Wyniki wyszukiwania - Biblioteka Nauki

1

The role of gas bubbles in the acoustical oceanography

100%

Klusek Z.

Hydroacoustics

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2000

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tom Vol. 3

91--98

EN

The paper below presents different aspects of influence of subsurface bubble population on acoustical environment. The role of bubbles in ambient sea noise emission, reverberation processes and signals transmission is presented. The attention has been devoted to specific properties of the Baltic Sea water and its influence on bubble population.

2

Scanning tunneling spectroscopy of the NaDDP molecules deposited on the (0001) graphite surface in the presence of charging effects

100%

Klusek Z.

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2000

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tom Vol. 33, No. 3

344-349

EN

By the use STM/STS methods we have observed the growth of the NaDDP molecules on the pure and thermally rtched graphite substrate from solution. The deposition process leads to the appearance of a well-defined three-dimensional and two-dimensional molecular crystals on the graphite surface. TheSTS measurements on the two-dimensional molecular crystal show a distinct Coulomb gap and step-like structures. The general features of the tunneling characteristics can be explained by the orthodox SET theory of the double junction system. The measured capacitances of the double junction stay within the range of 10⁻¹⁹ ÷ 10⁻²⁰ F. Moreover, we observe the existance of the negative differential resistance regions of the I/V characteristics. We consider the resonant tunneling via modified electronic states of the combined molecule/graphite system to explain observed phenomenon.

3

Expressions of shallow gas in the Gdansk Basin

63%

Majewski P. , Klusek Z.

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tom R. 52 nr 4 (187)

61-71

EN

In the paper, a short introduction to present-day acoustic and seismoacoustic inventory of shallow gas occurrence and its expression in the Gdansk Basin is presented. Signals of various frequencies and beamforming were employed during surveys conducted from the board of r/v ‘Oceania’. Such a set of diverse acoustic signals was exploited in order to obtain a better recognition of different forms of shallow gas existence in the area. The utilized frequency started from about 1 kHz once a boomer was used in sounding, up to 40–60 kHz in the case a chirp echosounder. At acoustic transects classical echosounders working at 12 and 38 kHz were applied. Some details of the qualitative analysis and the technicalities of the algorithms are given. Variety of examples of echo images obtained in different frequency bands, associated with different forms of gas occurrence is presented.

PL

W artykule dokonano wprowadzenia do współcześnie prowadzonych metodami akustycznymi detekcji i rozpoznawania różnorodności postaci występowania gazu w osadach dennych Basenu Gdańskiego. W celach lepszego rozpoznania form występowania gazu w górnej warstwie osadów w rejsach badawczych r/v „Oceanii” zastosowano sondowanie dna za pomocą sygnałów akustycznych zróżnicowanych pod względem częstotliwości oraz ukształtowania wiązki. Zakres częstotliwości sygnałów akustycznych wykorzystanych w sondowaniu dna zawierał się w granicach od około 1 kHz (boomer) poprzez 12/38 kHz do szerokopasmowych w granicach 40–80 kHz. Na wielu transektach akustycznych do obrazowania ukształtowania dna i warstwy naddanej zastosowano również sonar boczny i echosondę wielowiązkową. W artykule przedstawiono niektóre elementy analizy jakościowej oraz przybliżono szczegóły techniczne algorytmów pozwalających na identyfikację gazu w osadach. Zaprezentowano także liczne przykłady obrazów echa otrzymane dla sygnałów akustycznych w różnych pasmach częstotliwości, powiązanych z występowaniem gazu w osadach.

4

Modeling of nonlinear generation in a bubble layer

63%

Baranowska A. , Klusek Z.

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tom Vol. 12

9-16

EN

The paper presents a numerical approach to modelling the linear and nonlinear scattering at a layer of bubbles. Numerical studies of noncoherent scattering using a Monte Carlo method that can cope with various effects of propagation inside of a bubbles layer such as boundary reflections, scattering anisotropy, sound dispersion, sound attenuation and time dependence are performed. Based on Rayleigh-Plesset bubble's oscillation equation, the propagation and backscattering of signals at bubble population of different size spectra is analyzed. Propagated through the layer and backscattering changes in the signal spectra are studied and modeled according to the properties of bubble populations similar as in the sea.

5

A combined scanning tunneling microscopy/current imaging tunneling spectroscopy study of molecular image contrast of the 8OCB liquid crystal deposited on the HOPG(0001) substrate

63%

Klusek Z. , Kozłowski W.

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2000

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tom Vol. 33, No. 3

350-354

EN

We show investigations of the local density of states of the 80CB/HOPG(0001) sample with high topographic and energetic resolution by thr use of current imaging tunnleing spectroscopy technique. The obtained results lead to the conclusion that the high topographical contrast of the 8OCB/HOPG(0001) system can only be achieved at large negative bias voltage of the sample. In this case the biphenyl groups of the 80CB molecules are seen as a bright rings. It is due to the specific shape of the local density of states below the Fermi level.

