Autor: Witek, P. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Modelling of small river deltas : the dependence of morphology on grain size and discharge
Autorzy:: Witek, P.
Czechowski, L.
Misiura, K.
Tematy:: hydrology
sedimentology
river deltas
numerical modelling; Pokaż więcej
Wydawca:: Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/2060519.pdf Link otwiera się w nowym oknie
Opis:: We studied the dependence of the morphology of small river deltas on the grain size, the total discharge, and the slope of the deposits. We use Computational Fluid Dynamics (CFD) methods of numerical modelling. For all models we used the same initial geometry of the river valley and a portion of the lake. Our simulations show the expected dependence of the shape of our simulated small deltas on the grain size. Moreover, we find that the final type of delta could be characterized by the average slope in the region close to the delta front.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: The formation of single-channel and multiple-channel rivers on large slopes
Autorzy:: Misiura, K.
Czechowski, L.
Witek, P.
Bendiukova, A.
Tematy:: river classification
multiple channel rivers
single channel river
sedimentation; Pokaż więcej
Wydawca:: Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/2060527.pdf Link otwiera się w nowym oknie
Opis:: We investigated the formation of different types of rivers depending on slope, total discharge, and grain size. Calculations were performed using numerical package CCHE2D, developed by the National Center for Computational Hydroscience and Engineering. The model is based on the Navier-Stokes equations for depth-integrated two-dimensional turbulent flow and the three-dimensional convection-diffusion equation of sediment transport. For each model we use the same river geometry, suspended load concentration, and bedload transport rate. We distinguish three types of rivers using two methods for classification (single-channel, multiple-channels and transitional). We found that the trend line for transitional rivers is an increasing function of Q in space (Q, d) and that for large S the number of multichannel rivers decreases.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Specyfika sieci monitorujących wody podziemne na obszarze Karpat
The specificity of the groundwater monitoring network in the Carpathians
Autorzy:: Freiwald, P.
Owsiak, P.
Witek, K.
Tematy:: Karpaty
monitoring wód podziemnych
cykle hydrogeologiczne
Carpathians
groundwater monitoring
hydrogeological cycles; Pokaż więcej
Wydawca:: Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/2062160.pdf Link otwiera się w nowym oknie
Opis:: Sieć obserwacyjno-badawcza wód podziemnych na obszarze Karpat jest prowadzona przez Oddział Karpacki Państwowego Instytutu Geologicznego – Państwowego Instytutu Badawczego od 1989 r. Monitoringowi podlegają wahania zwierciadeł wód podziemnych w otworach hydrogeologicznych, studniach kopanych i wydajności źródeł oraz stan chemiczny wód podziemnych. Obecnie (2013 r.), w ramach państwowej służby hydrogeologicznej, obserwacje są prowadzone w 86 punktach badawczych, z czego 48 stanowią studnie wiercone, 34 źródła i 4 studnie kopane. Do specyfiki obszarów górskich, w szczególności Karpat, należy duża gęstość występowania źródeł (nawet powyżej 10 na km2). Ich udział w sieci obserwacyjno-badawczej wód podziemnych stanowi 39% wszystkich punktów obserwacyjnych. Wydajność źródeł jest bardzo zmienna i uwarunkowana ich pozycją morfologiczną, litologią warstwy wodonośnej i tektoniką górotworu. Na obszarze Karpat w wielu punktach obserwacyjnych wyraźnie zaznaczają się wieloletnie (około 20 lat), cykliczne zmiany wydajności źródeł i wahań zwierciadła wód podziemnych.
Observation and research network of groundwater in the Carpathian area is carried out by the Carpathian Branch of the Polish Geological Institute – National Research Institute since 1989. The subjects of the monitoring are dynamics and chemical status of groundwater. The Polish Hydrogeological Survey presently (2013) keeps observations in 86 studied points. Among them 48 are drilled wells, 34 springs, and 4 dug wells. High density of spring occurrence is a characteristic feature of mountain areas, particularly for the Carpathians, where even more than 10 springs per km2 are noted. They constitute 39% of all observation points of the groundwater observation and research network. The spring discharge is very variable and depends on the morphological position of the spring, aquifer lithology, and tectonics of the orogen. In the Carpathian region in many observation points long-term (ca. 20 years) cyclic changes in spring discharges and fluctuations of the groundwater table are clearly visible.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Analiza oddziaływań antropogenicznych na obszary solniskowe w dolinie Parsęty
Analysis of anthropogenic influences on the saline territories within Parsęta valley
Autorzy:: Pieńkowski, P.
