Rzeszow University of Technology

Rzeszow, Poland
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Rzeszow University of Technology | Date: 2017-03-08

Thermoplastic wood filler which is a polymer composite including a filling agent dispersed in a polymer matrix which is in the form of copolymer of polyethylene and poly(vinyl acetate), and the filling agent is either a mixture of calcium carbonate and silica or alumina. In addition it is favourable to add mineral oil in the quantity from 3 to 20 % of mass, and in particular 3 % of mass and pigment in the form of powder, in the quantity up to 3 % of mass, and in particular 1 % of mass. The share of the filling agent in the polymer matrix is from 50 to 80 % of mass, favourably from 50 to 65 % of mass of calcium carbonate and from 5 to 20 % of mass of silica with commercial name N 0.1-0.3, or 50 % of mass of alumina. The way of production of the composite is characterised in that in the first stage the mixture of polymer matrix, non-organic filling agents, mineral oil and pigment is homogenised, and in the second stage the homogeneous mixture is embossed in an extruder with the reservation that it is favourable to use the one- or two-screw extruder.

Wiktorowicz K.,Rzeszow University of Technology
IEEE Transactions on Fuzzy Systems | Year: 2017

This paper proposes a design method for secondorder systems that guarantees the stability of an adaptive fuzzy controller with state feedback. The system consists of a linear unstable plant, the Takagi-Sugeno controller, a nonlinear reference model, and an adaptationmechanism. In this paper, gradient-based adaptation is used to change the consequents of the controller rules so that the closed-loop system behaves like the reference model. The proposed method utilizes a frequency-domain criterion in the form of the modified circle theorem. The controller function is assumed to be a nonlinearity described by a sector condition, which means that the function lies between two planes. During the process of adaptation, this function is verified so it stays in the sector guaranteeing stability. The method described here is illustrated by an example of a control system containing an unstable plant with an unknown pole in the right half-plane. The motivation of this paper is to propose a frequency-domain method for the design of state feedback adaptive fuzzy controllers. Comparing with time-domain methods that require advanced software tools, the proposed method offers simple graphical interpretation on the Nyquist plane. © 2016 IEEE.

Blocked polyisocyanate crosslinkers for powder coatings were synthesized using alicyclic diisocyanates (TMDI and IPDI), formic acid, (methylaminopropyl) hepta(isobutyl)Si 8O 12 (POSS), ε-caprolactam, dibutyltin dilaurate as well as triethylamine as catalysts. The chemical structures of these compounds were characterized by means of IR, 1H NMR and 13C NMR spectroscopy. The three-dimensional surface topography and surface chemical structure of the resulting powder coatings were investigated by using confocal microscope and ATR FT-IR. The values of surface roughness parameters were calculated. The surface topography was correlated with the chemical structure of the coatings and macroscopic surface behaviour: surface free energy, abrasion resistance, hardness, adhesion to the steel surface and impact resistance. Thermogravimetric analysis was employed to assess the hardening property of powder coatings and the thermal decomposition processes. © 2012 Elsevier B.V.

This paper analyzes the shearing strength analysis of single-lap joints made by self-pierce riveting with a solid rivet for various joining parameters.The sheet metal joining with various pressure force while joining with the universal rivet. The shearing tests were performed for such prepared overlap joint specimens.The capabilities of joining various material with the solid rivet with conventional tool movement solutions were presented. The strength tests were based on the uniaxial shearing test of folded joints and single-side tearing test of L-specimens. The shearing test specimens were made of various thickness arrangements from 1.0. mm to 2.5. mm and materials as steel DC01, H320LA, H400LA, aluminum alloys 5754, 5556, and stainless steel X2CrNi12, X5CrNi18-10, too.The experiments were complemented with the FEM simulation in order to track the effect of rivet type on residual stress level. The FEM simulation was also performed for different pressure edge width values in order to observe the lower sheet material plastifying. © 2013 Elsevier Ltd.

Kaczmarski K.,Rzeszow University of Technology
Journal of Chromatography A | Year: 2011

Packed chromatographic columns with the superficially porous particles (porous shell particles) guarantee higher efficiency. The theoretical equation of the Height Equivalent to a Theoretical Plate (HETP), for columns packed with spherical superficially porous particles, was used for the analysis of the column efficiency for finite rate of adsorption-desorption process. The HETP equation was calculated by the application of the moment analysis to elution peaks evaluated with the General Rate (GR) model. The optimal solid core radius for maximum column efficiency was estimated for a wide spectrum of internal and external mass transfer resistances, adsorption kinetic rate and axial dispersion. The separation power of the shell adsorbent for two component mixture, in analytical and preparative chromatography, was discussed. The conditions of the equivalence between the solutions of the General Rate model with slow adsorption kinetic and the Lumped Kinetic Model (LKM) or the Equilibrium Dispersive (ED) model were formulated. © 2010 Elsevier B.V.

