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Politechniki Gdańskiej

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Publikacje z roku 2015

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  • The application of a photopolymer material for the manufacture of machine elements using rapid prototyping techniques
    • Artur Andrearczyk
    2015 Logistyka

    The paper discusses the application of polymer resin for 3D printing. The first section focuses on rapid prototyping technique and properties of the photopolymer, used as input material in the manufacture of machine components. Second part of the article was devoted to exemplary 3-D-printed elements for incorporation in machines. The article also contains detailed description of problems encountered in implementation of the selected rapid prototyping technology and the ways to deal with them.

  • The Backbone Coloring Problem for Bipartite Backbones
    • Robert Janczewski
    • Krzysztof Turowski
    2015 GRAPHS AND COMBINATORICS

    Let G be a simple graph, H be its spanning subgraph and λ≥2 be an integer. By a λ -backbone coloring of G with backbone H we mean any function c that assigns positive integers to vertices of G in such a way that |c(u)−c(v)|≥1 for each edge uv∈E(G) and |c(u)−c(v)|≥λ for each edge uv∈E(H) . The λ -backbone chromatic number BBCλ(G,H) is the smallest integer k such that there exists a λ -backbone coloring c of G with backbone H satisfying maxc(V(G))=k . A λ -backbone coloring c of G with backbone H is optimal if and only if maxc(V(G))=BBCλ(G,H) . In the paper we study the problem of finding optimal λ -backbone colorings of complete graphs with bipartite backbones. We present a linear algorithm that is 2 -approximate in general and 1.5 -approximate if backbone is connected. Next we show a quadratic algorithm for backbones being trees that finds optimal λ -backbone colorings provided λ is large enough.

  • The bahaviour of selected silver coated body implants in presence of various bacteria
    • Beata Świeczko-Żurek
    • Anna Pałubicka
    • Andrzej Zieliński
    2015 SYLWAN

    The article deals with implants covered with silver nanoparticles and its influence on bacteria adhesion.

  • The cohomological span of LS-Conley index
    • Jakub Maksymiuk
    2015 Pełny tekst JOURNAL OF DIFFERENTIAL EQUATIONS

    In this paper we introduce a new homotopy invariant – the cohomological span of LS-Conley index. We prove the theorems on the existence of critical points for a class of strongly indefinite functionals with the gradient of the form Lx+K(x), where L is bounded linear and K is completely continuous. We give examples of Hamiltonian systems for which our methods give better results than the Morse inequalities. We also give a formula for the LS-index of an isolated critical point, which is an extension of the classical Dancer theorem for the case of LS-index.

  • The comparison of vodka, whisky and moonshine by using the electronic nose based on the technology of ultra-fast gas chromatography
    • Paulina Wiśniewska
    • Magdalena Śliwińska
    • Tomasz Dymerski
    • Waldemar Wardencki
    • Jacek Namieśnik
    2015

    Vodka andwhisky are produced fromgrain distillates. Formerly these alcohols were very often counterfeited, by the made in home conditions spirit drink called moonshine, which is obtained by distilling a mash from the alcoholic fermentation. This study presents research aimed at checking the usefulness of the electronic nose using ultra-fast gas chromatography for the differentiation of whisky, vodka and moonshine. 12 samples of different spirits beverages were analyze by Heracles II electronic nose. Data were analyzed by the following chemometric methods: PCA – Principal Component Analysis, DFA Discriminant Function Analysis,SIMCAclassification Soft Independent Modeling of Class Analogies,SQC Statistical Quality Control.

  • The comparison of vodka, whisky and moonshine by using the electronic nose based on the technology of ultra-fast gas chromatography
    • Paulina Wiśniewska
    • Magdalena Śliwińska
    • Tomasz Dymerski
    • Waldemar Wardencki
    • Jacek Namieśnik
    2015

    Vodka andwhisky are produced fromgrain distillates. Formerly these alcohols were very often counterfeited, by the made in home conditions spirit drink called moonshine, which is obtained by distilling a mash from the alcoholic fermentation. This study presents research aimed at checking the usefulness of the electronic nose using ultra-fast gas chromatography for the differentiation of whisky, vodka and moonshine. 12 samples of different spirits beverages were analyze by Heracles II electronic nose. Data were analyzed by the following chemometric methods: PCA – Principal Component Analysis, DFA Discriminant Function Analysis,SIMCAclassification Soft Independent Modeling of Class Analogies,SQC Statistical Quality Control.

