2014 - Repozytorium publikacji - Politechnika Gdańska

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Publikacje z roku 2014

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Selected biotrends in development of epoxy resins and their composites
- Janusz Datta
- Marcin Włoch
2014 POLYMER BULLETIN
Epoxy resins and their fibre or particulate composites are widely used in various industries, including building, naval, aircraft, automotive and aerospace. Modern polymer science and technology focus on the development of green polymers and composites. There are two major areas of interest in the case of epoxy resins: the development of bio-based resins and the production of composites with natural fibers. One of the most interesting challenges is developing fully bio-based composites, that is epoxy resins based on renewable resources and natural fibers. This paper presents a review of literature on epoxy resins and hardeners based on renewable resources (especially vegetable oils) and epoxy composites with natural fibres. We also describe some of the effective methods of improving the mechanical properties of epoxy-natural fibres composites, including chemical modification of the fibre surface and the application of hybrid reinforcements.
Selected Technical Requirements for Photovoltaic Plant Interconnection with a Medium Voltage Grid
- Ryszard Zajczyk
- Bartosz Tarakan
- Krzysztof Tarakan
2014 Pełny tekst Acta Energetica
The article discusses some selected technical requirements, which according to these authors should be recognised and met by photovoltaic power plants connected to national distribution grids in the context of their likely development. This development today is limited, since Polish legislation has not implemented the relevant EU Directive [8]. The study points out the purposefulness of incorporating the necessary requirements in the applicable laws and regulations.
Selection Of Optimal Working Fluid For Use With Hybrid Microchannel-Microjet Heat Exchanger
- Rafał Andrzejczyk
- Tomasz Muszyński
2014
The paper presents the investigation to find best suited working fluid for a microjet- microchannel cooling module. In which microjets are impinging into the microchannels and forming a liquid film on the impingement surface. This technology takes benefits from two very attractive heat removal techniques. When laminar jets are impinging on the surface have a very high kinetic energy at the stagnation point, also in microchannels boundary layer is very thin allowing to obtain very high heat fluxes.
Selection of Visual Descriptors for the Purpose of Multi-camera Object Re-identification
- Piotr Dalka
- Damian Ellwart
- Grzegorz Szwoch
- Karol Lisowski
- Piotr Szczuko
- Andrzej Czyżewski
2014
A comparative analysis of various visual descriptors is presented in this chapter. The descriptors utilize many aspects of image data: colour, texture, gradient, and statistical moments. The descriptor list is supplemented with local features calculated in close vicinity of key points found automatically in the image. The goal of the analysis is to find descriptors that are best suited for particular task, i.e. re-identification of objects in a multi-camera environment. The analysis is performed using two datasets containing images of humans and vehicles recorded with different cameras. For the purpose of descriptor evaluation, scatter and clustering measures are supplemented with a new measure that is derived from calculating direct dissimilarities between pairs of images. In order to draw conclusions from multi-dataset analysis, four aggregation measures are introduced. They are meant to find descriptors that provide the best identification effectiveness, based on the relative ranking, and simultaneously are characterized with large stability (invariance to the selection of objects in the dataset). Proposed descriptors are evaluated practically with object re-identification experiments involving four classifiers to detect the same object after its transition between cameras’ fields of view. The achieved results are discussed in detail and illustrated with figures.
Selection Pressure in the Evolutionary Path Planning Problem
- Łukasz Kuczkowski
- Roman Śmierzchalski
2014 Advances in Intelligent Systems and Computing
This article compares an impact of using various post-selection methods on the selection pressure and the quality of the solution for the problem of planning the path for a moving object using the evolutionary method. The concept of selection pressure and different methods of post-selection are presented. Article analyses behaviour of post-selection for four options of evolutionary algorithms. Based on the results achieved, waveform diagrams were presented showing best and average fitness score depending on the generation. Those allowed to determine the selection pressure for each of the variants. The results presented allow to choose a post-selection method that maintains the population’s variety and the compromise between the exploration and exploitation phases. In study case problem of avoiding collisions at sea is analysed. The modelled environment includes static constraints (lands, canals, etc.) and dynamic objects (moving ships).
