Wszystkie pola: Laskowski, R. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: A new program for radical tessellation construction and analysis
Autorzy:: Laskowski, R.
Powiązania:: https://bibliotekanauki.pl/articles/1954547.pdf
Data publikacji:: 2000
Wydawca:: Politechnika Gdańska
Tematy:: radical tessellation
stochastic geomerty
structure recognition
computer modelling
Opis:: The purpose of the work is to describe use of the computer program SIMPL designed for construction and analysis of radical tessellations of any computer simulated sample. The radical polyhedra (RP) Gellatly and Finney, J. Non-Cryst. Solids, vol. 50, p. 313 (1982) can be considered as a generalization of the Voronoi polyhedra more widely used in literature. An RP is a minimal polyhedron whose faces are sets of such points that distances from the points to tangent points of two neighboring atomic spheres are equal. The tessellation technique is a very effective tool for structural analysis of computer simulated samples, giving a great amount of easily accessible information. SIMPL allows to construct an RP network for a defined system and analyze the shape, composition and mutual geometrical relation of radical polyhedra and radical simplices. Implemented capabilities give, for example, the possibility of recognizing an atomic environments' shape and investigating the non-local order in computer simulated materials. The pattern recognition technique Laskowski R. et al., TASK Quart., vol. 1, p. 96 (1997) is based on analysis of the shape of the radical polyhedra, and contraction of short edges and small faces of the polyhedra. Non-local order analysis involves geometric relations between tessellation simplices.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2000, 4, 4; 531-553
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 2.

Tytuł:: A new program for radical tessellation construction and analysis
Autorzy:: Laskowski, R.
Powiązania:: https://bibliotekanauki.pl/articles/1954550.pdf
Data publikacji:: 2000
Wydawca:: Politechnika Gdańska
Tematy:: radical tessellation
stochastic geomerty
structure recognition
computer modelling
Opis:: The purpose of the work is to describe use of the computer program SIMPL designed for construction and analysis of radical tessellations of any computer simulated sample. The radical polyhedra (RP) Gellatly and Finney, J. Non-Cryst. Solids, vol. 50, p. 313 (1982) can be considered as a generalization of the Voronoi polyhedra more widely used in literature. An RP is a minimal polyhedron whose faces are sets of such points that distances from the points to tangent points of two neighboring atomic spheres are equal. The tessellation technique is a very effective tool for structural analysis of computer simulated samples, giving a great amount of easily accessible information. SIMPL allows to construct an RP network for a defined system and analyze the shape, composition and mutual geometrical relation of radical polyhedra and radical simplices. Implemented capabilities give, for example, the possibility of recognizing an atomic environments' shape and investigating the non-local order in computer simulated materials. The pattern recognition technique Laskowski R. et al., TASK Quart., vol. 1, p. 96 (1997) is based on analysis of the shape of the radical polyhedra, and contraction of short edges and small faces of the polyhedra. Non-local order analysis involves geometric relations between tessellation simplices.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2000, 4, 4; 531-553
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 3.

Tytuł:: Fault Tree Analysis as a tool for modelling the marine main engine reliability structure
Autorzy:: Laskowski, R.
Powiązania:: https://bibliotekanauki.pl/articles/135108.pdf
Data publikacji:: 2015
Wydawca:: Akademia Morska w Szczecinie. Wydawnictwo AMSz
Tematy:: Fault Tree Analysis (FTA)
main engine
reliability
weak link
Reliability Block Diagram (RBD)
qualitative analysis
minimal cut sets
Opis:: The introduction to the Fault Tree Analysis has been presented in this article. Selected publications on the Fault Tree Analysis have been listed. The usefulness of the method in marine engineering application has been indicated. Reliability testing facility has been presented, that is typical two-stroke, slow-speed ship crosshead Diesel engine intended to power the ship. The way of creating system model with the Fault Tree Analysis application has been presented. Reliability structure of tested engine has been modelled using Reliability Block Diagrams, as well as the Fault Tree Analysis. Main tree describing the object reliability structure analysis and the sub-tree structure modelling crank system, subsystem of the cam shaft, cylinder exemplary system and turbocharger have been built. Qualitative analysis of the tree has been conducted – the minimal cut sets of the system has been determined. The directions for further research have been indicated.
Źródło:: Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2015, 41 (113); 71-77
1733-8670
2392-0378
Pojawia się w:: Zeszyty Naukowe Akademii Morskiej w Szczecinie
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 4.

