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1

Analiza składu kopolimeru na podstawie symulacji małych układów reakcyjnych

Lechowicz Jaromir B.

Polimery

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2022

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Vol. 67, nr 1

13--19

PL

Metodą symulacji Monte Carlo zbadano przebieg gradientowej kopolimeryzacji monomerów dwufunkcyjnych. Skład kopolimeru wyznaczono poprzez uśrednienie składu kolejnych segmentów łańcuchów makrocząsteczek. Zmiana wielkości segmentów pozwoliła na oszacowanie profilu gradientu składu małych układów reakcyjnych. Zastosowana procedura nie wymaga dużego nakładu obliczeniowego.

EN

The course of gradient copolymerization of bifunctional monomers was investigated using the Monte Carlo simulation method. The copolymer composition was determined by averaging the composition of successive segments of macromolecular chains. Changing the size of the segments made it possible to estimate the gradient profile of the composition of small reaction systems. The applied procedure does not require a large computing system.

2

Modelowanie procesu kopolimeryzacji przemiennej cyklicznych bezwodników z epoksydami

Lechowicz Jaromir B.

Polimery

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2019

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T. 64, nr 4

252--258

PL

Modelowano proces katalitycznej kopolimeryzacji przemiennej z otwarciem pierścienia bezwodników z epoksydami. Opracowano model teoretyczny, uwzględniający etapy procesu: inicjowanie, propagację i wybrane reakcje uboczne. Wykonano symulacje układów reakcyjnych różniących się udziałem katalizatora. Badano wpływ czynników kinetycznych na powstawanie wiązań eterowych i wartość ciężaru cząsteczkowego produktu. Przebadano też efekty inicjowania układu reakcyjnego kwasem dikarboksylowym obecnym zwykle w bezwodniku. Stwierdzono wyraźny wpływ wszystkich badanych czynników na przebieg symulowanego procesu. Największe ciężary cząsteczkowe wykazywały produkty uzyskane przy możliwie dużym stosunku molowym monomerów do katalizatora i maksymalnie oczyszczonych substratach oraz wysoce selektywnych katalizatorach, co ograniczało możliwość wystąpienia reakcji ubocznych.

EN

Catalyst-assisted alternating ring-opening copolymerization of anhydrides and epoxides was modeled. A theoretical model was developed, which included initiation, propagation and side reactions. Simulations of reactions systems with different catalyst contents were performed. The effect of kinetic parameters on the formation of ether links and the resulting molecular weight of the polymer product was studied using Monte Carlo methods. Also, the effect of initiation of the reacting system by dicarboxylic acid usually present in the anhydride was investigated. It was found, that all the examined factors influenced the simulated polymerization process. The highest molecular weight of the polymer can be obtained at the highest molar ratio of monomers to catalyst, using carefully purified substrates and highly selective catalysts, thereby limiting the side reactions.

3

The impact of a non-uniform land surface on the radiation environment over an Arctic fjord - a study with a 3D radiative transfer model for stratus clouds over the Hornsund fjord, Spitsbergen

Rozwadowska A., Górecka I.

Oceanologia

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2012

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No. 54 (4)

509-544

EN

This paper estimates the influence of land topography and cover on 3D radiative effects under overcast skies in the Arctic coastal environment, in particular in the Hornsund fjord region, Spitsbergen. The authors focus on the impact of a non-uniform surface on: (1) the spatial distribution of solar fluxes reaching the fjord surface, (2) spectral shortwave cloud radiative forcing at the fjord surface, (3) the solar flux anomaly at the domain surface resulting from the assumption of a uniform surface, i.e. the error due to plane parallel assumptions in climate models, and (4) remote sensing of cloud optical thickness over the fjord. Their dependence on spectral channel, cloud optical thickness, cloud type, cloud base height, surface albedo and solar zenith angle is discussed. The analysis is based on Monte Carlo simulations of solar radiation transfer over a heterogeneous surface for selected channels of the MODIS radiometer. The simulations showed a considerable impact of the land surrounding the fjord on the solar radiation over the fjord. The biggest differences between atmospheric transmittances over the fjord surface and over the ocean were found for a cloud optical thickness τ = 12, low solar zenith angle υ, high cloud base and snow-covered land. For τ= 12, υ = 53°, cloud base height 1.8 km and wavelength λ= 469 nm, the enhancement in irradiance transmittance over the fjord was 0.19 for the inner fjords and 0.10 for the whole fjord (λ = 469 nm). The land surrounding the Hornsund fjord also had a considerable impact on the spectral cloud radiative forcing on the fjord surface and the solar flux anomaly at the domain surface due to the uniform surface assumption. For the mouth and central part of the fjord the error due to the use of channel 2 of the MODIS radiometer (λ = 858 nm) for cloud optical thickness retrieval was < 1 in the case of low-level clouds (cloud base height 1 km, nadir radiance, υ = 53°, cloud optical thickness retrieved solely from MODIS channel 2). However, near the shoreline (up to 2 km from it), especially over the inner fjords, the cloud optical thickness was then overestimated by > 3 for τ = 5 and by > 5 for τ = 20.