Self-Association of Amphotericin B: Spontaneous Formation of Molecular Structures Responsible for the Toxic Side Effects of the Antibiotic
- Joanna Starzyk
- Marcin Gruszecki
- Krzysztof Tutaj
- Rafal Luchowski
- Radosław Szlazak
- Piotr Waśko
- Wojciech Grudziński
- Jacek Czub
- Wiesław I. Gruszecki
2014 JOURNAL OF PHYSICAL CHEMISTRY B
Amphotericin B (AmB) is a lifesaving antibiotic used to treat deep-seated mycotic infections. Both the pharmaceutical activity and highly toxic side effects of the drug rely on its interaction with biomembranes, which is governed by the molecular organization of AmB. In the present work we present detailed analysis of self-assembly of AmB molecules in different environments, interesting from the physiological standpoint, based on molecular spectroscopy techniques: electronic absorption, circular dichroism, steady state and time-resolved fluorescence and molecular dynamic calculations. The results show that in the water medium, AmB self-associates to dimeric structures, referred to as "parallel" and "antiparallel". AmB dimers can further assembly into tetramers which can play a role of transmembrane ion channels, affecting electrophysiological homeostasis of a living cell. Understanding structural determinants of self-assembly of AmB opens a way to engineering preparations of the drug which retain pharmaceutical effectiveness under reduced toxicity.
Self-healing mechanism of metallopolymers investigated by QM/MM simulations and Raman spectroscopy
- Stephan Kupfer
- Linda Zedler
- Julien Guthmuller
- Stefan Bode
- Martin Hager
- Ulrich Schubert
- Jürgen Popp
- Stefanie Gräfe
- Benjamin Dietzek
2014 Pełny tekst PHYSICAL CHEMISTRY CHEMICAL PHYSICS
The thermally induced self-healing mechanisms in metallopolymers based on bisterpyridine complexes of iron(II) sulfate and cadmium(II) bromide, respectively, were studied by means of combined quantum mechanical/molecular mechanical (QM/MM) simulations and Raman spectroscopy. Two possible healing schemes, one based on a decomplexation of the cross-linking complexes and a second one relying on the dissociation of ionic clusters, have been addressed. Temperature-dependent Raman spectroscopy displayed bathochromic shifts of the Raman intensity pattern upon heating. QM/MM simulations on the polymer models assign these alterations to a partial decomplexation of the metal terpyridine complexes, i.e. signals originating from free terpyridine ligands increase upon heating. Thus, a healing mechanisms based on partial decomplexation of the cross-linking complexes is suggested. The possibility that the dissociation of ionic clusters, which are assumed to be present in this class of self-healing polymers, is also responsible for the self-healing process was investigated as well. However, such calculations on model clusters revealed relatively strong binding of the clusters, which renders reversible cluster breaking and reformation upon temperature cycling in the range up to 100 1C unlikely.
Self-refraction of acoustic pulses with shock fronts in some nonequilibrium media
- Anna Perelomova
2014 Pełny tekst CANADIAN JOURNAL OF PHYSICS
The nonlinear self-refraction of acoustic pulsed beams, which include shock fronts, is studied. The medium of sound propagation is a gas where thermodynamically nonequilibrium processes take place, such as exothermic chemical reaction or excitation of vibrational degrees of a molecule’s freedom. Comparative analysis of the features of sound propagation over gases where pure nonlinear attenuation of the shock wave occurs, and gases with nonequilibrium and equilibrium processes, is
Self-tuning adaptive frequency tracker
- Michał Meller
2014 DIGITAL SIGNAL PROCESSING
An automatic gain tuning algorithm is proposed for a recently introduced adaptive notch filter. Theoretical analysis and simulations show that, under Gaussian random-walk type assumptions, the proposed extension is capable of adjusting adaptation gains of the filter so as to minimize the mean-squared frequency tracking error without prior knowledge of the true frequency trajectory. A simplified one degree of freedom version of the filter, recommended for practical applications, is proposed as well.
Semantic Driven Table Understanding in Born-Digital Documents
- Jacek Siciarek
2014
This paper presents a new approach to table understanding, suitable for born-digital PDF documents. Advance beyond the current state of the art in table understanding is provided by the proposed reverse MVC method, which takes advantage of only partial logic structure loss (degradation) in born-digital PDF documents, as opposed to unrecoverable loss (deterioration) taking place in scan based PDF documents.
Sensitivity analysis of a composite footbridge
- Tomasz Ferenc
2014
This work include an example of sensitivity analysis for the design of a composite footbridge. A sandwich structure is used, consisting two high-strength skins separated by a core material. The analysis was conducted for two numerical models. The first one is a simple, single-span beam of a composite cross-section (laminate and foam), with different Young’s modulus for each material. Calculations were made by means of a MATLAB-based Finite Element Method code. Next a 3D shell-solid model was considered, computed by the SOFISTIK. The sensitivity analysis investigated how the variation of thickness of individual elements of cross-section, acts on the middle-span deflection of a footbridge.