Tytuł:: Pestycydy: za czy przeciw?
Autorzy:: Laskowski, R.
Powiązania:: https://bibliotekanauki.pl/articles/845762.pdf
Data publikacji:: 2010
Wydawca:: Polskie Towarzystwo Przyrodników im. Kopernika
Tematy:: srodki ochrony roslin
pestycydy
insektycydy
DDT
insektycydy naturalne
pyretryna
rotenon
insektycydy syntetyczne
zwiazki chloroorganiczne
zwiazki fosforoorganiczne
pyretroidy
rotenoidy
karbaminiany
chloronikotynyle
mechanizm dzialania
stosowanie
oddzialywanie na zwierzeta
skutki uboczne
skutki negatywne
skazenia srodowiska
Źródło:: Wszechświat; 2010, 111, 01-03; 39-44
0043-9592
Pojawia się w:: Wszechświat
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 5.

Tytuł:: Maximum entropy generation rate in a heat exchanger at constant inlet parameters
Autorzy:: Laskowski, R.
Jaworski, M.
Powiązania:: https://bibliotekanauki.pl/articles/95303.pdf
Data publikacji:: 2017
Wydawca:: Politechnika Koszalińska. Wydawnictwo Uczelniane
Tematy:: maximum entropy generation rate
entropy
heat exchanger
maksymalna szybkość generowania entropii
entropia
wymiennik ciepła
Opis:: The main goal of the paper is to provide a condition for which a maximum entropy generation occurs in a heat exchanger at constant inlet parameters (temperatures and mass flow rates). Knowing this condition is essential during the design of the heat exchanger as it allows designers to avoid one of its most unfavourable operating conditions in terms of thermodynamics. Entropy generation resulting from the resistance of heat-transferring fluids to flow was not taken into account. Entropy generation was analysed as a function of a heat flow rate at constant parameters at the inlet of a condenser and a counter-flow double-pipe heat exchanger. The analysis showed that for the condenser the entropy generation rate increases with the increase in the heat flow rate. The maximum entropy generation rate occurs for the maximum flow rate of the heat that can be transferred according to the definition of heat transfer effectiveness. For the counter-flow heat exchanger, the entropy generation as a function of the heat flow rate reaches maximum at constant inlet parameters (temperatures and mass flow rates). It appeared that the peak entropy generation, or the largest exergy loss, occurs when the outlet temperatures of the fluids are equal. This assertion was verified against data obtained from a simulator of the counter-flow heat exchanger for two different relations between heat capacity rates.
Źródło:: Journal of Mechanical and Energy Engineering; 2017, 1, 1; 79-86
2544-0780
2544-1671
Pojawia się w:: Journal of Mechanical and Energy Engineering
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 6.

Tytuł:: Thermal-hydraulic calculations for a fuel assembly in a European Pressurized Reactor using the RELAP5 code
Autorzy:: Skrzypek, M.
Laskowski, R.
Powiązania:: https://bibliotekanauki.pl/articles/148264.pdf
Data publikacji:: 2015
Wydawca:: Instytut Chemii i Techniki Jądrowej
Tematy:: fuel assembly
pressurized water reactor (PWR)
safety analysis
RELAP5
Opis:: The main object of interest was a typical fuel assembly, which constitutes a core of the nuclear reactor. The aim of the paper is to describe the phenomena and calculate thermal-hydraulic characteristic parameters in the fuel assembly for a European Pressurized Reactor (EPR). To perform thermal-hydraulic calculations, the RELAP5 code was used. This code allows to simulate steady and transient states for reactor applications. It is also an appropriate calculation tool in the event of a loss-of-coolant accident in light water reactors. The fuel assembly model with nodalization in the RELAP5 (Reactor Excursion and Leak Analysis Program) code was presented. The calculations of two steady states for the fuel assembly were performed: the nominal steady-state conditions and the coolant flow rate decreased to 60% of the nominal EPR flow rate. The calculation for one transient state for a linearly decreasing flow rate of coolant was simulated until a new level was stabilized and SCRAM occurred. To check the correctness of the obtained results, the authors compared them against the reactor technical documentation available in the bibliography. The obtained results concerning steady states nearly match the design data. The hypothetical transient showed the importance of the need for correct cooling in the reactor during occurrences exceeding normal operation. The performed analysis indicated consequences of the coolant flow rate limitations during the reactor operation.
Źródło:: Nukleonika; 2015, 60, No. 3, part 2; 537-544
0029-5922
1508-5791
Pojawia się w:: Nukleonika
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 7.

