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Wyszukujesz frazę "Dobak, P. J." wg kryterium: Autor


Wyświetlanie 1-10 z 10
Tytuł:
Preliminary investigations of creep strain of Neogene clay from Warsaw in drained triaxial tests assisted by computed microtomography
Autorzy:
Kaczmarek, Ł. D.
Dobak, P. J.
Kiełbasiński, K.
Powiązania:
https://bibliotekanauki.pl/articles/178669.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
microstructure
multistage creep tests
strain rate
undisturbed Neogene clay
Opis:
The study concerns soil creep deformation in multistage triaxial stress tests under drained conditions. High resolution X-ray computed microtomography (XμCT) was involved in structure recognition before and after triaxial tests. Undisturbed Neogene clay samples, which are widespread in central Poland, were used in this study. XμCT was used to identify representative sample series and informed the detection and rejection of unreliable ones. Maximum deviatoric stress for in situ stress confining condition was equal 95.1 kPa. This result helped in the design of further multistage investigations. The study identified the rheological strain course, which can be broken down into three characterizations: decreasing creep strain rate, transitional constant creep velocity, and accelerating creep deformation. The study found that due to multistage creep loading, the samples were strengthened. Furthermore, there is a visibly “brittle” character of failure, which may be the consequence of the microstructure transformation as a function of time as well as collapse of voids. Due to the glacial tectonic history of the analyzed samples, the reactivation of microcracks might also serve as an explanation. The number of the various sizes of shear planes after failure is confirmed by XμCT overexposure.
Źródło:
Studia Geotechnica et Mechanica; 2017, 39, 2; 35-49
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of soil permeability from consolidation analysis based on Terzaghi’s and Biot’s theory
Autorzy:
Dobak, P.
Gaszyński, J.
Powiązania:
https://bibliotekanauki.pl/articles/2060271.pdf
Data publikacji:
2015
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
consolidation
cohesive soils
Terzaghi’s theory
Biot’s theory
permeability
geological barriers
insulation properties
Opis:
Proper evaluation of permeability parameters has a crucial signification in multi-scale prediction of consolidation. Drainage path is connected with the time of one-dimensional consolidation in Terzaghi’s theory and numerous later solutions. That is why the evaluation of permeability factor allows to model the settlement’s time of geological layers based on results obtained on a laboratory scale. Numerous tests show a difference of the consolidation degree obtained from one-dimensional strain course and pore pressure distribution. Evaluation of consolidation coefficient cv based on a newly proposed method allows better understanding of the basic reasons of unconventional behaviour of tested soils. Unparallel characteristics of strain and pore pressure distribution show important role of soil’s skeleton creep and its relation to permeability aspects. Solutions proposed by Biot’s theory allow analysing the different velocity of strain and pore pressure distribution. The article presents a new approximated method based on Terzaghi’s theory and evaluation of parameters which are necessary in application of Biot’s one–dimensional solution. These parameters are connected with compressibility and coefficient of permeability. The goal of presented methodological studies is comparison between permeability obtained from application of Terzaghi’s and Biot’s theory. It allows trying to explain physical reasons of differences between applied models and testing results, and improving the methodology of one–dimensional consolidations tests.
Źródło:
Geological Quarterly; 2015, 59, 2; 373--381
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Role of Temperature on the Magnetization Process in CoFeZrB/FeCuNbMoSiB Hybrid Ferromagnets
Autorzy:
Dobák, S.
Füzer, J.
Kollár, P.
Powiązania:
https://bibliotekanauki.pl/articles/1032660.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Bb
75.50.Kj
75.50.Tt
75.60.Ch
75.60.Ej
75.30.Gw
85.70.-w
Opis:
The study presents magnetization process behaviour versus operating temperature up to 100°C in dual-phase ferromagnets in the light of their complex permeability spectra and energy losses from quasi-dc regime up to about 1 MHz upon defined peak induction. The samples consist of two Co- and Fe-based ball-milled-ribbon powders mixed in the same mass ratio. The magnetic characterization has been carried out by a digital hysteresisgraph-wattmeter using complex permeability approach to the linear material.
Temperature invoked reduction of anisotropy leads to the decrease of hysteresis losses and significantly affects the low-frequency part of permeability and losses that is ascribed to domain wall movement. The high-frequency behaviour remains unchanged with respect to increase of temperature.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 696-698
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charakterystyka hydrochemiczna wód w rejonie Polskiej Stacji Polarnej im. H. Arctowskiego na Wyspie Króla Jerzego (Szetlandy Południowe)
Hydrochemical characteristics of water in the area of Arctowski Polish Polar Station on King George Island (Southern Shetlands)
Autorzy:
Krogulec, T.
Krogulec, E.
Małecki, J.
Pietrzykowski, P.
Dobak, P.