Bosiacka, B.
Witek, M.
Tematy:: antropopresja
solnisko
dolina Parsęty
Natura 2000
anthropopression
salt marsh
Parsęta valley; Pokaż więcej
Wydawca:: Polskie Towarzystwo Geograficzne
Powiązania:: https://bibliotekanauki.pl/articles/88144.pdf Link otwiera się w nowym oknie
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Research and Medical Transcranial Doppler System
Autorzy:: Lewandowski, M.
Walczak, M.
Karwat, P.
Witek, B.
Karłowicz, P.
Tematy:: Doppler system
digital signal processing
hardware-software partitioning
field programmable gate array (FPGA); Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/177389.pdf Link otwiera się w nowym oknie
Opis:: A new ultrasound digital transcranial Doppler system (digiTDS) is introduced. The digiTDS enables diagnosis of intracranial vessels which are rather difficult to penetrate for standard systems. The device can display a color map of flow velocities (in time-depth domain) and a spectrogram of a Doppler signal obtained at particular depth. The system offers a multigate processing which allows to display a numer of spectrograms simultaneously and to reconstruct a flow velocity profile. The digital signal processing in digiTDS is partitioned between hardware and software parts. The hardware part (based on FPGA) executes a signal demodulation and reduces data stream. The software part (PC) performs the Doppler processing and display tasks. The hardware-software partitioning allowed to build a flexible Doppler platform at a relatively low cost. The digiTDS design fulfills all necessary medical standards being a new useful tool in the transcranial field as well as in heart velocimetry research.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Biocide testing for the application in the oil and gas industry
Autorzy:: Turkiewicz, A
Brzeszcz, J.
Witek, W.
Kapusta, P.
Tematy:: biocide
microorganisms
triazine
peroxide
drilling fluid
biocidal activity; Pokaż więcej
Wydawca:: Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Powiązania:: https://bibliotekanauki.pl/articles/298882.pdf Link otwiera się w nowym oknie
Opis:: The paper discusses tests for effectiveness of three antibacterial substances for application in the national oil and gas industry. The substances were tested with reference to active cultures of microorganisms. These cultures were isolated, inter alia, from drilling fluids, produced waters and extraction sludge, and then multiplied and used in tests discussed in this publication. The tests demonstrated differences in particular tested substances in respect of effectiveness of their impact on aerobic and anaerobic bacteria and fungi. The results of the work will be used in industrial treatments in order to eliminate biogenic contamination, counteract biodegradation of drilling muds, and also for disinfection of reservoirs designed for storing water and other technological fluids.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Fabrication and characterization of composite materials based on porous ceramic preform infiltrated by elastomer
Autorzy:: Chabera, P.
Boczkowska, A.
Witek, A.
Oziębło, A.
Tematy:: ceramic matrix composites
ceramic
mechanical properties
damage mechanics
scanning electron microscopy
kompozyty z matrycą ceramiczną
ceramika
właściwości mechaniczne
mechanika szkód
skaningowa mikroskopia elektronowa; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/202111.pdf Link otwiera się w nowym oknie
Opis:: The paper presents the experimental results of fabrication and characterization of ceramic- elastomer composites. They were obtained using pressure infiltration of porous ceramics by elastomer As a result the composites in which two phases are interpenetrating three-dimensionally and topologically throughout the microstructure were obtained. In order to enhance mechanical properties of preforms a high isostatic pressure method was utilized. The obtained ceramic preforms with porosity gradient within the range of 20-40% as well as composites were characterized by X-ray tomography. The effect of volume fraction of pores on residual porosity of composites was examined. These results are in accordance with SEM images which show the microstructure of composites without any delaminations and voids. Such composites exhibit a high initial strength with the ability to sustain large deformations due to combining the ceramic stiffness and rubbery elasticity of elastomer. Static compression tests for the obtained composites were carried out and the energy dissipated during compression was calculated as the area under the stress-strain curve. The dynamic behavior of the composite was investigated using the split Hopkinson pressure bar technique. It was found that ceramic-elastomer composites effectively dissipate the energy. Moreover, a ballistic test was carried out using armor piercing bullets.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Jakość trofealna muflonów tryków pozyskanych w Górach Bardzkich
Trophy quality of mouflons in the Bardzkie Mountains
Autorzy:: Wajdzik, M.
