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Repozytorium publikacji
Politechniki Gdańskiej

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  • Diagnostyka analogowych filtrów wielosekcyjnych oparta na klasyfikato-rach neuronowych z dwucentrowymi funkcjami bazowymi
    • Michał Kowalewski
    • Zbigniew Czaja
    2014 Pełny tekst Measurement Automation Monitoring

    Przedmiotem artykułu jest zastosowanie klasyfikatora z dwucentrowymi funkcjami bazowymi do lokalizacji uszkodzeń w wielosekcyjnych torach analogowych elektronicznych systemów wbudowanych sterowanych mikrokontrolerem. Przedstawiono szczegóły procedury pomiarowej oraz metody detekcji i lokalizacji uszkodzeń toru analogowego z wykorzysta-niem klasyfikatora DB zaimplementowanego w postaci algorytmicznej w kodzie programu mikrokontrolera. Omówiono konstrukcję klasyfikatora DB oraz metodę wyznaczania jego parametrów na przykładzie wielosek-cyjnego toru analogowego złożonego z trzech filtrów dolnoprzepustowych 2-go rzędu o strukturze Sallena-Keya.

  • Diagnostyka analogowych filtrów wielosekcyjnych oparta na magistrali testującej IEEE1149.1
    • Zbigniew Czaja
    • Bogdan Bartosiński
    2014 Pełny tekst Measurement Automation Monitoring

    Przedstawiono nową koncepcję testera JTAG BIST do samo-testowania torów analogowych opartych na wielosekcyjnych filtrach wyższego rzędu w mieszanych sygnałowo mikrosystemach elektronicznych sterowanych mikrokontrolerami i wyposażonych w magistralę testującą IEEE1149.1 (JTAG). Bazuje ona na metodzie diagnostycznej opartej na przekształce-niu transformującym próbki odpowiedzi czasowych kolejnych sekcji filtra pobudzonego impulsem prostokątnym na krzywe identyfikacyjne w prze-strzeni pomiarowej. Metoda ta pozwala na detekcję i lokalizację pojedyn-czych uszkodzeń parametrycznych w pierwszej w kolejności uszkodzonej sekcji filtra.

  • Diagnostyka stanu technicznego rurociągów stalowych z wykorzystaniem tłoków ultradźwiękowych wysokiej rozdzielczości
    • Paweł Raczyński
    • Krzysztof Warnke
    2014

    W pracy przedstawiono wybrane przykłady możliwości pomiarowych ultradźwiękowych tłoków wysokiej rozdzielczości do badania stanu ścianek rurociągów. Przedstawiono techniki zmierzające do precyzyjnej lokalizacji wykrywanych wad oraz opisano znaczenie i metodykę oszacowania trendów rozwojowych wad. Wskazano również na możliwości synergii informacji otrzymywanych różnymi technikami pomiarowymi w oparciu o systemy GIS. Na koniec podano przykłady zdolności detekcyjnej tłoków w stosunku do wad materiałowych i deformacji geometrycznych.

  • Diagnostyka stanu technicznego rurociągów stalowych z wykorzystaniem tłoków ultradźwiękowych wysokiej rozdzielczości
    • Paweł Raczyński
    • Krzysztof Warnke
    2014 Ochrona przed Korozją

    W pracy przedstawiono wybrane przykłady mozliwosci pomiarowych ultradźwiękowych tłoków wysokiej rozdzielczości do badania stanu ścianek rurociągów. Przedstawiono techniki zmierzające do precyzyjnej lokalizacji wykrywanych wad oraz opisano znaczenie i metodykę oszacowania trendów rozwojowych wad. Wskazano również na możliwości synergii informacji otrzymywanych różnymi technikami pomiarowymi w oparciu o systemy GIS. Na koniec podano przykłady zdolności detekcyjnej tłoków w stosunku do wad materiałowych i deformacji geometrycznych.