4

The ways of effective estimation of measurand

Galovska M., Warsza Z. L.

Pomiary, Automatyka, Komputery w Gospodarce i Ochronie Środowiska

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2010

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nr 1

18-20

EN

The main purpose of this work is the expansion of the ways for choosing the best estimator of empirical data, when this data is only available information. Proposed methods are divided into two groups: Monte-Carlo simulation and resampling methods. Numerical example is given.

PL

Podstawowym celem pracy jest rozszerzenie sposobów wyboru estymatora danych empirycznych, gdy dane te są jedyną dostępną informacją. Proponowane metody podzielono na 2 grupy: oparte na symulacji Monte Carlo i na metodach "resamplingu". Zilustrowano to przykładem liczbowym.

5

Ocean optics in application to remote detection of an oil-in-water emulsion originating from the engine room

Otremba Z., Rudź K.

Journal of KONES

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2010

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Vol. 17, No. 3

349-353

EN

Relatively great number of detected and confirmed oil spillages in the Polish marine areas reveals that discharge of oil substances from any one of a large number of ships to the marine environment is real in any time. Surface oil contamination can be easily detected by satellite or airborne radar techniąues, but unfortunately oil dispersed in the bulk of water cannot be detected at the present. Discharge waters usually contain small amounts ofoil substances in the form of dispersed droplets (emulsion). It is revealed that oil emulsion cause measurable changes in the optical properties of seawater. In practice, detection of changes of these properties should be possible by the standard radiance or irradiance reflectance meter. This paper presents a computed photon trace simulation applied to the marine environment polluted by oil-in-water emulsion. Model of marine area consists ofwhether conditions, sun elevation, sea depth, optical properties of seawater related to various transparency/turbidity: from clean oceanic waters to turbid coastal seawater (as water from Gulf of Gdańsk is). Model of oil pollution is represented by oil droplets size distribution and by spectra of both attenuation-coefficient and refraction-coefficient related to two optically absolutely different kinds of oil. It is revealed that the values of irradiance reflectance are significantly differ for the clean sea area in relation to the polluted one, even for small amounts of engine-room origin oil pollution.

6

Modelling of charge carrier transport in conjugated polymers doped by polar additives

Toman P., Nešpůrek S., Bartkowiak W.

Materials Science Poland

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2009

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Vol. 27, No. 3

797--812

EN

A theoretical model of the inter-chain charge carrier transport in poly[2-methoxy-5-(2´-ethylhexyloxy)- p-phenylene vinylene] doped with a photochromic polar additive is put forward. The model attributes to each polymer chain a set of charge states, in which charge carriers thermalize. These on-chain states are calculated by solving the Schrodinger equation with a tight binding Hamiltonian. The interchain transfer rates are determined using the Marcus formula. The model describes the effect of polar additives on charge carrier transport. The presence of the additives results in a decrease of charge mobility, because of the increase of the local energy disorder. A decrease of the inter-chain mobility by up to several orders of magnitude is found if the width of the local energy disorder is doubled. This finding confirms the possibility of constructing an optoelectrical switch based on a polymer doped with a photochromic polar additive.

7

A Monte Carlo model of hyperbranched polymerization

Galina H., Lechowicz J. B.

Polimery

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2001

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T. 46, nr 11-12

840-843

EN

A Monte Carlo computer model of is described for hyperbranched polymerization involving AB2 monomers. The structure of algorithm used in the model and selected results of its application are presented. The results are compared with those obtained by using an analytical kinetic model. For analogous polymerization systems, the two models were found to yield identical molecular parameters, viz., the average degrees of polymerization as the degree of conversion was varied, and polydispersity index for the reacting systems involving different substitution effects.

PL

Przedstawiono komputerowy model polimeryzacji hiperrozgałęzionej monomeru AB2 wykorzystujący metodę Monte Carlo. Opisano strukturę algorytmu zastosowanego w modelu i podano niektóre wyniki jego stosowania, porównując je z wynikami uzyskanymi za pomocą kinetycznej metody modelowania. Parametry molekularne, obliczone w odniesieniu do analogicznych układów polimeryzacyjnych przy użyciu obydwu modeli są takie same. Takie same są obliczone średnie stopnie polimeryzacji i ich zmiany ze stopniem przereagowania grup funkcyjnych (rys. 2), a także jednakowe są wskaźniki polidyspersyjności obliczone w przypadku układów reagujących z różnymi efektami podstawienia.