Witek, K.
Nasiadka, P.
Skubis, J.
Tematy:: lowiectwo
Gory Bardzkie
zwierzyna plowa
muflon
Ovis musimon
tryki
trofea lowieckie
slimy
jakosc
mouflon
horns
bardzkie mountains
cic; Pokaż więcej
Wydawca:: Polskie Towarzystwo Leśne
Powiązania:: https://bibliotekanauki.pl/articles/991359.pdf Link otwiera się w nowym oknie
Opis:: The aim of the study was to characterize individual quality of mouflon harvested in the Bardzkie Mountains (south−west Poland). The assessment criteria included horn dimensions, i.e. their length, circumference (base, middle and top), spread and twist. These features were individually analyzed for each mouflon ram. Medal value of the trophies expressed as CIC scores increased with the ram age reaching 187.12 for 6−years−old animals. Three out of 50 measured trophies were classified into the bronze medal category, as they crossed the threshold of 185 CIC points. All medal−winning individuals were 6 years old.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Quantum chemical modeling of electrochromism of tungsten oxide films
Autorzy:: Góra, Artur
Witek, A.
Liguzinski, P.
Petelenz, Piotr
Brocławik, Ewa
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 10.

Tytuł:: Comparison of numerical and experimental study of armour system based on alumina and silicon carbide ceramics
Autorzy:: Chabera, P.
Boczkowska, A.
Morka, A.
Kędzierski, P.
Niezgoda, T.
Oziębło, A.
Witek, A.
Tematy:: ballistic performance
numerical simulation
armour
alumina ceramic
silicon carbide ceramic
ceramic-elastomer composites
wydajność balistyczna
symulacja numeryczna
zbroja
kompozyt ceramika-elastomer; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/202054.pdf Link otwiera się w nowym oknie
Opis:: The main goal of this numerical and experimental study of composite armour systems was to investigate their ballistic behaviour. Numerical simulations were employed to determine the initial dimensions of panel layers before the actual ballistic test. In order to achieve this aim, multivariate computations with different thicknesses of panel layers were conducted. Numerical calculations were performed with the finite element method in the LS-DYNA software, which is a commonly used tool for solving problems associated with shock wave propagation, blasts and impacts. An axisymmetric model was built in order to ensure sufficient discretization. Results of a simulation study allowed thicknesses of layers ensuring assumed level of protection to be determined. According to the simulation results two armour configurations with different ceramics have been fabricated. The composite armour systems consisted of the front layer made of Al2O3 or SiC ceramic and high strength steel as the backing material. The ballistic performance of the proposed protective structures were tested with the use of 7.62 mm Armour Piercing (AP) projectile. A comparison of impact resistance of two defence systems with different ceramic has been carried out. Application of silicon carbide ceramic improved ballistic performance, as evidenced by smaller deformations of the second layer. In addition, one of armour systems was complemented with an intermediate ceramic-elastomer layer. A ceramic-elastomer component was obtained using pressure infiltration of gradient porous ceramic by elastomer. Upon ballistic impact, the ceramic body dissipated kinetic energy of the projectile. The residual energy was absorbed by the intermediate composite layer. It was found, that application of composite plates as a support of a ceramic body provided a decrease of the bullet penetration depth.
Dostawca treści:: Biblioteka Nauki

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