Tytuł:: The influence of low density behaviour of state equation on lattice inverted pair potential for lead
Autorzy:: Laskowski, R.
Chybicki, M.
Powiązania:: https://bibliotekanauki.pl/articles/1954520.pdf
Data publikacji:: 1999
Wydawca:: Politechnika Gdańska
Tematy:: lattice inversion technique
pair potential
molecular simulations
Opis:: A pair potential for lead (Pb) is extracted from the ab-initio energy-volume data using the lattice inversion procedure of Carlsson and co-workers [Phil. Mag. 41 (1980), p. 241]. Because of a limited accuracy of the ab-initio techniques, we extrapolate the energy-volume data for low-density systems with suitable analytical tail functions. We discuss the dependence of the molecular dynamics (MD) simulation structural results and the elastic modules on the choice of the cohesive energy tail function. The MD-simulated radial distribution functions (RDFs), obtained for several energy tails, in several temperatures are discussed.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1999, 3, 3; 303-312
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 8.

Tytuł:: A simplified mathematical model of a U-tube steam generator under variable load conditions
Autorzy:: Laskowski, R.
Lewandowski, J.
Powiązania:: https://bibliotekanauki.pl/articles/240139.pdf
Data publikacji:: 2013
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: steam generator
mathematical model under variable load conditions
wytwornica pary
model matematyczny
zmienne warunki obciążenia
Opis:: A steam generator in a nuclear power plant with a light water reactor is a heat exchanger, in which the heat is being transferred from the primary to the secondary loop (it links the primary and secondary loops). When the power plant is running, the inlet parameters (temperatures and mass flow rates) on both sides of the steam generator can change. It is important to know how the changes of these parameters affect the steam generator performance. The complexity of the processes taking place in the steam generator makes it difficult to create a simulator reflecting its performance under changed conditions. In order to simplify the task, the steam generator was considered as a ‘black box’ with the aim of examining how the changes of the inlet parameters affect the changes of the outlet ones. On the basis of the system (steam generator) response, a simple mathematical model of the steam generator under variable load conditions was proposed. In the proposed model, there are two dimensionless parameters and three constant coefficients. A linear relation between these dimensionless parameters was obtained. The correctness of the model was verified against the data obtained with a steam generator simulator for European Pressured Reactor and AP-600 reactors. A good agreement between the proposed model and the simulator data was achieved.
Źródło:: Archives of Thermodynamics; 2013, 34, 3; 75-88
1231-0956
2083-6023
Pojawia się w:: Archives of Thermodynamics
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 9.

Tytuł:: Estimation of a tube diameter in a ‘church window’ condenser based on entropy generation minimization
Autorzy:: Laskowski, R.
Rusowicz, A.
Grzebielec, A.
Powiązania:: https://bibliotekanauki.pl/articles/240523.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: entropy generation minimization
power plant condenser
tube diameter
minimalizacja entropii generacji
skraplacz energetyczny
średnica rurek
Opis:: The internal diameter of a tube in a ‘church window’ condenser was estimated using an entropy generation minimization approach. The adopted model took into account the entropy generation due to heat transfer and flow resistance from the cooling-water side. Calculations were performed considering two equations for the flow resistance coefficient for four different roughness values of a condenser tube. Following the analysis, the internal diameter of the tube was obtained in the range of 17.5 mm to 20 mm (the current internal diameter of the condenser tube is 22 mm). The calculated diameter depends on and is positively related to the roughness assumed in the model.
Źródło:: Archives of Thermodynamics; 2015, 36, 3; 49-59
1231-0956
2083-6023
Pojawia się w:: Archives of Thermodynamics
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 10.