Powiązania:
https://bibliotekanauki.pl/articles/2075628.pdf
Data publikacji:
2017
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Szetlandy Południowe
Polska Stacja Polarna im. H. Arctowskiego
wody podziemne
woda powierzchniowa
Southern Shetlands
Arctowski Polish Polar Station
groundwater
surface water
Opis:
The research was carried out during Antarctic summer 2015/2016 in the region of Arctowski Polish Polar Station on King George Island (Southern Shetlands) in Admiralty Bay in Antarctica. The scope of hydrochemical studies included selected elements: temperature, pH, dry residue, general slurry, ammonium ion, nitrates, macroelements (chlorides, sulphates, magnesium, bicarbonates and carbonates, sodium, magnesium and calcium) and some microelements. Surface water and groundwater are low mineralized and do not show anthropogenic impact. The results ofphysicochemical tests have been compared with marine water chemistry and few available archival data, which allowed the assessment of water quality and the attempt to identify the groundwater flow direction.
Źródło:
Przegląd Geologiczny; 2017, 65, 11/2; 1306--1311
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dokumentowanie geologiczne na potrzeby posadowienia obiektów naukowej stacji badawczej w warunkach polarnych
Geological investigations reporting in polar conditions for civil engineering at the example of the construction of research station
Autorzy:
Pietrzykowski, P.
Dobak, P.
Krogulec, E.
Krogulec, T.
Małecki, J.
Powiązania:
https://bibliotekanauki.pl/articles/2075722.pdf
Data publikacji:
2017
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
geologia inżynierska
Antarktyda
stacja polarna
Stacja Antarktyczna im. Henryka Arctowskiego
engineering geology
Antarctica
Arctowski Polar Station
Opis:
The methodological experience and the results of observation and research have been presented as a part of an expert geological and engineering study for the planned extension of the Henryk Arctowski Polar Station on the coast of King George Island in the South Shetland Islands in Antarctica. The object is realized in an area requiring recognition of specific geodynamic conditions. According to technical requirements coming from the conceptual design project of the station (Kurylowicz and Associates, 2015) it was necessary to adopt a non-standard research program. Engineering and geological characteristics are presented in comparison with geoenvironmental considerations. The assessment of soil and rock properties was carried out in relation to the results of observations and determinations of parameters that could be assessed in the coarse-grained soils and rocks in the area of the designed object.
Źródło:
Przegląd Geologiczny; 2017, 65, 10/2; 692--700
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microwave Sintered Fe/MgO Soft Magnetic Composite
Autorzy:
Bureš, R.
Fáberová, M.
Kollár, P.
Füzer, J.
Dobák, S.
Onderko, F.
Kurek, P.
Powiązania:
https://bibliotekanauki.pl/articles/1032291.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.-t
75.50.-y
62.20.-x
Opis:
Micro/nano soft magnetic composite based on the Fe microparticles and the MgO nanoparticles was prepared by cold pressing followed by microwave sintering. Magnetic and mechanical properties of the green compact as well as sintered samples were measured. Coercivity, permeability, resistivity, elastic modulus and transverse rupture strength values in dependence on MgO content were investigated. The influence of MgO content ratio on properties was different in the case of as pressed green samples in comparison to sintered bodies. Microstructure formation and its influence on mechanical and magnetic properties are discussed. The coercivity of the green compacts with 1-5 wt% of MgO exhibits approximately 460 A/m and after sintering decreases to approximately 290 A/m. The real part of complex permeability at the frequency of 100 kHz exhibits a maximum for 2 wt% of MgO in green compacts, while for 10 wt% in sintered samples. It was observed that increase of the content of MgO causes decrease of the permeability. Properties of the sintered composite are related to formation of magnesium ferrite as well as volume distribution of residual MgO in dependence on initial MgO ratio.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 780-782
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Sintered Fe₅₀Co₅₀ Powder Cores
Autorzy:
Olekšáková, D.
Kollár, P.
Füzer, J.
Onderko, F.
Dobák, S.
Viňáš, J.
Fáberová, M.
Bureš, R.
Powiązania:
https://bibliotekanauki.pl/articles/1032708.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Vv
85.70.-w
75.50.Bb
Opis:
We investigated coercivity, total losses and complex permeability of sintered Fe-Co powder cores to detect magnetization processes performing in ac magnetic field. The Fe-Co solid solution alloy powders with 50:50 wt% ratio were prepared by 1, 15, and 20 h alloyed mixture of pure chemical elements in planetary ball mill. The resulting powder was subsequently sintered into a disk form. The compaction was performed at a pressure of 800 MPa for 5 min at temperatures of 400°C, 500°C and 600°C in vacuum oxidation protective atmosphere, with pressure of 5×10¯³ Pa. The best magnetic properties exhibit sample prepared from 1 h alloyed powder, compacted at 600°C.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 807-809
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stress-strain behaviour analysis of Middle Polish glacial tills from Warsaw (Poland) based on the interpretation of advanced field and laboratory tests
Autorzy:
Bąkowska, A.