  • The complexity of minimum-length path decompositions
    • Dariusz Dereniowski
    • Wieslaw Kubiak
    • Yori Zwols
    2015 Pełny tekst JOURNAL OF COMPUTER AND SYSTEM SCIENCES

    We consider a bi-criteria generalization of the pathwidth problem, where, for given integers k, l and a graph G, we ask whether there exists a path decomposition P of G such that the width of P is at most k and the number of bags in P, i.e., the length of P, is at most l. We provide a complete complexity classification of the problem in terms of k and l for general graphs. Contrary to the original pathwidth problem, which is fixed-parameter tractable with respect to k, we prove that the generalized problem is NP-complete for any fixed k >= 4, and is also NP-complete for any fixed l >= 2. On the other hand, we give a polynomial-time algorithm that, for any (possibly disconnected) graph G and integers k <= 3 and l > 0, constructs a path decomposition of width at most k and length at most l, if any exists. As a by-product, we obtain an almost complete classification of the problem in terms of k and l for connected graphs. Namely, the problem is NP-complete for any fixed k >= 5 and it is polynomial-time for any k <= 3. This leaves open the case k = 4 for connected graphs.

  • The complexity of zero-visibility cops and robber
    • Dariusz Dereniowski
    • Danny Dyer
    • Ryan M. Tifenbach
    • Boting Yang
    2015 Pełny tekst THEORETICAL COMPUTER SCIENCE

    We consider the zero-visibility cops & robber game restricted to trees. We produce a characterisation of trees of copnumber k and We consider the computational complexity of the zero-visibility Cops and Robber game. We present a heavily modified version of an already-existing algorithm that computes the zero-visibility copnumber of a tree in linear time and we show that the corresponding decision problem is NP-complete on a nontrivial class of graphs.

  • The compositional space of exhaled breath condensate and its link to the human breath volatilome
    • Franco Moritz
    • Monika Janicka
    • Agata Zygler
    • Sara Forcisi
    • Agata Kot-Wasik
    • Jacek Kot
    • István Gebefüg
    • Jacek Namieśnik
    • Philippe Schmitt-Kopplin
    2015 Journal of Breath Research

    Breath analysis is commonly understood to target gaseous or volatile organic compounds (VOCs) for the characterization of different pathologies. Targeted analysis is most effective if a working hypothesis can be based on a plethora of data. The recently published volatilome builds an optimal basis for organizing powerful target sets. However, the origin and pathways of biosynthesis of many VOCs are not known, which complicates the formulation of useful hypotheses. To find the missing link between VOCs and their origin, it is necessary to analyze their precursor fluids themselves. In order to provide condensation nuclei for the generation of future hypotheses, we provide the compositional space over 23 samples of the unperturbed human exhaled breath condensate (EBC) metabolome. We propose a way to connect the compositional spaces of both VOCs and EBC so as to gain insight into the most probable form of VOC precursors. In a way analogous to tandem MS it is possible to create a mass difference network over compositional data by linking compositions with mass differences that are designed to mimic biochemical reactions. We propose to use mass difference enrichment analysis (MDEA) in order to mine probable relations between VOCs and their precursor fluids. We have found 2691 EBC compositions and linked them to 235 breath VOC compositions that correspond to 848 individual compounds. We found that VOCs are likely to be found as hexose conjugates or as amino acid conjugates with Glutamine or Asparagine playing a major role. Furthermore, we found that dicarboxylic acid mass differences may be more indicative for oxidative stress than oxygenation-hydrogenation sequences.

  • The computational complexity of the backbone coloring problem for bounded-degree graphs with connected backbones
    • Robert Janczewski
    • Krzysztof Turowski
    2015 INFORMATION PROCESSING LETTERS

    Given a graph G, a spanning subgraph H of G and an integer λ>=2, a λ-backbone coloring of G with backbone H is a vertex coloring of G using colors 1, 2, ..., in which the color difference between vertices adjacent in H is greater than or equal to lambda. The backbone coloring problem is to find such a coloring with maximum color that does not exceed a given limit k. In this paper, we study the backbone coloring problem for bounded-degree graphs with connected backbones and we give a complete computational complexity classification of this problem. We present a polynomial algorithm for optimal backbone coloring for subcubic graphs with arbitrary backbones. We also prove that the backbone coloring problem for graphs with arbitrary backbones and with fixed maximum degree (at least 4) is NP-complete. Furthermore, we show that for a special case of graphs with fixed maximum degree at least 5 and λ>=4 the problem remains NP-complete even for spanning tree backbones.