Tytuł:: Experimental Study On Thermal Wave Type Adsorption Refrigeration System Working On A Pair Of Activated Carbon And Methanol
Autorzy:: Grzebielec, A.
Rusowicz, A.
Laskowski, R.
Powiązania:: https://bibliotekanauki.pl/articles/185575.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: refrigeration
adsorption system
experimental study
AC-methanol pair
chłodzenie
system adsorpcji
badania eksperymentalne
Opis:: The aim of the study was to examine the efficiency of the thermal wave type adsorption refrigerating equipment working on a pair of activated carbon and methanol. Adsorption units can work in trigeneration systems and in applications driven by waste heat. They can be built also as a part of hybrid sorption-compressor systems, and they are very popular in solar refrigeration systems and energy storage units. The device examined in this study operates in a special mode called thermal wave. This mode allows to achieve higher efficiency rates than the normal mode of operation, as a significant contributor to transport heat from one to the other adsorber. To carry out the experiment a test bench was built, consisting of two cylindrical adsorbers filled with activated carbon, condenser, evaporator, oil heater and two oil coolers. Thermal oil circulation was responsible for providing and receiving heat from adsorbers. In order to perform the correct action a special control algorithm device was developed and implemented to keep the temperature in the evaporator at a preset level. The experimental results show the operating parameters changes in both adsorbers. Obtained COP (coefficient of performance) for the cycle was 0.13.
Źródło:: Chemical and Process Engineering; 2015, 36, 4; 395--404
0208-6425
2300-1925
Pojawia się w:: Chemical and Process Engineering
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 11.

Tytuł:: Ocena stanu retencji zlewni lesnych
Autorzy:: Ciepielowski, A.
Laskowski, R.
Stolarek, A.
Powiązania:: https://bibliotekanauki.pl/articles/969185.pdf
Data publikacji:: 2001
Wydawca:: Instytut Badawczy Leśnictwa
Tematy:: zlewnie lesne
retencja wodna
lesnictwo
Źródło:: Prace Instytutu Badawczego Leśnictwa. Seria A; 2001, 4[923-925]; 5-22
0369-9870
Pojawia się w:: Prace Instytutu Badawczego Leśnictwa. Seria A
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 12.

Tytuł:: Entropy generation in a condenser and related correlations
Autorzy:: Laskowski, R.
Jaworski, M.
Smyk, A.
Powiązania:: https://bibliotekanauki.pl/articles/240683.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: steam condenser
entropy generation
kondensator pary
generowanie entropii
Opis:: The paper presents an analysis of relations describing entropy generation in a condenser of a steam unit. Connections between entropy generation, condenser ratio, and heat exchanger effectiveness, as well as relations implied by them are shown. Theoretical considerations allowed to determine limits of individual parameters which describe the condenser operation. Various relations for average temperature of the cold fluid were compared. All the proposed relations were verified against data obtained using a simulator and actual measurement data from a 200 MW unit condenser. Based on data from a simulator it was examined how the sum of entropy rates, steam condenser effectiveness, terminal temperature difference and condenser ratio vary with the change in the inlet cooling water temperature, mass flow rate of steam and the cooling water mass flow rate.
Źródło:: Archives of Thermodynamics; 2015, 36, 2; 27-48
1231-0956
2083-6023
Pojawia się w:: Archives of Thermodynamics
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 13.