6

Krill migration pattern at the ice edge zone (December 1988-January 1989)

63%

Godlewska M. , Klusek Z.

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tom 12

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nr 4

7

The diurnal migration pattern of plankton in the Gulf of Gdansk during storm-induced onshore-offshore bottomwater transport

63%

Klusek Z. , Porazinski K.

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tom 38

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nr 1

8

Acoustic properties of the Pomeranian Bay bottom sediments

63%

Tegowski J. , Klusek Z.

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nr 3

9

Scanning tunneling spectroscopy investigations of gold films deposited on the (0001) basal plane of highly oriented pyrolitic graphite

51%

Klusek Z. , Balcerski J. , Olejniczak W. , Kobierski P.

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tom Vol. 31, No. 3/4

512-515

EN

Gold was thermally evaporated onto (0001) basal plane of highly oriental pyrolitic graphite surface at substrate temperature ranging from 20°C to 600°C. The evaporation rate was varied in the range from 0.02nm/s to 1nm/s. Scanning tunneling microscopy/spectroscopy investigations were carried out in constant current mode under ambient air condition. Gold films exhibit an increasing grain size and grain flattening as the substrate temperature increases and evaporation rate decreases. At higher temperatures (T>300°C) and low evaporation rate (0.02 nm/s) flat terraces with dimension of order 50÷ 250 nm were formed. On the flat terraces scanning tunneling spectroscopy measurements (dI/dV)(I/V) were performed. At the unoccoupied part of the spectra characterstic feature could be distinguished at around 0.6 eV below the Fermi level. The observed feature resembles the well known surface state on the Au(111) plane which exists within the au L2 gap. This is in spite of the fact that spectra were recorded in ambient air conditions.

10

Modular scanning system

51%

Klusek Z. , Olejniczak W. , Pawłowski S. , Kobierski P.

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tom Vol. 31, No. 3/4

508-511

EN

A new, fully computerized scanning tunneling and atomic force microscope system has been designed and built. Both microscope are equipped with fully automatic system of initial approach of the probe tip to the sample. Special construction of the holders ensures an easy replacement of samples and probe tips. The system allows the operation in a wide range of scanning, starting from nanometers to microus using one scanner only (retaining the hight resolution). All functions of the microscopes are fully controlled by personal computer. Due to orginal, clear software written under Windows 3.1/Windows 95 systems on can execute each operation only with a mouse.

11

Geochemical and acoustic evidence for the occurrence of methane in sediments of the Polish sector of the southern Baltic Sea

51%

Brodecka A. , Majewski P. , Bolałek J. , Klusek Z.

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tom No. 55 (4)

951--978

EN

This paper presents the results of geochemical and acoustic investigations of sediments in the Polish sector of the southern Baltic Sea. Its objective was to indicate areas of gas bubble formation and the occurrence of methane. Over 3000 nautical miles of transects were recorded using a variety of hydroacoustic instruments, and five coring points were selected for further analyses of pore waters (CH4, SO4-2, H2S, NH4+, total alkalinity) and sediments (grain size distribution, Corg, Ntot, LOI and WC). Gas turned out to be present at shallow depths in different forms such as recent and buried pockmarks, and gas-saturated sediments (including gas pockets and seepages). It was found that methane was widespread in the sediments of the study area, both in the surface sediments, e.g. in the vicinity of the Hel Peninsula or in the central Gulf of Gdańsk, and in deeper sediment layers, e.g. in the Gdańsk Deep and the Słupsk Furrow. Chemical analysis showed that as a result of the rapid decomposition of organic matter, sulphates were depleted in the top 20 cm layer of sediments and that methane was produced at relatively shallow depths (in some areas even at depths of 20-30 cm bsf) compared to other regions of the Baltic, reaching concentrations of >6 mmol l-1 in the 30-40 cm layer below the sediment surface. The sulphate-methane transition zone (SMTZ) was 4-37 cm thick and was situated in the uppermost 50 cm of the sediments.

12

Observations on relations between marine aerosol fluxes and surface-generated noise in the Southern Baltic Sea

51%

Markuszewski P. , Klusek Z. , Nilsson E. D. , Petelski T.

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tom 62

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nr 4PA

13

Relationships between atmospheric positive electric charge densities and gas bubble concentrations in the Baltic Sea

51%

Klusek Z. , Wiszniewski A. , Jakacki J.

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2004

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tom No. 46 (4)

459-476

EN

Simultaneous measurements of bubble density in the sea subsurface and positive ions in the lower atmosphere were performed in the Baltic Sea in the summer of 1999. Bubbles in two size ranges, around 27 and 100 žm, were measured acoustically. Airborne positive charge was measured with a Gerdien instrument. Observed concentrations of air ions varied from 60 cm-3 up to 600 cm-3. The relative role of bubbles and wind speed on the positive air ion concentrations over the brackish water of the Baltic Sea is discussed. The parameters of a model of a log-log dependence between charge concentration and bubble density are calculated. The correlation functions between time series of concentrations of positive charges over the sea and gas bubbles averaged over a depth range from 0.4 to 4 m and wind speed are presented. There was zero lag between the cross-correlation maxima of charge and bubbles, but there was a phase lag of one and a half hours between charge and wind speed.