Sensitivity of entanglement decay of quantum-dot spin qubits to the external magnetic field
- Paweł Mazurek
- Katarzyna Roszak
- Ravindra W. Chhajlany
- Paweł Horodecki
2014 Pełny tekst PHYSICAL REVIEW A
We study the decay of entanglement of quantum-dot electron-spin qubits under hyperfine-interaction-mediated decoherence.We show that two-qubit entanglement of a single entangled initial state may exhibit decay characteristic of two disentanglement regimes in a single sample, when the externalmagnetic field is changed. The transition is manifested by the suppression of time-dependent entanglement oscillations which are superimposed on the slowly varying entanglement decay related to phase decoherencewhich results in oscillatory behavior of entanglement sudden death time as a function of the magnetic field. This unique behavior allows us to propose the doublequantum- dot two-electron spin Bell state as a promising candidate for precise measurements of themagnetic field.
SENSORY GARDENS INCLUSIVELY DESIGNED FOR VISUALLY IMPAIRED USERS.
- Monika Trojanowska
2014
This paper discusses the design of sensory gardens, created especially to provide for the needs of sight impaired children and youth. These gardens should be inclusively available to general public. A sensory garden may have both therapeutic and educational effects. The research findings concerning therapeutic effects of contact with nature on children and youth are reviewed. The design problems related to providing a space for education and development of sight impaired children are presented. The case study of sensory garden of spatial orientation, accessible to disabled and non-disabled in Owińska, near Poznan in Poland is provided. The post-occupancy evaluation results are discussed.
Separation of the effects of notch and macro residual stress on the MFL signal characteristics
- Zbigniew Usarek
- Bolesław Augustyniak
- Marek Augustyniak
2014 IEEE TRANSACTIONS ON MAGNETICS
Magnetic flux leakage (MFL) distribution for three configurations of samples has been investigated in order to study the influence of notch and plastic deformation separately as well as together. Samples have been made of S355 steel. The MFL signal measurements were carried out along the longest dimension of the sample over a length of 120 mm. Two components of magnetic field were measured: 1) tangential to the main axis and 2) normal to the largest surface of the sample. Study has shown that geometrical effect, related to the notch presence, as well as plastic deformation with associated compressive macroresidual stresses, together are responsible for the specific MFL distribution above the sample. In order to confirm the assumption that the decrease of the permeability in the central part of the sample and the change of cross section are the main sources of the MFL anomaly, disrupting flux from demagnetization field, a series of simulations has been made. Simulation results coincide with those obtained experimentally and thus confirming the above hypothesis.
Serwisy WWW jako instrument kształtowania relacji z klientem usług medycznych
- Beata Basińska
- Dariusz Dąbrowski
- Marcin Sikorski
2014 Pełny tekst Roczniki Kolegium Analiz Ekonomicznych
Wprowadzenie: W artykule podjęto problem oceny użyteczności serwisów WWW i badania postaw lojalnościowych e-klientów korzystających z serwisów WWW usług medycznych. Celem badania była wstępna walidacja metody do oceny jakości użytkowej serwisów WWW usług medycznych oraz określenie związków pomiędzy cechami jakości użytkowej serwisów WWW a cechami relacyjnymi, takimi jak: satysfakcja, chęć powrotu oraz zamiar rekomendowania serwisu WWW innym osobom. Metodologia: Badania eksperymentalne zostały przeprowadzone na próbce polskich użytkowników usług on-line (n=15) oraz obejmowały wybrane serwisy internetowe (n=2) prywatnych placówek zdrowotnych. Zastosowano kwestionariusz ankietowy do pomiaru czynników użytkowych i relacyjnych. Metoda oceny jakości użytkowej serwisów WWW zawierała dziewięć czynników: klarowność wizualna, łatwość obsługi, prowadzenie użytkownika, zawartość informacyjna, interaktywność z dostawcą usługi, personalizacja, demonstracja usługi, rekomendacje, dbałość o klienta. Do czynników relacyjnych zaliczono: satysfakcję z korzystania z serwisu, chęć powrotu do serwisu oraz zamiar rekomendowania serwisu znajomemu. Wyniki: Zaproponowana metoda różnicowała testowane serwisy WWW instytucji świadczących usługi medyczne, co zostało również potwierdzone za pomocą analizy podobieństwa profilowego Najwyżej oceniane były klarowność wizualna i łatwość obsługi. Najniższe oceny dotyczyły rekomendacji i demonstracji usługi. Większość czynników jakości użytkowej była wzajemnie skorelowana, z wyjątkiem czynnika rekomendacje. Wraz ze wzrostem oceny czynników jakości użytkowej rosła satysfakcja, chęć powrotu do serwisu i zamiar rekomendowania polecenia serwisu WWW innym osobom. Najsłabszy związek zaobserwowano pomiędzy czynnikiem rekomendacje a satysfakcją z użytkowania serwisu oraz chęcią powrotu do serwisu. Wnioski: Wstępna walidacja metody do oceny jakości użytkowej serwisów WWW usług medycznych została potwierdzona.