Tytuł:: Experimental investigation of single-phase microjet cooling of microelectronics
Autorzy:: Rusowicz, A.
Leszczyński, M.
Grzebielec, A.
Laskowski, R.
Powiązania:: https://bibliotekanauki.pl/articles/240614.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: cooling
heat transfer
microjets
microprocessor
chłodzenie
wymiana ciepła
mikrojety
mikroprocesor
Opis:: Development of electronics, which aims to improve the functionality of electronic devices, aims at increasing the packing of transistors in a chip and boosting clock speed (the number of elementary operations per second). While pursuing this objective, one encounters the growing problem of thermal nature. Each switching of the logic state at the elementary level of an integrated circuit is associated with the generation of heat. Due to a large number of transistors and high clock speeds, higher heat flux is emitted by the microprocessor to a level where the component needs to be intensively cooled, or otherwise it will become overheated. This paper presents the cooling of microelectronic components using microjets.
Źródło:: Archives of Thermodynamics; 2015, 36, 3; 139-147
1231-0956
2083-6023
Pojawia się w:: Archives of Thermodynamics
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 14.

Tytuł:: Ocena konstrukcji skraplacza na podstawie minimum strumienia generacji entropii
The condenser design assessment on the basis of the minimum entropy generation
Autorzy:: Laskowski, R.
Rusowicz, A.
Grzebielec, A.
Jaworski, M.
Powiązania:: https://bibliotekanauki.pl/articles/271317.pdf
Data publikacji:: 2016
Wydawca:: Centralny Ośrodek Badawczo-Rozwojowy Aparatury Badawczej i Dydaktycznej, COBRABiD
Tematy:: skraplacz
minimum generacji strumienia entropii
ocena konstrukcji skraplacza
condenser
minimum entropy generation
condenser design assessment
Opis:: W skraplaczach energetycznych generowane są jedne z największych strat strumienia entropii w instalacji energetycznej. Celowe jest obniżanie tej straty, aby uzyskać poprawę całkowitej sprawności instalacji. W artykule podano warunek dla minimum generacji strumienia entropii, z którego wynika, że minimum to jest osiągnięte, gdy podgrzew wody w rurkach skraplacza ma równomierny rozkład (przyjmuje taką samą wartość dla wszystkich rurek). Poprawność tego warunku sprawdzono na podstawie danych uzyskanych z symulatora 2D skraplacza dla jednego z krajowych bloków o mocy 50 MW. Na podstawie otrzymanych z symulatora przyrostów temperatur oraz odpowiadających im ciśnień pary dla 30 rurek dokonano oceny poprawności konstrukcji skraplacza.
The losses in power plants condensers are some of the biggest losses in the entropy generation in whole power plant system. It is advisable to decrease the loss for improving the overall efficiency of the system. The article presents the condition for the minimum entropy generation, which states that the minimum is achieved when the heating of the water in the tubes of the condenser has a uniform distribution (takes the same value for all tubes). The correctness of this condition was verified on the basis of data obtained from the 2D condenser simulator for one of the national units with a 50 MW electric capacity. On the basis of the simulator increases temperatures and steam pressures corresponding to 30 tubes assesses the correctness of the construction of the condenser.
Źródło:: Aparatura Badawcza i Dydaktyczna; 2016, 21, 2; 76-84
2392-1765
Pojawia się w:: Aparatura Badawcza i Dydaktyczna
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 15.

Tytuł:: Possibility of using adsorption refrigeration unit in district heating network
Autorzy:: Grzebielec, A.
Rusowicz, A.
Jaworski, M.
Laskowski, R.
Powiązania:: https://bibliotekanauki.pl/articles/240811.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: refrigeration
adsorption refrigeration
air conditioning
district heating network
chłodzenie
absorpcja
klimatyzacja
sieć ciepłownicza
Opis:: Adsorption refrigeration systems are able to work with heat sources of temperature starting with 50°C. The aim of the article is to determine whether in terms of technical and economic issues adsorption refrigeration equipment can work as elements that produce cold using hot water from the district heating network. For this purpose, examined was the work of the adsorption air conditioning equipment cooperating with drycooler, and the opportunities offered by the district heating network in Warsaw during the summer. It turns out that the efficiency of the adsorption device from the economic perspective is not sufficient for production of cold even during the transitional period. The main problem is not the low temperature of the water supply, but the large difference between the coefficients of performance, COPs, of adsorption device and a traditional compressor air conditioning unit. When outside air temperature is 25°C, the COP of the compressor type reaches a value of 4.49, whereas that of the adsorption device in the same conditions is 0.14. The ratio of the COPs is 32. At the same time ratio between the price of 1 kWh of electric power and 1 kWh of heat is only 2.85. Adsorption refrigeration equipment to be able to compete with compressor devices, should feature COPads efficiency to be greater than 1.52. At such a low driving temperature and even changing the drycooler into the evaporative cooler it is not currently possible to achieve.
Źródło:: Archives of Thermodynamics; 2015, 36, 3; 15-24
1231-0956
2083-6023
Pojawia się w:: Archives of Thermodynamics
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 16.

