects. Furthermore, we present the realization of an optical system and measurement parameters achieved by the phase-coherent optical transmission of the optical frequency standard working at a wavelength of 1540.5 nm. The optical frequency dissemination with the stable transport delay has been established on the fiber optic link leading from the Institute of Scientific Instruments ASCR Brno to headquarters of national provider CESNET in Prague over the optical fiber with the length of 306 km. The work includes the verification and measurement of changes of the transport delays using simultaneous bidirectional transmission of 1PPS signals from the instrument based atomic clocks placed in both ends of the same optical fiber. and Díky rozvoji komunikačních technologií pro internet jsou nyní dobře propojena velká města i metropolitní sítě optickými vlákny, čímž lze zajistit čistě fotonický přenos signálů na vzdálenosti až stovek kilometrů. Od poloviny devadesátých let minulého století probíhá intenzivní výzkum v oblasti přenosu stabilních frekvencí pomocí optických vláken, který je nezbytný pro vzájemná dálková porovnávání normálů optické frekvence. Aby však bylo možné přenášet optické frekvence přes běžné fotonické datové sítě, je nezbytné kompenzovat dopplerovský posuv, který je ve vláknech indukován působením vnějších vlivů, jako jsou zejména změny teploty či akustické a mechanické vibrace prostředí, ve kterém jsou vlákna uložena. V práci představujeme vybrané techniky kompenzace těchto nežádoucích efektů. Dále prezentujeme vlastní realizaci optické soustavy a měření dosažených parametrů fázově koherentního přenosu optické frekvence normálového laseru pracujícího na vlnové délce 1540,5 nm z pracoviště Ústavu přístrojové techniky AV ČR v Brně do ústředí poskytovatele fotonických služeb CESNET v Praze po optickém vlákně délky 306 km. Součástí výsledků je i verifikace měření změn dopravního zpoždění pomocí obousměrného simultánního přenosu signálů 1PPS z přístrojových atomových hodin umístěných v obou lokalitách po stejném optickém vlákně.
In recent modernized era, the number of the Facebook users is increasing dramatically. Moreover, the daily life information on social networking sites is changing energetically over web. Teenagers and university students are the major users for the different social networks all over the world. In order to maintain rapid user satisfactions, information flow and clustering are essential. However, these tasks are very challenging due to the excessive datasets. In this context, cleaning the original data is significant. Thus, in the current work the Fishers Discrimination Criterion (FDC) is applied to clean the raw datasets. The FDC separates the datasets for superior fit under least square sense. It arranges datasets by combining linearly with greater ratios of between -- groups and within the groups. In the proposed approach, the separated data are handled by the Bigtable mapping that is constructed with Map specification, tabular representation and aggregation. The first phase organizes the cleaned datasets in row, column and timestamps. In the tabular representation, Sorted String Table (SSTable) ensures the exact mapping. Aggregation phase is employed to find out the similarity among the extracted datasets. Mapping, preprocessing and aggregation help to monitor information flow and communication over Facebook. For smooth and continuous monitoring, the Dynamic Source Monitoring (DSM) scheme is applied. Adequate experimental comparisons and synthesis are performed with mapping the Facebook datasets. The results prove the efficiency of the proposed machine learning approaches for the Facebook datasets monitoring.
The effect of tonsillectomy on production of Czech vowels /a/ and /i/ is numerically examined. Similar experimental studies are difficult to realise on living subjects. Finite element (FE) models of the acoustic spaces corresponding to the human vocal tract for the Czech vowels /a/ and /i/ with acoustic space around the human head are used in numerical simulations of phonation. The acoustic resonant characteristics of the FE models are studied by modal and transient analyses. The production of vowels is simulated in time-domain using transient analysis of FE models excited at the position of vocal folds by analytically desctibed Liljencrants-Fant‘s (LF) glottal signal model. The results show that tonsillectomy causes frequency shifts of some formant frequencies up to 150 Hz. The frequency shift of formants significantly depends on position and size of the tonsils. and Obsahuje seznam literatury