Nauki Techniczne

Bulletin of the Polish Academy of Sciences: Technical Sciences

Zawartość

Bulletin of the Polish Academy of Sciences: Technical Sciences | 2013 | 61 | No 2 |

Abstrakt

Abstract The paper shows that symmetry forms a basis for relations between different properties of material. In this way, the key quantities for specification of an atomistic model are identified. Material symmetry distinguishes representative processes of small strains. It is proved that the errors in the densities of the energies stored in these processes determine the range of inaccuracies with which an atomistic model recreates processes of small deformations. The errors are equal to the inaccuracies in the eigenvalues of the elasticity tensor, that is in the Kelvin moduli. For cubic crystals, the elementary processes indicated by the symmetry initiate the key paths of large deformations: Bain and trigonal ones. Therefore, the substantial errors in the Kelvin moduli lead to incorrect reconstructing the metastable phases: bcc, sc and bct. The elastic constants commonly used in the literature do not provide such information as the Kelvin moduli. Using the eigenvalues of the elasticity tensor as well as other key properties indicated by the symmetry, the EAM model proposed by A.F. Voter for copper is specified. The obtained potential more accurately reproduces small and large deformations and additionally, correctly describes defect formation as well as Cu dimer properties
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Autorzy i Afiliacje

K. Nalepka

Abstrakt

Abstract The paper presents numerical analyses aimed at preliminary assessment of the protective panel effectiveness, which task is to protect the elements of building structures against explosion. For the criterion of assessing the effectiveness of the panel the load capacity of the column made of steel I-beam was chosen. Ultimate force was determined by using advanced computational procedure, which consisted of four stages: preload, blast simulation, dynamic response and static analysis of deformed structure. Blast load was simulated using Lagrangian- Eulerian domain coupling. Results indicated that the application of the protective panel significantly reduces the plastic deformation of the structure.
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Autorzy i Afiliacje

L. Mazurkiewicz
J. Malachowski
D. Kołodziejczyk
K. Damaziak
M. Klasztorny
P. Baranowski

Abstrakt

Abstract Computed tomography is one of the most significant diagnostic techniques in medicine. This work is focused on hard-field imaging, where signals take a form of straight rays and the reconstructed image can be presented as a matrix with unknown pixels. Algebraic methods for direct computation of the image have not been used in practice because of the scale of the problem and numerical errors appearing in the solution. The aim of this work was to analyse the performance of direct algebraic algorithms for tomographic image reconstruction including regularisation mechanism such as: generalised regularisation, Tikhonov regularisation, Twomey regularisation and ridge regression (RR), as well as comparing the results with the filtered backprojection (FBP) as the reference method. The performed analyses demonstrated that the regularised algebraic methods are more accurate than the commonly used FBP, and RR appeared the most precise among them. Additionally it was shown that the invariant system matrix (inverted during calculations) can be easily determined by solving the forward problem. Finally, potential directions of further research have been pointed out.
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Autorzy i Afiliacje

D. Wysoczański
J. Mroczka
A.G. Polak

Abstrakt

Abstract The contents are concerned with a concept of an oilless and frictionless compressor operating without dead movement and having functional parameters superior to compressors of renowned manufacturers. The concept is based on patents No. 68220, 83060, P377851 by W. Chomczyk and patents P394072, P385733 by W. Chomczyk, W. Ostapski and J. Piotrowski. The proposed design of an oilless compressor ensures volumetric efficiency higher than that encountered in conventional compressors. It also generates pure compressed medium without necessity of filtering from oil particles, which is especially desired in food, pharmaceutical, medical, fragrance, chemical and automation industry.
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Autorzy i Afiliacje

W. Chomczyk
J. Piotrowski
W. Ostapski
T. Tataj

Abstrakt

Abstract Copper-based composites could be widely used in automotive, electronic or electrical industry due to their very promising thermal properties. In the present paper, Cu-AlN metal matrix composites with ceramic volume fractions between 0.1 and 0.4 were fabricated by hot pressing method in vacuum. Dependence of the coefficient of thermal expansion (CTE) and the thermal conductivity (TC) on the chemical composition of composites has been investigated. The measured values of the thermal expansion coefficient have been compared with the analytical models’ predictions. A numerical model based on FEAP 7.5 in 3D space has been used to evaluate the influence of the porosity on the thermal properties (thermal conductivity) of the composite. A fairly good correlation between the FEM results and the experimental measurements has been obtained.
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Autorzy i Afiliacje

M. Chmielewski
W. Weglewski

Redakcja

Editorial Board 2020-2022

Editor-in-Chief:

M.P. Kazmierkowski, Warsaw University of Technology

Honorary (Past) Editor-in Chief:

T. Kaczorek, Warsaw University of Technology

Deputy Editor-in-Chief:

A. Rogalski, Division IV Technical Sciences PAN

B. Błachowski, Institute of Fundamental Technological Research PAN

Board of Topical Co-editors:

Artificial and Computational Intelligence

S. Osowski and B. Sawicki, Warsaw University of Technology

Biomedical Engineering and Biotechnology

A. Liebert, Institute of Biocybernetics and Biomedical Engineering PAN

Civil Engineering

L. Czarnecki, Building Research Institute, ITB, Warsaw

Control, Robotics and Informatics

J. Klamka and A. Babiarz, Silesian Technical University

A. Borkowski, Institute of Fundamental Technological Research PAN

Electronics, Telecommunication and Optoelectronics

M. Mrozowski and A. Lamęcki, Gdansk University of Technology

Mechanical and Aeronautical Engineering, Thermodynamics

B. Błachowski and P. Korczyk, Institute of Fundamental Technological Research PAN

A. Tylikowski, Lukasiewicz Research Network - Institute of Mechanised Construction and Rock Mining, Warsaw

Materials Science and Nanotechnology

B. Major and P. Czaja, Institute of Metallurgy and Materials Science PAN

Power Systems and Power Electronics

M.P. Kazmierkowski, Warsaw University of Technology

International Editorial Advisory Board

R. Asthana, University of Wisconsin-Stout, Menomonie, USA

Xu Binshi, China Association of Plant Engineering, Beijing, P.R. China

F. Blaabjerg, Aalborg University, Denmark

C. Cecati, University of L’Aquila, Italy

A. Cichocki, RIKEN Institute, Tokyo, Japan

M. David, National Polytechnique de Toulouse, France

R. Ebner, Materials Centre Leoben, Leoben, Austria

E. Fornasini, University of Padova, Padova, Italy

L.G. Franquelo, University of Sevilla, Spain

M. Gad-el-Hak, Virginia Commonwealth University, Richmond, USA

M. Giersig, Free University of Berlin, Germany

D. van Gemert, Catholic University Leuven, KU Leuven, Belgium

L. Keviczky, Hungarian Academy of Sciences, Budapest, Hungary

V. Kučera, Czech Technical University in Prague, Prague, Czech Republic

R. Kennel, Technical University Munich, Germany

T.A. Kowalewski, Institute of Fundamental Technological Research PAN

E. Levi, Liverpool John Moore University, UK

G. Maier, Technical University of Milan, Milan, Italy

K.F. Man, City University of Hong Kong,

R. Maniewski, Institute of Biocybernetics and Biomedical Engineering PAN

H.A. Mang, Austrian Academy of Sciences, Vienna, Austria

H. Mihashi, Tohoku University, Aoba-ku, Sendai, Japan

S. Mindess, University of British Columbia, Vancouver, Canada

D.A. Mlynski, University of Karlsruhe, Karlsruhe, Germany

A.S. Nowak, University of Michigan, Ann Arbor, USA

K. Ohnishi, Keio University, Yokohama, Japan

A. Öberg, Linköping University, Linköping, Sweden

W. Pedrycz, University of Alberta, Canada

S. Przemieniecki, University of South Florida, Tampa, USA

M. Razeghi, Northwestern University, Evanston, USA

J. Rodriguez, University of Andres Bello, Santiago, Chile

J.V. Sloten, Catholic University Leuven, Leuven, Belgium

B.M. Wilamowski, University of Auburn, Alabama, USA

W. Włosiński , Warsaw University of Technology, Warsaw, Poland

A.L. Yarin, University of Illinois at Chicago, USA

Du Xiangwan, Chinese Academy of Engineering, China

J. Żurada, Department of Computer Engineering, University of Louisville, USA

Kontakt

Editorial Office:

Pałac Kultury i Nauki

Wydział IV Nauk Technicznych PAN

Pl. Defilad 1

PL 00-901 Warszawa

Copy Editor:

Renata Podraza, e-mail: renata.podraza@pan.pl

Finance:

Ewa Trojanowska, ewa.trojanowska@pan.pl

Instrukcje dla autorów

Polityka Open Access

Bulletin of the Polish Academy of Sciences: Technical Sciences jest czasopismem wydawanym w wolnym dostępie na licencji CC BY-NC-ND 4.0.

Bulletin of the Polish Academy of Sciences: Technical Sciences is an open access journal with all content available with no charge in full text version. The journal content is available under the licencse CC BY-NC-ND 4.0.

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