Tytuł:: Application of FMEA in the Quality Estimation of Metal Matrix Composite Castings Produced by Squeeze Infiltration
Autorzy:: Gawdzińska, K.
Chybowski, L.
Przetakiewicz, W.
Laskowski, R.
Powiązania:: https://bibliotekanauki.pl/articles/353212.pdf
Data publikacji:: 2017
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: quality
casting
metal matrix composites
MMC
failure modes and effects analysis
FMEA
material defects
failures
Opis:: Metal matrix composites (MMCs) are still scarcely described due to various combinations of used materials and a wide array of technologies. Applying the Failure Mode and Effect Analysis (FMEA) method to describe the quality of metal composite castings may contribute to eliminating specific (characteristic only to these materials) defects. This part of the analysis determines the criticality numbers, meaning the frequency of a given failure, detectability level and significance of a given failure to the group of specific composite casting failures. It contributes to establishing the priority number (P), which is a measure used to assess risk, a notion essential in discussing quality in a composite casting.
Źródło:: Archives of Metallurgy and Materials; 2017, 62, 4; 2171-2182
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 17.

Tytuł:: Short- and medium-range order in bismuth-silicate glasses: a solecular dynamics study
Autorzy:: Witkowska, A.
Rybicki, J.
Laskowski, R.
Mancini, G.
Feliziani, S.
Alda, W.
Powiązania:: https://bibliotekanauki.pl/articles/1954531.pdf
Data publikacji:: 1999
Wydawca:: Politechnika Gdańska
Tematy:: structure of matter
oxide glasses
MD simulations
Opis:: We report on the results of classical molecular dynamics (MD) simulations of str ucture of amorphous 15 Bi2O3 85 SiO2 [% mol] and 40 Bi2O3 60 SiO2 [% mol], and their totally reduced forms, 15 Bi2 85 SiO2 [% mol], and 40 Bi2 60 SiO2 [% mol], respectively. The simulations have been perfo rmed in the isobaric-isoenthalpic ensemble, using a two-body interaction potential. The set of the potential parameters was constructed as a suitable com bination of the parameters which were previously proposed for pure Bi2O3, and SiO2. Both unreduced, and reduced sy stems were initially prepared as well equilibrated hot melts, and then slowly co oled down to 300K. The structural information from the MD simulations was obtained from radial and angular distribution functions, static structural factors, Voronoi polyhedra sta tistics, and ring analysis. The simulation results can be summarised as follows. In unreduced glass with 15% [mol] Bi2O3 contents, the silicon structural units (mainly regular tetrahedra) form continuous network, whereas in 40% [mol] Bi2O3 glass these units are disconnected. In both unreduced systems Bi ions have mainly six-fold oxygen co-ordination, and no dominating structural unit can be individuated. However, the distorted bismu th units form a continuous network. In both totally reduced glasses (15% Bi2 85% SiO2, and 40% Bi2 60% SiO2 [% mol]), the silica network is built entirely from corner shari ng SiO4 tetrahedra. The structure of the silica subsystem is similar to that of pure *-SiO2. After the reduction, the Bi-Bi co-ordination significantly increases, whereas the first neighbour distance decreases. Moreover, partial static structural fact ors for Bi-Bi pairs indicate that the medium-range order in reduced glasses exhi bits greater periodicity than in unreduced glasses. Neutral Bi atoms form small clusters within the silica matrix.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1999, 3, 2; 239-254
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki