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Technology of Real-World Analyzers (TAUR) and its practical application

Jung J., Kiełbik R., Hałagan K., Polanowski P., Sikorski A.

Computational Methods in Science and Technology

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2020

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Vol. 26, No. 3

69--75

EN

The article describes the most important details of the project for reconfigurable construction of dedicated electronic machines intended for performing analyses of phenomena that occur in multi-component systems containing at least several million mutually interacting elements. Devices built in the presented technology can be characterized by the use of reconfigurable integrated circuits, spatial construction ensuring scalability, a redundant panel system as well as specially developed data transmission and work control systems. Machines work in a parallel manner and can solve problems in various fields of science and technology by competing with the speed of data processing with the latest supercomputing systems. As an example, we present details of the ARUZ machine containing 26,000 FPGAs, which was made using this technology.

2

Carbon isotopes in wood combustion/pyrolysis products: experimental and molecular simulation approaches

Hercman Helena, Szczerba Marek, Zawidzki Paweł, Trojan Agata

Geochronometria

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2019

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Vol. 46, no. 1

111--124

EN

A series of laboratory experiments was performed to determine the carbon stable isotopic composition of different combustion/pyrolysis (B/P) products. Variation in the δ13C values of the products was observed, up to 4‰. The differences in the carbon isotopic compositions of the B/P products were dependent on temperature, time and wood type. Comparison of the results for fresh and fossil oak wood suggested that the δ13C differences were the effect of selective decomposition of some wood components during the fossilization process. The temperature dependence of the carbon isotopic composition was linked to variation in the carbon isotopic composition of the main wood components, which each had different levels of thermal stability. Isotopes exchange reactions in between different products can be also considered as possible source of variation of δ13C on temperature. Both these hypotheses were supported by molecular simulations of cellulose and lignin B/P. The results confirm that B/P should be treated as a continuous process, where the results depend on the degree of process development. Natural burning processes are dynamic and burning conditions change rapidly and it is necessary to take care when using combustion products as a paleoenvironmental proxy or as an isotopic characteristic for the identification of source material.

3

From the Dynamic Lattice Liquid Algorithm to the Dedicated Parallel Computer – mDLL Machine

Jung J., Kiełbik R., Rudnicki K., Hałagan K., Polanowski P., Sikorski A.

Computational Methods in Science and Technology

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2018

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Vol. 24, No. 4

235--247

EN

The designing, production and testing of the mDLL machine led to the development of such a structure in which operational cells (e.g. KDLL) were located in the nodes of a three-dimensional torus network and the device was scalable. Thus, the future expansion of this device with additional Printed Circuit Boards (PCB) will not result in lengthened wire connections between Field-Programmable Gate Arrays (FPGA) or slow down the operation of the machine. The conducted tests confirmed the correctness of the adopted design assumptions and showed that by using mDLL one can effectively perform molecular simulations. Despite some structural shortcomings, the mDLL machine was a prototype that has already been sufficiently tested to allow the technology used in it to be used to build a device with a number of 1 million to 5 million KDLL cells. Such a device would already be suitable for simulating multi-particle systems with unprecedented speed.

4

Od algorytmu dynamicznej cieczy sieciowej do dedykowanego komputera równoległego II – maszyna mDLL

Jung J., Kiełbik R., Rudnicki K., Polanowski P.

Przegląd Elektrotechniczny

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2017

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R. 93, nr 11

162--170

PL

W artykule opisano złożenia projektowe, budowę i realizację maszyny przeznaczonej do symulacji zjawisk zachodzących w wieloskładnikowych układach molekularnych. Przedstawiony system elektroniczny zbudowano przy użyciu programowalnych układów scalonych FPGA (w j. ang. Field Programmable Gate Array). W maszynie zaimplementowano model dynamicznej cieczy sieciowej (ang. dynamic lattice liquid - DLL) i wykonano testy jej działania.

EN

The article describes the assumption of design, construction and implementation of a machine intended to simulate the phenomena occurring in complex molecular systems. Presented electronic system was built with the Field Programmable Gate Array (FPGA). In the machine was implemented a model of Dynamic Lattice Liquid (DLL) and the tests of the device operation was performed.

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Mechanical Properties of 2D Flexyne and Reflexyne Polyphenylacetylene Networks: A Comparative Computer Studies with Various Force-Fields

Trapani L., Gatt R., Mizzi L., Grima J. N.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2015

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Vol. 19, No 3

237--296

EN

Auxetic materials exhibit the very unusual property of becoming wider when stretched and narrower when compressed, – they have a negative Poisson’s ratio. This unusual behaviour is the source of many desired effects in the materials’ properties and it is therefore, no wonder that auxetics are described as being superior to conventional materials in many practical applications. Here we make use of force-field based molecular modelling simulations in order to investigate the mechanical properties of polypehyleacetylene systems known as (n, m)-flexyne and (n, m)-reflexyne in an attempt to extend the existing knowledge there is regarding these systems. These systems have already attracted considerable consideration since negative on-axis Poisson’s ratios have been discovered for the reflexynes. We first developed a methodology for the modelling and property determination of flexyne and reflexyne network systems which we validated against existing published data. Then, extended the study to prove the simulated results were independent of the modelling methodology or the force-field used. In particular, we showed that on-axis auxeticity in the reflexynes is a force-field independent property, i.e. a property which is not an artefact of the simulations but a property which is likely to be present in the real materials if these were to be synthesised. We also studied and reported the shear behaviour of these systems were we show that the flexynes and reflexynes have very low shear moduli, a property which regrettably limits the prospects of these systems in many practical applications. Finally we examine the in-plane off-axis mechanical properties of the systems and we report that in general, these mechanical properties are highly dependent on the direction of loading. We also find that the auxeticity exhibited by the reflexynes on-axis is lost when these systems are loaded off axis since the Poisson’s ratios becomes positive very rapidly as the structure is stretched slightly off-axis (e.g. 15deg off-axis). This is once again of great practical significance as it highlights another major limitation of these systems in their use as auxetics.

6

Material Storage Mechanism in Porous Nanocarbon - Comparison between Experiment and Simulation

Terzyk A. P., Gauden P. A., Furmaniak S., Kowalczyk P.

Computational Methods in Science and Technology

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2012

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Vol. 18, No. 1

45-51

EN

We present first MD simulation results of C60 adsorption inside a single-walled carbon nanohorn. The assumed carbon nanohorn model and the values of the force field parameters lead to relatively good agreement between simulation and experiment. We show that the confinement of water and ethanol inside a carbon nanohorn strongly changes the properties of confined liquids leading to a decrease in the number of hydrogen bonds, and diffusion coefficients in comparison to bulk. The appearance of C60 inside the nanohorn leads to further decrease in diffusion coefficients of confined solvents.

7

Performance, Sensitivity and Non-covalent Hydrogen Bonds of Explosives

Pospíši M., Vávra P.

Central European Journal of Energetic Materials

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2007

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Vol. 4, nr 3

25-32

EN

A set of 30 different molecular structures generally confirms that the sensitivity usually increases with increasing the value of detonation energy. This can be influenced by several factors depending on the type of crystal structure and on the properties depending on mutual interactions among the molecules in the crystal. In this work, the influence of hydrogen bond interactions on decreasing sensitivity of energetic materials was especially confirmed in cases where amine head group is a donor of proton. The knowledge of basic crystal structure properties relationship in detail may allow to predict new structures of energetic materials with low sensitivity and high detonation energy per unit volume by molecular simulation methods.

8

Numerical simulation of atomic positions in quantum dot by means of molecular statics

Dłużewski P., Traczykowski P.

Archives of Mechanics

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2003

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Vol. 55, nr 5-6

393-406

EN

Deformation of a crystal structure is considered here in terms of constitutive modelling based upon both the atomistic and continuum approaches. Atomistic calculations are made by using the Stillinger-Weber potential for the GaAs and CdTe structures. The stress-strain behaviour of the best-known anisotropic hyperelastic models are compared with the behaviour of the atomistic one in the uniaxial deformation test.

9

The Influence of low density behaviour of state equation on lattice inverted pair potential for lead

Laskowski R., Chybicki M.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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1999

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Vol. 3, No 3

303-312

EN

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.