Sessile droplet contact angle of water–Al2O3, water–TiO2 and water–Cu nanofluids
- Janusz Cieśliński
- Katarzyna Ronewicz
2014 Pełny tekst EXPERIMENTAL THERMAL AND FLUID SCIENCE
This work presents measurements of the contact angle of sessile droplets for three nanofluids, i.e. water–Al2O3, water–TiO2 and water–Cu. The plates made of glass, anodized aluminium and stainless steel of different roughness served as substrates. Ultrasonic vibration was used for 30–60 min in order to stabilise the dispersion of the nanoparticles. Nanoparticles were tested at the concentration of 0.01%, 0.1%, and 1% by weight. Three methods of contact angle measurement were applied. The contact angle was established directly by use of a KRÜSS DSA10 goniometer or – building on digital images of droplets, an appropriate geometrical approach and tangent methods were applied. The study revealed that the droplet contact angle of nanofluids depends on surface roughness, type of substrate, material of nanoparticles, and concentration of nanoparticles.
Set of Experience Knowledge Structure (SOEKS) and Decisional DNA (DDNA): Past, Present and Future
- Edward Szczerbicki
- Cesar Sanin
2014 CYBERNETICS AND SYSTEMS
This article reviews research work on set of experience knowledge structure (SOEKS)-decisional DNA (DDNA) done in the past, ongoing, and planned for the future. Firstly, the concept of the knowledge representation technique of SOEKS-DDNA is discussed, and then an attempt is made to organize the past research related with it in chronological order. This work focuses on the review on SOEKS-DDNA, its application in different domains, the various implementation platforms, as well as its benefits and its limitations. The second part of this article provides an idea of the SOEKS-DDNA-related research endeavors currently carried out by us and the last part is a sneak peek into our planned future work.
SiC-based phase-shift dual half bridge DC-DC converter as a key component of multilevel cascaded MV converters
- Marek Adamowicz
- Patrick Strankowski
- Jędzej Pietryka
- Janusz Szewczyk
- Jarosław Guziński
2014 Pełny tekst Przegląd Elektrotechniczny
The paper describes SiC-based dual half bridge (DHB) DC-DC converter considered as a key component of high frequency isolated multilevel cascaded medium voltage converters. Two topologies of bi-directional DC-DC converters: the resonant half-bridge DC-DC converter and the phase-shift DHB converter are compared in the paper. Experimental results of SiC-based 50 kHz DHB DC-DC converter are presented in the paper.
Sieci, przyłącza i instalacje wodociągowe oraz kanalizacyjne. Wyraźna granica
- Mariusz Jarmulewski
2014 Magazyn Instalatora
Problemy granic przyłączy oraz instalacji wodociągowych i kanalizacyjnych. Niejasności definicji, problemy prawne. Praktyczna strona rozwiązania zagadnienia.
Sieci sensorowe wykorzystywane w monitoringu i diagnostyce obiektów trakcji elektrycznej
- Krzysztof Karwowski
- Marek Kuciński
2014
W artykule przedstawiono przegląd dostępnych systemów i standardów łączności bezprzewodowej, które mogą znaleźć zastosowanie w obszarze monitoringu i diagnostyki sieci trakcyjnej. Zaprezentowano przykładowe koncepcje i proponowane rozwiązania techniczne ze wskazaniem na kluczowe parametry mające wpływ na proces decyzyjny. Przedstawiony przegląd jest kolejną publikacją dotyczącą wykorzystania nowoczesnych technologii teleinformatycznych w szeroko rozumianej problematyce trakcyjnej.