14

Investigations of electronic structure of topological defects in carbon nanotubes by scanning tunneling microscopy and current imaging tunneling spectroscopy

51%

Klusek Z. , Byszewski P. , Kowalczyk P.

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2000

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tom Vol. 33, No. 3

355-360

EN

Scanning tunneling microscopy and current imaging tunneling spectroscopy are used to study electronic structure of the five and seven membered fused disclination centers located at the end of the carbon nanotube. Our results show two resonant states at 1.2 eV below and 1.3 eV above the Fermi level. Furthermore the presence of the metallic-semiconductor transition at the end of the carbon nanotube is confirmed.

15

Impact of salinity on the underwater noise generated by small scale air entrainment events

51%

Szuszkiewicz J. , Klusek Z. , Gorska N.

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tom Vol. 20

167--172

EN

Some part of the energy released in the wave breaking process is transformed into the energy of the noise. This sound depends on the water properties, however, there is a lack of reliable data concerning the underwater noise generated by less energetic events. The aim of this study was to understand the impact of salinity on the underwater noise produced during small scale air entrainment events, typical for low wind speed conditions. The tipping trough experiment was performed in a small tank to generate the small scale air injections. Four, linearly placed hydrophones HTI-96-MIN were used to record the acoustic noise accompanying this phenomenon. The bubble plume development, and underwater noise spectra, were compared for salty and fresh water. The potential energy of the modeled events resulted in different spectra, and salinity played an essential role in the emitted underwater noise.

16

Selected characteristics of shipping noise at the fairway of the Gdynia Harbour

51%

Klusek Z. , Szczucka J. , Mróz D.

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tom Vol. 18

203-214

EN

The presented work aims to evaluate the possible impact of shipping noise on the marine fauna in the vicinity of the Gdynia Harbour. Measurements were performed in the area at the distance of 0.2 NM to the fairway. For this purpose, statistics of Sound Pressure Level (SPL), Sound Exposure Level (SEL), and Power Spectral Density (PSD) were evaluated. Some specific changes of the ambient and shipping noise spectra are given in examples.

17

Relationships between atmospheric positive electric charge densities and gas bubble concentrations in the Baltic Sea

51%

Klusek Z. , Wiszniewski A. , Jakacki J.

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2004

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tom 46

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nr 4

EN

Simultaneous measurements of bubble density in the sea subsurface and positive ions in the lower atmosphere were performed in the Baltic Sea in the summer of 1999. Bubbles in two size ranges, around 27 and 100 μm, were measured acoustically. Airborne positive charge was measured with a Gerdien instrument. Observed concentrations of air ions varied from 60 cm−3 up to 600 cm−3. The relative role of bubbles and wind speed on the positive air ion concentrations over the brackish water of the Baltic Sea is discussed. The parameters of a model of a log-log dependence between charge concentration and bubble density are calculated. The correlation functions between time series of concentrations of positive charges over the sea and gas bubbles averaged over a depth range from 0.4 to 4 m and wind speed are presented. There was zero lag between the cross-correlation maxima of charge and bubbles, but there was a phase lag of one and a half hours between charge and wind speed.

18

An attempt to use a broadband acoustic signal for determining the dimensions of Baltic fish

51%

Klusek Z. , Szczucka J. , Rudowski S.

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nr 3

19

Impact of Microphytobenthos Photosynthesis on the Characteristics of the Echo Signal from Baltic Sandy Sediments

45%

Gorska N. , Kowalska-Duda E. , Marszal J. , Schmidt J. , Klusek Z.

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2015

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tom Vol. 40, No. 3

395--405

EN

The understanding the influence of biological processes on the characteristics of the signals backscattered by the sea floor is crucial in the development of the hydroacoustical benthic habitat classification techniques. The impact of the microphytobenthos photosynthesis on the acoustical backscattering properties of the Atlantic sandy sediments was previously demonstrated by Holliday et al. (2004) and Wildman and Huettel (2012). To account for the sensitivity of the hydroacoustical classification techniques to the backscattering properties of local marine sediments, it is important to understand the microphytobenthos photosynthesis impact for the Baltic Sea where the techniques are being actively developed now. This is the main motivation of the paper. In the paper the influence of the microphytobenthos photosynthesis on the characteristics of the echo signals reflected by sandy sediments in the typical Baltic temperature and the salinity conditions is discussed. The interdisciplinary multiday laboratory experiment was conducted to study the impact of benthic microalgal photosynthesis on the characteristics of the echo signal reflected by sandy sediments. Hydroacoustical data were collected under controlled constant light, temperature and salinity conditions. The oxygen content at different levels of the water column was simultaneously monitored.