  • Diagnostyka ultradźwiękowa mostowej belki prefabrykowanej typu T metodą młoteczkową
    • Aleksandra Kuryłowicz-Cudowska
    • Magdalena Rucka
    • Krzysztof Wilde
    2014 Przegląd Budowlany

    Zastosowanie prefabrykacji w budowie obiektów mostowych pozwala optymalizować zużycie energii i materiałów i tym samym redukować koszty budowanego obiektu. Prefabrykowane belki sprężone mogą występować jako elementy kablobetonowe wykonywane bezpośrednio na placu budowy lub powstawać w zakładzie prefabrykacji jako elementy strunobetonowe. Elementy prefabrykowane wytwarzane w warunkach przemysłowych muszą spełniać wymagania wysokiej trwałości, zapewniać należyte właściwości użytkowe oraz estetyczne. Uszkodzenia w prefabrykowanych belkach mostowych mogą powstawać na etapie produkcji, w trakcie transportu lub ich montażu i mogą mieć charakter trudno dostrzegalnych rys o małych rozwartościach. Niniejszy artykuł poświęcony jest detekcji stref zarysowań mostowej belki strunobetonowej typu T metodą młoteczkową. Badania diagnostyczne, bazujące na zjawisku propagacji fal ultradźwiękowych, są szczególnie istotne przy diagnostyce elementów konstrukcyjnych już zamontowanych w obiekcie budowlanym ze względu na ich nieinwazyjny charakter.

  • Dielectric Properties of BiNbO<sub>4</sub>-Based Ceramic-Polymer Composites with 0-3 Connectivity
    • Agata Lisińska-Czekaj
    • Joanna Micior
    • Małgorzata Adamczyk
    • Dionizy Czekaj
    2014 Key Engineering Materials

    In the present study two-phase BiNbO4//PVDF composites with 0-3 connectivity were studied by impedance spectroscopy within the frequency range Δν=100Hz-1MHz at room temperature. Polyvinylidene fluoride (PVDF) acted as a matrix whereas bismuth niobate (BiNbO4) powder acted as a dispersed phase. The volume fraction of the ceramic phase was cV=2, 4, 6, 8, 10, 16 and 20vol%. Analysis of the impedance data registered for composites as well as for BiNbO4 ceramics and PVDF polymer was performed on the base of complex dielectric permittivity mathematical formalism. It was found by impedance spectroscopy that concentration of the dispersed phase had an effect on dielectric properties of ceramic-polymer composite. Experimental data of impedance spectroscopy were fitted to the corresponding equivalent circuit using the complex non-linear least squares method. An equivalent electric circuit consisting of a series combination of two parallel combinations of a resistance R and a constant phase element CPE was found to describe well the dynamic dielectric response of the objects under study. Parameters of the equivalent electric circuit were calculated and it was found that two distinct relaxation processes were present in the composite samples. It was also found that volume fraction of the dispersed phase cV=8vol% corresponded to a local minimum of resistance whereas cV=10vol% of the dispersed phase corresponded to a local minimum of capacitance.

  • Dielectric properties of modified graphene oxide filled polyurethane nanocomposites and its correlation with rheology
    • Kishor Sadasivuni
    • Deepalekshmi Ponnamma
    • Bijandra Kumar
    • Michał Strankowski
    • Ruth Cardinaels
    • Paula Moldenaers
    • Thomas Sabu
    • Yves Grohens
    2014 COMPOSITES SCIENCE AND TECHNOLOGY

    This study aims at investigating the dynamic mechanical, dielectric and rheological properties of reinforced polyurethane (PU) nanocomposites containing hydrophilic graphene oxide (GO) and/or hydrophobic modified graphene oxide (mGO) sheets. The organic modification of GO was performed with 4,4′-methylenebis (phenyl isocyanate) (MDI) and the samples were prepared by solvent mixing. We found that addition of mGO provides a more significant increase in the dielectric permittivity as compared to the addition of GO. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) spectroscopy demonstrate the more effective dispersion of thin exfoliated sheets of mGO in the PU matrix as compared to unmodified GO. This qualitative morphology observation is correlated with the quantitative results inferred from the dynamic mechanical analysis, rheology and dielectric studies. The viscoelastic Payne effect is noticed for all nanocomposites and the filler–filler and polymer–filler interactions are studied by applying the Kraus and Maier and Goritz models. The non-linear viscoelastic behavior of the PU nanocomposites is in good agreement with the Maier and Goritz model, which includes the effects of the adsorption/desorption of PU chains on the filler surface. The observed results underline the possibilities of PU composites with organically modified GO sheets in capacitor applications.