Dobak, P.
Gawriuczenkow, I.
Kiełbasiński, K.
Szczepański, T.
Trzciński, J.
Wójcik, E.
Zawrzykraj, P.
Powiązania:
https://bibliotekanauki.pl/articles/139030.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
glacial tills
Warsaw
compressibility
strength
advanced tests
glina lodowcowa
Warszawa
ściśliwość
wytrzymałość
testy
Opis:
The selected parameters of the Wartanian and Odranian tills, with relation to their spatial occurrence, grain size distribution, mineralogical composition, matric suction and other physical characteristics, are presented. The assessment of the lithogenesis and stress history on the microstructure is attempted. The comparison of the compression and permeability characteristics from field and laboratory tests has been performed. Laboratory consolidation tests carried out with up to 20MPa vertical stress, revealed two yield stress values, one in the range of a couple hundreds kPa, the other in the range of a couple thousands kPa. Based on those results, the reliability of the soil preconsolidation assessment, with the use of the two different methods is discussed. The aspect of the triaxial strength reduction under the dynamic loading of diverse frequency and amplitude is raised. The research results depict a variety of possible geological-engineering characteristics, under the divergent constraints scenarios, of compression or strength weakening origin. The effects of the specialized research program will widen the possibilities of physio-mechanical and structural characterization of soils for geological-engineering purposes.
Źródło:
Acta Geologica Polonica; 2016, 66, 3; 561-585
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of NiZnFe₂O₄ content on magnetic properties of supermalloy type material
Autorzy:
Ďáková, L'.
Füzer, J.
Dobák, S.
Kollár, P.
Fáberová, M.
Strečková, M.
Bureš, R.
Hadraba, H.
Powiązania:
https://bibliotekanauki.pl/articles/1053020.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.55.-w
75.60.-d
75.50.Bb
75.50.Gg
Opis:
Soft magnetic composites represent a remarkable kind of materials with wide variety of use. Magnetic properties are dependent on the materials composition and also on the method of preparation. Ni-Fe-Mo alloys (supermalloy) have high complex permeability and low eddy current losses. Soft magnetic NiZnFe₂O₄ ferrites have low coercivity and intermediate saturation magnetization. The Ni_{80}Fe_{14.7}Mo_{4.5}Mn_{0.5}Si_{0.3} (wt%) powder sample was prepared by mechanical alloying of the chemical elements for 24 h. Ni_{0.3}Zn_{0.7}Fe₂O₄ ferrite is commercially available by Sigma Aldrich. Both powders were mixed at selected ratio and uniaxially compacted at 800 MPa. In this paper, we report the experimental observations of the effects of Ni_{0.3}Zn_{0.7}Fe₂O₄ content on the electromagnetic properties of NiFeMoMnSi/Ni_{0.3}Zn_{0.7}Fe₂O₄. The samples contained 5, 10, and 15% of Ni_{0.3}Zn_{0.7}Fe₂O₄ ferrite and were sintered for 30 min at 800°C. An addition of Ni_{0.3}Zn_{0.7}Fe₂O₄ ferrite caused decrease of complex permeability and increase coercivity of the samples. The 5% of Ni_{0.3}Zn_{0.7}Fe₂O₄ sample exhibits the highest value of the real part of complex permeability (48 at 1 kHz). The 10% of Ni_{0.3}Zn_{0.7}Fe₂O₄ sample showed the lowest total magnetic losses.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 813-815
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
DC Magnetic Properties and Complex Permeability of Ni-Fe Based Composites
Autorzy:
Onderko, F.
Jakubčin, M.
Dobák, S.
Olekšáková, D.
Birčáková, Z.
Kollár, P.
Füzer, J.
Fáberová, M.
Bureš, R.
Kurek, P.
Powiązania:
https://bibliotekanauki.pl/articles/1032820.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Bb
75.60.Jk
75.60.-d
Opis:
We have investigated soft magnetic composite materials to better understand the influence of binder (resin) content on the DC magnetic properties and the complex permeability. Soft magnetic composite samples were composed from NiFe powder with phenol formaldehyde resin (ATM). Ferromagnetic magnetic powder for ring-shaped samples was obtained by milling of small pieces cut of NiFe sheets. The obtained powder was annealed to partially remove structural defects. The prepared powder was mixed with phenol-formaldehyde resin in different vol.%. The mixtures were pressed into the ring-shape samples. Complex permeability and DC magnetic properties (initial magnetization curves, anhysteretic curves and hysteresis loops) were measured. Higher inner demagnetizing fields in the resin containing samples were responsible for higher coercivity and hysteresis losses, but the permeability was stable up to much higher frequencies, compared to the sample without the resin.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 792-794
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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