The results of the detailed seismoacoustic profilling (CSP, boomar) are presented. The investigation has been carried out in February 1985 and 1988 during two Geodynamical Expeditions organized by the Institute of Geophysics of the Polish Academy of Sciences. The boomar penetration of the caldera floor went down to 150 msec. Four seismoacoustic units of volcanic formations have been determined. The unit A corresponds to pre-caldera series and occurred only in the border part of the flooded caldera. The unit contains mainly pyroclastic rocks (consolidated agglomerates and tuffs) and probably some intercalations of lavas. The units B, C and D fill up the caldera bottom and correspond to post-caldera series. The units are composed of pyroclastic rocks, containing also materials redeposited by lahars, glaciers, landwaters and by wind. The units C and D (the youngest one) were certainly deposited under water. All the units are cut by numerous faults, vents and other types of intrusions. The larger faults, en echelon type, are situated around the bottom and form a ring-fracture. Caldera was formed by succesive stages of collapsing. This process is not finished yet and volcanic activity is still alive (especially in the western part of the flooded caldera).
On the ground of results obtained by the seismoacoustic profiling carried out in 1985 and primary examination of core samples the following main seismoacoustic units are distinguished and characterized: unit A — bedrock, unit B — till and/or compacted glaciomarine deposit, unit C — glaciomarine ice-front deposit, unit D — glaciomarine mud. These results enabled to present the distribution of seismoacoustic units along the fiord and its extension on the shelf, as well as to determine a relation of bottom structures to Late Vistulian(?) deglaciation and the action of Holocene tributary glaciers, probably during the Little Ice Age. The position of marginal structures corresponding to local retreat stages of the glacier front is also presented.
A sea floor investigation was performed in the fiord of Hornsund by means of the seismoacoustic profiling, echosounding and core sampling. The main seismoacoustic sea floor units were recognized (the methods used according to Kowalewski et al. 1987a) and characterized on the basis of their relations to geomorphology and geological evolution. The bathymetrical sketch and the resulting geomorphological description of the bottom were prepared. The surface of the sea bottom and the surface of the bedrock displayed an irregular high relief with large sills dividing the fiord sea floor into several basins. Four main types of the sills were distinguished: burried sills, accumulative sills, rock sills and rock-accumulative sills. Within the internal Basins I and II there were thick (up to 170 m) covers of the glaciomarine ice-front deposit with changing thin ( 1 -5 m) blanket of the glaciomarine muds at the bottom surface. The Basin III had a cover of the glacial and glaciomarine deposits of variable lithology, genesis and age. The most external Basin IV had a cover o f glaciomarine muds up to 4 0 - 5 0 m thick, deposited on the tills. Four main glacial episodes were recognized, most probably referring to the stadials of Lisbetdalen, Slaklidalen, Revdalen and to the Little Ice Age.
Abstract Various optimization problems for linear parabolic systems with multiple constant time delays are considered. In this paper, we consider an optimal distributed control problem for a linear parabolic system in which multiple constant time delays appear in the Neumann boundary condition. Sufficient conditions for the existence of a unique solution of the parabolic equation with the Neumann boundary condition involving multiple time delays are proved. The time horizon T is fixed. Making use of the Lions scheme , necessary and sufficient conditions of optimality for the Neumann problem with the quadratic cost function with pointwise observation of the state and constrained control are derived.
Abstract Various optimization problems for linear parabolic systems with multiple constant time lags are considered. In this paper, we consider an optimal distributed control problem for a linear complex parabolic system in which different multiple constant time lags appear both in the state equation and in the Neumann boundary condition. Sufficient conditions for the existence of a unique solution of the parabolic time lag equation with the Neumann boundary condition are proved. The time horizon T is fixed. Making use of the Lions scheme , necessary and sufficient conditions of optimality for the Neumann problem with the quadratic performance functional with pointwise observation of the state and constrained control are derived. The example of application is also provided.