  • The computational complexity of the backbone coloring problem for planar graphs with connected backbones
    • Robert Janczewski
    • Krzysztof Turowski
    2015 Pełny tekst DISCRETE APPLIED MATHEMATICS

    In the paper we study the computational complexity of the backbone coloring problem for planar graphs with connected backbones. For every possible value of integer parameters λ≥2 and k≥1 we show that the following problem: Instance: A simple planar graph GG, its connected spanning subgraph (backbone) HH. Question: Is there a λ-backbone coloring c of G with backbone H such that maxc(V(G))≤k? is either NP-complete or polynomially solvable (by algorithms that run in constant, linear or quadratic time). As a result of these considerations we obtain a complete classification of the computational complexity with respect to the values of λ and k. We also study the problem of computing the backbone chromatic number for two special classes of planar graphs: cacti and thorny graphs. We construct an algorithm that runs in O(n^3) time and solves this problem for cacti and another polynomial algorithm that is 1-absolute approximate for thorny graphs.

  • The Conservation and Preservation of Gdynia`s Modernist Architecture
    • Robert Hirsch
    2015

    The paper presents the introducing of legal protection in Gdynia City Center and conservation of modern monuments built before WWII in this town

  • The Dynamic Model of Magnetic Hysteresis
    • Andrzej Wilk
    • Michał Michna
    2015

    This paper presents the scalar dynamic magnetic hysteresis model based on the Preisach theory. The important role in this theory played hysteresis operator states. The changes of these operators` states are not immediate in the dynamic model but they are a function of time and parameter k representing the magnetic properties of the material. In this paper the transient state of the hysteresis operator is defined by the nonlinear first order differential equation. The implementation of the dynamic hysteresis is additionally associated with feedback hysteresis model. This allows for obtaining a more accurate model for low and high magnetization frequencies. The material parameter k was determined for the toroidal tape wound core made of anisotropic sheet steel ET114-27. This paper presents the magnetic hysteresis loop simulation results for the different magnetization frequencies.

  • The effect of anionic surfactant concentration on activated sludge condition and phosphate release in biological treatment plant
    • Alina Dereszewska
    • Stanisław Cytawa
    • Renata Tomczak-Wandzel
    • Krystyna Mędrzycka
    2015 Pełny tekst POLISH JOURNAL OF ENVIRONMENTAL STUDIES

    This paper discusses the influence of a wide range of anionic surfactant concentrations on activated sludge. Linear alkylbenzene sulphonate (LAS) was chosen as an example of a commonly used anionic surfactant. The fate of the surfactant during biological treatment of wastewater was tested. The effect of surfactant on glucose and starch removal was studied.

  • The effect of circular saw blade clamping diameter on its resonant frequencies
    • Anna Danuta Kaczmarek-Penia•kova
    • Kazimierz Orłowski
    • Lubomir Javorek
    2015

    In this paper results of comparison of characteristic resonant frequencies of circular saw blades as a function of saw clamping diameter from the impact test are presented. Obtained results revealed that proportionally with the increase of the saw clamping diameter also the dynamical stiffness of the saw blade increased. As a consequence of that the resonant frequencies of the saw blade move to higher values. Moreover, with the increase of the saw blade clamping diameter for higher frequencies of forcing vibration of the saw blade the amplitude of vibration are expected to be decreased.

  • The Effect of Cryogenic Treatment on Microstructure and Mechanical Response of AISI D3 Tool Steel Punches
    • Y. Arslan
    • I. Uygur
    • Agata Jażdżewska
    2015 JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME

    Recently, deep cryogenic treatment is performed to improve the mechanical responses (wear, hardness, fatigue, and thermal conductivity) of various steel components. Researchers have tried to evaluate the eco-friendly and nontoxic process to optimize the parameters. Cold-shearing punches used to manufacture various holes that undergo severe impact loading and wear in the metal forming process. This study concerns the effect of soaking time (24 hr, 36 hr) at liquid nitrogen temperature (−145 °C) during the deep cryogenic treatment on the microstructural changes which are carbide distribution and retained austenite percentage of AISI D3 tool steel punches. It was shown that the deep cryogenic treatment reduces retained austenite and enhanced uniform distribution of carbide particles. It is concluded that for significantly improved punch life and performance, it is an advisable application of 36 hr deep cryogenic treatment.

  • The effect of current signal filtering method on the value of cutting power while sawing wood
    • Kazimierz Orłowski
    • Jakub Sandak
    • Tomasz Ochrymiuk
    • Marcin Lackowski
    • Anna Sandak
    2015 Pełny tekst Annals of WULS, Forestry and Wood Technology

    The goal of this work was to investigate an effect of various signal pre-processings on the outline of the electrical power curve and its influence on the measured cutting force estimation. Two signal processing methods were selected for the needs of the experiment, including digital filter and wavelet transform. The filter used was Butterworth, 3rd order band-stop with the cut-out band from 45 Hz to 55 Hz. The second approach performed was the wavelet decomposition. The carried out results analyses revealed that the properly selected digital processing method of the measured current signal affected by the electrical noise of the constant frequency of 50 Hz does not decrease of information which is carried along by the root signal. The best results were obtained if the root signal has been processed with Discrete Wavelet Transform.