Jezzowski J.,Rzeszow University of Technology
Industrial and Engineering Chemistry Research | Year: 2010

The designing of heat exchanger networks (HENs), mass exchanger networks (MENs), and water networks (WNs) is a major topic of process system engineering. The WN problem is most recent, and although the seminal work was published in 1980, the real development should be dated from 1994. Increasing public concern on scarce water resources, together with stringent regulations on wastewater discharge, has caused a great number of publications in recent years. Despite noticeable achievements in the topic, there is still a need for robust flexible approaches that will find wider application in practice. This review provides the reader with literature annotations on the WN problem from the year 1980 and follows the format of an earlier HEN review paper [Furman, K. C.; Sahinidis, N. V. A critical revue and annotated bibliography for heat exchanger network synthesis in the 20th century. Ind. Eng. Chem. Res. 2002, 41, 2335-2370]. An analysis of the WN problem formulation also is given, together with an overview of solution techniques. Statistics and classifications of the literature annotations are provided. Finally, thoughts on the direction of future research are presented. © 2010 American Chemical Society.

The formulas are derived that enable calculations of intersubband absorption coefficient within nonequilibrium Green's function method applied to a single-band effective-mass Hamiltonian with the energy dependent effective mass. The derivation provides also the formulas for the virtual valence band components of the two-band Green's functions which can be used for more exact estimation of the density of states and electrons and more reliable treatment of electronic transport in unipolar n-type heterostructure semiconductor devices. © 2015 AIP Publishing LLC.

Linkov A.M.,Rzeszow University of Technology
International Journal of Engineering Science | Year: 2012

Hydraulic fracture has been a subject of many numerical simulations. They usually employed the opening and pressure as unknowns. In this paper, we demonstrate the advantages of using, instead, the particle velocity and the lubrication equation reformulated in its terms. It reduces the problem to finding functions, which are analytical near the fluid front. This overcomes difficulties caused by strong non-linearity of the equations, moving boundary and high stiffness of equations resulting from spatial discretization. The efficiency of the approach is illustrated on the classical problems by Nordgren (1972) and Spence and Sharp (1985). Simple analytical solutions of these problems are obtained. It appears that when leak-off is negligible, the particle velocity is almost constant along the entire flow region what elucidates the conditions of the proppant movement in low permeability rocks. © 2011 Elsevier Ltd. All rights reserved.

Mucha J.,Rzeszow University of Technology
Materials and Design | Year: 2011

In this study, the effect of the process parameters of the clinching process on the joinability of advanced high-strength steel was investigated using finite element analysis (FEA). The effect of die geometrical parameters on the achieved joint lock size and maximum forming force has been determined. It has been determined that the die groove width is the most important parameter affecting the material flow effect and energy consumption of the joining process. From the result, the die radius, die depth, and die groove shape were mainly affected by the joinability of advanced high-strength steel H320LA. The results of experiments and numerical tests enable determining the effective process parameters of H320LA sheet metal joining process. © 2011 Elsevier Ltd.

Romanowska J.,Rzeszow University of Technology
Calphad: Computer Coupling of Phase Diagrams and Thermochemistry | Year: 2014

The aluminum diffusion in aluminide coatings deposited on nickel by the CVD method was investigated. The microstructure, chemical and phase compositions of coatings were examined by SEM, EDS and XRD techniques. The triple zone structure was revealed. The β-NiAl phase was on the surface of the coatings, whereas γ-(Ni) and γ′-Ni3Al formed deeper parts of the coatings. Diffusion coefficients were calculated from the concentration profiles in coatings deposited for various times (15 min, 1 h, 4 h and 8 h) at 1000 C and 1050 C. The procedure was based on the classic finite difference method (FDM). Diffusion coefficients in three phases were calculated simultaneously and the influence of diffusivity in one phase on the diffusivity in the neighboring phase was taken into account. The results of the calculation agree with the literature data obtained for each of the analyzed phases separately. © 2013 Elsevier Ltd.

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