Artykuł rozpoczyna się od rekonstrukcji dyskursu o kryzysie demokracji i reakcji wywoływanych przez ten rodzaj narracji. Następnie omówiono ideę protestu miejskiego, wskazując na dwoiste oblicze obywateli miasta i ambiwalentne reakcje miast na zjawisko dekapilaryzacji władzy. Aby ukazać złożoność i różnorodność opisywanego zagadnienia, autor przywołuje przykłady miejskiego populizmu i reakcji na to zjawisko (między innymi w miastach Polski, Kanady, Włoch, Holandii, Niemiec). Autor w tekście wskazuje, że odpowiedź miast na populizm i kryzys demokracji wzmacnia lub osłabia tendencje autorytarne, zarówno w przypadku działań instytucjonalnych (związanych z tworzeniem i realizacją lokalnej polityki), jak i pozainstytucjonalnych (związanych ze sferą aktywizmu mieszkańców).
The paper presents results of investigations of bottom sediments in Hornsund, Wijdefjorden and Isfjorden as well as of the shelf around the Bjornoya. carried out in 1982—1985 by a continuous seismic profiling. Geophysic structures and bottom sediments on the bedrock to a depth of 170 ms have been recognized, particularly in the Hornsund region. The following seismoacoustic units have been distinguished: unit A — bedrock, unit В — till and/or compacted glaciogenic deposit, unit С — glaciomarine ice-front deposit, unit D — glaciomarine mud. These results allowed to present a model of glaciomarine sedimentation in a fiord, fed by warm tidewater glaciers.
A new method of noise generation based on software implementation of a 7-bit LFSR based on a common polynomial PRBS7 using microcontrollers equipped with internal ADCs and DACs and a microcontroller noise generator structure are proposed in the paper. Two software applications implementing the method: written in ANSI C and based on the LUT technique and written in AVR Assembler are also proposed. In the method the ADC results are used to reseed the LFSR after its each full work cycle, what improves randomness of generated data, which results in a greater similarity of the generated random signal to white noise, what was confirmed by the results of experimental research. The noise generator uses only the internal devices of the microcontroller, hence the proposed solution does not introduce hardware redundancy to the system.
This paper is concerned with the determination of the auditory filter shape using the notched noise method with noise bands symmetrically located above and below a probe frequency of 10 kHz. Unlike in the classical experiments conducted with the use of Patterson method the levels as well as power spectrum densities of the lower and upper component bands of the notched noise masker were not the same and were set such as to produce the same amount of masking at the 10-kHz frequency. The experiment consisted of three conditions in which the following values were determined: (I) the detection threshold for a 10-kHz probe tone in the presence of a noise masker presented below the tone’s frequency; (II) the level of a noise masker presented above the 10-kHz probe tone frequency, at which the masker just masked the probe tone, (III) the detection threshold for a probe tone in the presence of a notched-noise masker. The data show a considerable amount of variability across the subjects, however, the resulting frequency characteristics of the auditory filters are consistent with those presented in the literature so that the Equivalent Rectangular Bandwidth is less than 11% of their centre frequency.
In this paper the method of fast impedance spectroscopy of technical objects with high impedance (|Zx| ≥1 GΩ) is evaluated by means of simulation and a practical experiment. The method is based on excitation of an object with a sinc signal and sampling the response signals proportional to current flowing through and voltage across the measured impedance. The object’s impedance spectrum is obtained with the use of continuous Fourier transform on the basis of linear approximations between samples in two acquisition sections, connected with the duration of the sinc signal. The method is first evaluated in MATLAB by means of simulation. An influence of the sinc signal duration and the number of samples on impedance modulus and argument measurement errors is explored. The method is then practically verified in a constructed laboratory impedance spectroscopy measurement system. The obtained acceleration of impedance spectroscopy in the low frequency range (below 1 Hz) and the decrease of the number of acquired samples enable to recommend the worked out method for implementation in portable impedance analyzers destined for operation in the field.