  • Difference functional inequalities and applications.
    • Anna Szafrańska
    2014 Pełny tekst Opuscula Mathematica

    The paper deals with the difference inequalities generated by initial boundary value problems for hyperbolic nonlinear differential functional systems. We apply this result to investigate the stability of constructed difference schemes. The proof of the convergence of the difference method is based on the comparison technique, and the result for difference functional inequalities is used. Numerical examples are presented.

  • Diffusible hydrogen content in deposited metal of multilayer welded joints
    • Dariusz Fydrych
    • Aleksandra Świerczyńska
    • Grzegorz Rogalski
    2014 Metallurgy and Foundry Engineering

    The article describes manufacturing technology of multilayer joints in terms of control the diffusible hydrogen content. Diffusible hydrogen content in deposited metal for multilayer welded joints made of covered rutile electrodes or covered cellulosic and basic electrodes was determined. It was found that after four beads, the diffusible hydrogen content decreases in the case of the first technology from 36 ml/100 g to 18 ml/100 g while in the second of about 40 ml/100 g to a level of 12 ml/100 g. The explanation of the mechanisms responsible for this phenomenon and directions for further study were proposed.

  • Diffusible Hydrogen Control in Flux Cored Arc Welding Process
    • Dariusz Fydrych
    • Aleksandra Świerczyńska
    • Jacek Tomków
    2014 Key Engineering Materials

    One of the types of hydrogen degradation of steel welded joints is cold cracking. The direct cause of the formation of cold cracks is simultaneous presence of hydrogen, residual stresses and brittle structure. The way of preventing the occurring of degradation is to eliminate at least one of these factors. Practice has shown that the best solution is to control the amount of hydrogen in deposited metal. In this paper an experimental evaluation of the effect of the welding parameters on the content of diffusible hydrogen in deposited metal obtained from rutile flux cored wire grade H10 was carried out. The state of the art of considered issues was described and results of preliminary investigations were presented. Five factors were considered: the flow rate of shielding gas, the welding current, the arc voltage, the welding speed and the electrode extension. All factors were optimized using a Plackett-Burman design to get the most relevant variables. The level of diffusible hydrogen was determined by a glycerin test. The results of the experiment indicate that appropriate choice of welding parameters may significantly reduce diffusible hydrogen content in deposited metal.

  • Digital Fingerprinting Based on Quaternion Encryption Scheme for Gray-Tone Images
    • Bartosz Czaplewski
    • Mariusz Dzwonkowski
    • Roman Rykaczewski
    2014 Pełny tekst Journal of Telecommunications and Information Technology

    In this paper a new idea of digital images fingerprinting is proposed. The method is based on quaternion encryption in the Cipher Block Chaining (CBC) mode. Quaternion sare hyper-complex numbers of rank 4 and thus often applied to mechanics in three-dimensional space. The encryption algorithm described in the paper is designed for gray-tone images but can easily be adopted for color ones. For the encryption purpose, the algorithm uses the rotation of data vectors presented as quaternions in a three-dimensional space around another quaternion (key). On the receiver's side, a small amount of unnoticeable by human eye errors occurs in the decrypted images. These errors are used as a user's digital fingerprint for the purpose of traitor tracing in case of copyright violation. A computer-based simulation was performed to scrutinize the potential presented quaternion encryption scheme for the implementation of digital fingerprinting. The obtained results are shown at the end of this paper.

  • Digital fingerprinting for color images based on the quaternion encryption scheme
    • Bartosz Czaplewski
    • Mariusz Dzwonkowski
    • Roman Rykaczewski
    2014 PATTERN RECOGNITION LETTERS

    In this paper we present a new quaternion-based encryption technique for color images. In the proposed encryption method, images are written as quaternions and are rotated in a three-dimensional space around another quaternion, which is an encryption key. The encryption process uses the cipher block chaining (CBC) mode. Further, this paper shows that our encryption algorithm enables digital fingerprinting as an additional feature. This feature follows from some artifacts which occur in the decrypted image. These artifacts can be maintained at such a low level that they remain imperceptible to the human eye and unique for each key. These artifacts are considered to be users’ fingerprints and can be used to identify pirates in the event of illegal redistribution of multimedia data. Identification of pirates is performed in the form of non-blind detection. The purpose of this paper is to report a new approach to digital fingerprinting and to point out the method’s existing flaws which need future research. A computer-based simulation was conducted to examine the potential of our quaternion encryption scheme for the implementation of digital fingerprinting.

  • Digital signal processing applied to the modernization of Polish Navy sonars
    • Jacek Marszal
    2014 Pełny tekst Polish Maritime Research

    The article presents the equipment and digital signal processing methods used for modernizing the Polish Navy’s sonars. With the rapid advancement of electronic technologies and digital signal processing methods, electronic systems, including sonars, become obsolete very quickly. In the late 1990s a team of researchers of the Department of Marine Electronics Systems, Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, began work on modernizing existing sonar systems for the Polish Navy. As part of the effort, a methodology of sonar modernization was implemented involving a complete replacement of existing electronic components with newly designed ones by using bespoke systems and methods of digital signal processing. Large and expensive systems of ultrasound transducers and their dipping and stabilisation systems underwent necessary repairs but were otherwise left unchanged. As a result, between 2001 and 2014 the Gdansk University of Technology helped to modernize 30 sonars of different types.

  • Dilemmas associated with the implementation of quality management systems in Polish smaller health care units
    • Piotr Grudowski
    2014

    The article presents the considerations and recommendations for the implementation of the process-oriented quality management systems (QMS) in small health care units. As an example, the unit providing services for children with disabilities (therapy and rehabilitation) localized in northern part of Poland have been selected. The essential elements of the implementation of the quality system, taking into account the objectives process orientation have been described. Particular attention was given to the methods of monitoring therapeutic processes. The key benefits of the implementation of the QMS and the possible use of CAF model in the improvement of the organization are also presented.

  • Dimensional Synthesis of Coupled-Resonator Pseudoelliptic Microwave Bandpass Filters with Constant and Dispersive Couplings
    • Łukasz Szydłowski
    • Natalia Leszczynska
    • Michał Mrozowski
    2014 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES

    In this paper, we propose a novel technique for the dimensional synthesis of coupled-resonator pseudoelliptic microwave filters with constant and dispersive couplings. The proposed technique is based on numerical simulations of small structures, involving up to two adjacent resonators, and it accounts for a loading effect from other resonators by replacing them with terminations coupled through appropriately scaled inverters. The dimensions of the resonators and coupling elements are determined by an optimization process that matches the zeros and poles of the simulated response of a low-order circuit consisting of one or two coupled resonators connected to a source and to matched loads with the eigenvalues of a submatrix obtained from the coupling matrix of the lumped-element model of the filter. To assure high accuracy and rapid convergence, a zero-pole optimization algorithm was used. The application of this method is illustrated with four examples involving a simple fourth-order open-loop microstrip filter with two transmission zeros, through a triplet with one transmission zero, a quadruplet with two asymmetric transmission zeros located on both sides of the passband, to a fourth-order waveguide filter with three transmission zeros. The validity of the method is confirmed by an experiment involving a filter with dispersive coupling realized in substrate-integrated waveguide (SIW) technology.

  • Direct amination of boron-doped diamond by plasma polymerized allylamine film
    • Robert Bogdanowicz
    • M. Sawczak
    • P. Niedziałkowski
    • Patrycja Zięba
    • B. Finke
    • Jacek Ryl
    • Tadeusz Ossowski
    2014 PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE

    A novel microwave pulsed-plasma based method for the modification of the hydrogen-terminated polycrystalline boron-doped diamond (BDD) with a thin film of polymerized allylamine (PPAAm) is reported. A modified BDD surface is resistant to hydrolysis and delamination and is characterized by a high density of positively charged amino groups. Pulsed microwave plasma was applied to improve the degree of cross-linking and bonding of the plasma polymeric films to BDD. The primary amino groups of the amine-modified Si/BDD surface were coupled with antraquinone derivatives as model electroactive compounds. Synthesized thin BDD-PPAAm films were investigated with X-ray photoelectron spectroscopy (XPS), laser induced fluorescence (LIF) and Fourier transform infrared spectroscopy (FT-IR). The FT-IR studies confirm that the molecular structure of the deposited layer reproduces the monomer structure with a partial transformation of amino groups into amide and nitrile. XPS results show that PPAAm film on an Si/BDD electrode is electrochemically stable within the range of polarization potentials between −1.1 and +1.1 V. The fluorescence properties of the PPAAm modified BDD surface makes its promising for application in sensors with optical readout. At the same time, the PPAAm film's durability investigated over a wide potential range makes it ideal for electrochemical sensors

  • Direct-Ultrasonic Assisted Microextraction Coupled with RTL-GC-FID/GC-MS as a Future Standard Procedure for Monitoring 26 potentially Allergenic Fragrances in Water Samples
    • Aleksandra Szreniawa-Sztajnert
    • Bożena Zabiegała
    2014

    This research topic grew up as a result of awareness of constant anthropogenic and natural input to the environment constituents of personal care products (PCPs) residues. This group of emerging pollutants encompasses a wide range of chemicals, including potentially allergenic fragrance compounds. The aim of the present study was to investigate presence of 26 fragrance allergens in water samples. Simple and rapid methodology based on direct-ultrasonic assisted liquid-liquid microextraction (USALLME) followed by gas chromatography with flame ionization detector (GC-FID) and gas chromatography with mass spectrometry (GC-MS) using Retention Time Locking has been developed. GC-MS analyses were performed with inlet pressure adjusted at 7.29 psi to lock a retention time at 27.500 min for n-pentadecane. GC-FID analyses were performed with inlet pressure adjusted to give a retention time of 70.000 min for n-pentadecane which was set up at 38.032 psi. Finally several real water samples were investigated with the application of the proposed method.

  • Discouraging Traffic Remapping Attacks in Local Ad Hoc Networks
    • Jerzy Konorski
    • Szymon Szott
    2014 Pełny tekst IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS

    Quality of Service (QoS) is usually provided in ad hoc networks using a class-based approach which, without dedicated security measures in place, paves the way to various abuses by selfish stations. Such actions include traffic remapping attacks (TRAs), which consist in claiming a higher traffic priority, i.e., false designation of the intrinsic traffic class so that it can be mapped onto a higher-priority class. In practice, TRAs can be executed in IEEE 802.11 ad hoc networks using the Enhanced Distributed Channel Access (EDCA) function. This attack is easy to perform yet hard to prevent. We propose a distributed discouragement scheme based on the threat of TRA detection and punishment. The scheme does not rely on station identities or a trusted third party, nor does it require tampering with the MAC protocol. We analyze an arising non-cooperative TRA game and find that under certain realistic assumptions it only incentivizes TRAs if they are harmless to other stations; otherwise the selfish stations are induced to learn that TRAs are counterproductive.

  • Discrete modeling of micro-structure evolution during concrete fracture using DEM
    • Michał Nitka
    • Andrzej Tejchman-Konarzewski
    2014 INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS

    W artykule pokazano wyniki dyskretne DEM dla betonu poddanego ściskaniu i rozciąganiu jednoosiowemu. Wyniki siła-przemieszczenie i zarysowania porównano z doświadczeniami. Szczególną uwagę zwrócono na zjawiska mikrostrukturalne podczas zarysowania na poziomie kruszywa.

  • Discrete simulations of a triaxial compression test for sand by DEM.
    • Jan Kozicki
    • Andrzej Tejchman-Konarzewski
    • Hans-Bernd Mühlhaus
    2014 Pełny tekst INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS

    Artykuł przedstawia wyniki symulacji dyskretnych dla ściskania trójosiowego stosując metodę elementów dyskretnych DEM. Symulacje wykonano dla piasku. Zastosowano kuli z momentami kontaktu do symulacji kształtu ziaren. Przeprowadzono analizy dla różnych zmiennych parametrów: średnica piasku, krzywa uziarnienia, kształt ziaren, wymiary próbki i warunki brzegowe.