  • The effect of nanoparticles size on photocatalytic and antimicrobial properties of Ag-Pt/TiO2 photocatalysts
    • Anna Zielińska-Jurek
    • Zhishun Wei
    • Izabela Wysocka
    • Piotr Szweda
    • E. Kowalska
    2015 APPLIED SURFACE SCIENCE

    Ag-Pt-modified TiO2 nanocomposites were synthesized using the sol–gel method. Bimetallic modified TiO2 nanoparticles exhibited improved photocatalytic activity under visible-light irradiation, better than monometallic Ag/TiO2 and Pt/TiO2 nanoparticles (NPs). All modified powders showed localized surface plasmon resonance (LSPR) in visible region. The photocatalysts’ characteristics by X-ray diffractometry (XRD), scanning transmission electron microscopy (STEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption (BET method for specific surface area) showed that sample with the highest photocatalytic activity had anatase structure, about 93 m2/g specific surface area, maximum plasmon absorption at ca. 420 nm and contained small NPs of silver of 6 nm and very fine platinum NPs of 3 nm. The photocatalytic activity was estimated by measuring the decomposition rate of phenol in 0.2 mM aqueous solution under Vis and UV/vis light irradiation. It was found that size of platinum was decisive for the photocatalytic activity under visible light irradiation, i.e., the smaller Pt NPs were, the higher was photocatalytic activity. While, antimicrobial activities, estimated for bacteria Escherichia coli and Staphylococcus aureus, and pathogenic fungi belonging to Candida family, were only observed for photocatalysts containing silver, i.e., Ag/TiO2 and Ag-Pt/TiO2 nanocomposites.

  • The effect of pre-hydrogen charging on corrosion behaviour of superduplex stainless steel welded joints
    • Jerzy Łabanowski
    • Aleksandra Świerczyńska
    • Joanna Michalska
    2015 Solid State Phenomena

    The paper presents results of research undertaken to determine the influence of hydrogen on passivity and corrosion resistance of 2507 super duplex stainless steel welded joints. Butt welded joints were made with low heat input using flux corded arc welding (FCAW) method. Coupons of 5.0 x 5.0 mm were cut from the welded joints containing weld metal (WM), heat affected zone (HAZ) and parent metal (PM). Hydrogen was introduced into the samples by cathodic current method under galvanostatic condition at room temperature. Corrosion resistance was qualified with the polarization curves registered in synthetic sea water. Electrochemical hydrogen charging affected the native passive layer. The internal hydrogen shifted corrosion potential to the more active direction and cause an increase in corrosion current density. The corrosion sensitivity increases for higher current density applied during hydrogen charging. Weld metal area has been revealed as the most sensitive to corrosion attack.

  • THE EFFECT OF THE FRICTION OF THE REFUSE INSIDE THE REFUSE COLLECTION VEHICLE BODY ON THE WORKING PARAMETERS OF THE COMPACTION MECHANISM
    • Jacek Czyżewicz
    • Michał Wasilczuk
    2015 Pełny tekst TRIBOLOGIA

    Mechanizm prasujący pojazdu do usuwania odpadów z pojemników (w skrócie PUOP) spełnia dwie funkcje. W pierwszym etapie zagęszcza zebrane z pojemników odpady, a następnie przemieszcza je w głąb skrzyni zbiorczej. Znajo-mość właściwości mechanicznych odpadów znajdujących się wewnątrz skrzyni może w znaczący sposób wpłynąć na poprawę wydajności pojazdu. Celem ba-dań było zwiększenie wydajności PUOP poprzez opracowanie  w oparciu o wyznaczony doświadczalnie współczynnik oporu odpadów  udoskonalonego algorytmu sterowania pracą mechanizmu prasującego. Rejestracja chwilowego położenia mechanizmów PUOP oraz ciśnienia w układzie hydraulicznym umoż-liwiła wyznaczenie wartości charakterystycznego dla danego typu odpadów współczynnika oporu o wnętrze skrzyni zbiorczej. W kolejnym etapie prac ba-dawczych wartość wyznaczonego współczynnika oporu wykorzystana została do opracowania nowego algorytmu sterującego pracą mechanizmu prasującego PUOP. W artykule zamieszczone zostały wybrane charakterystyki współczynnika oporu odpadów o wnętrze skrzyni zbiorczej obrazujące znaczące różnice otrzymanych wartości w zależności od analizowanej frakcji odpadów. Opisano również metodę ich wyznaczania oraz ograniczenia tej metody.