2018 - Publications Repository - Gdańsk University of Technology

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Publications from the year 2018

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Diagnozowanie stanu retinopatii cukrzycowej przy pomocy głębokich sieci neuronowych
- Bartłomiej Jarzembiński
- Arkadiusz Kwasigroch
- Michał Grochowski
2018 Full text Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
W referacie opisano problem wykrywania oraz klasyfikacji stanu retinopatii cukrzycowej ze zdjęć dna oka przy pomocy głębokich sieci neuronowych. Retinopatia cukrzycowa jest chorobą oczu często występującą u osób z cukrzycą. Nieleczona prowadzi do uszkodzenia wzroku, a nawet ślepoty. W pracy badawczej opracowano system wykrywania retinopatii cukrzycowej na podstawie zdjęć dna oka. Opracowana sieć neuronowa przypisuje stan choroby w 5 stopniowej skali – od braku choroby do najbardziej zaawansowanego stanu choroby. Zaproponowano specjalny system kodowania klas w celu uchwycenia wielkości różnicy pomiędzy rzeczywistymi a predykowanymi stanami choroby. Uzyskano wysokie wyniki klasyfikacji na zbiorze testowym. W celu oceny skuteczności działania systemu wykorzystano miary statystyczne takie jak ważona Kappa i dokładność.
Different aspects of women’s participation in self-employment with particular reference to the costs
- Magdalena Licznerska
- Małgorzata Rembiasz
- Paulina Siemieniak
2018 Full text Ekonomiczne Problemy Usług
Over the last twenty years a growing number of researchers have been interested in female entrepreneurship. It is wort noting that being a self-employed person, for certain women, is the only chance to participate actively in social and economic life. Women choose self-employment because of flexibility of schedule and family-related reasons. This study aims to increase knowledge about self-employment as one of multiple labor market choices. The most important findings of this work concern the identification of trends, crucial topics with particular attention to the costs, and potential future research towards a better understanding of female entrepreneurship. Selected from Google Scholar and EBSCO written in Polish and English studies were classified considering different criteria: main theme, impact, country of research and year.
Different sources of market information and product innovativeness
- Dariusz Dąbrowski
2018 Full text Economics and Business Review
The purpose of this study is to identify whether the gathering of market information from different sources – i.e. from customers, competitors and other entities – is related to product innovativeness. The relationships proposed so far have not been empirically investigated but they can have important theoretical and practical implications for product innovation. To achieve the purpose of the paper data concerning 287 new products were used by applying confirmatory factor analysis and structural equation modelling. The findings indicate that the obtaining of market information from customers and market entities, other than customers and competitors, has a positive impact on product innovativeness, but there was no such relationship in the case of gathering information from competitors.
Differential Quadrature Method for Dynamic Buckling of Graphene Sheet Coupled by a Viscoelastic Medium Using Neperian Frequency Based on Nonlocal Elasticity Theory
- Mohammad Malikan
- Mohammad Sadraee Far
2018 Full text Journal of Applied and Computational Mechanics
In the present study, the dynamic buckling of the graphene sheet coupled by a viscoelastic matrix was studied. In light of the simplicity of Eringen's non-local continuum theory to considering the nanoscale influences, this theory was employed. Equations of motion and boundary conditions were obtained using Mindlin plate theory by taking nonlinear strains of von Kármán and Hamilton's principle into account. On the other hand, a viscoelastic matrix was modeled as a three-parameter foundation. Furthermore, the differential quadrature method was applied by which the critical load was obtained. Finally, since there was no research available for the dynamic buckling of a nanoplate, the static buckling was taken into consideration to compare the results and explain some significant and novel findings. One of these results showed that for greater values of the nanoscale parameter, the small scale had further influences on the dynamic buckling.
Digital Processing of Frequency–Pulse Signal in Measurement System
- Dariusz Świsulski
- Eligiusz Pawłowski
- Mykhaylo Dorozhovets
2018 Full text
The work presents the issue of the use of multichannel measurement systems of sensors processing input value to impulse signal frequency. The frequency impulse signal obtained from such sensors is often required to be processed at the same time with a voltage signal which is obtained from other sensors used in the same measurement system. In such case, it is usually necessary to sample the output signals from all sensors in the same, predetermined points in time. Sampling voltage signal by means of A/D converters is practically possible in any selected time points, and the sampling frequency–pulse signal FPS requires special algorithms. The authors present the algorithms of digital signal processing pulse frequency offline and online modes, providing the acquisition of samples at certain evenly distributed points over time.
Digits Recognition with Quadrant Photodiode and Convolutional Neural Network
- Janczyk Kamil
- Krzysztof Czuszyński
- Jacek Rumiński
2018
In this paper we have investigated the capabilities of a quadrant photodiode based gesture sensor in the recognition of digits drawn in the air. The sensor consisting of 4 active elements, 4 LEDs and a pinhole was considered as input interface for both discrete and continuous gestures. Index finger and a round pointer were used as navigating mediums for the sensor. Experiments performed with 5 volunteers allowed to record 300 examples of each digit from 0 to 9, which were drawn in the air. Digits were converted from a list of recorded coordinates into images processed as in the MNIST database. Three approaches for recognition of digits recorded by quadrant photodiode were considered: convolutional neural network trained only on examples from the MNIST database, network trained on mixed data of MNIST with examples recorded using quadrant photodiode (4/1 proportions) and trained on the MNIST with examples recorded using the elaborated sensor but after the arbitral rejection of 20% of worst quality data (4/1 proportions preserved). The application of the third approach in comparison to the first one allowed to increase the overall accuracy of digits classification from 34.4% to 86% for testing data recorded with the use of the pointer and from 32% to 81.2% for data recorded with the use of a finger (for 50Hz sampling frequency).
Dimensionally Consistent Nonlinear Muskingum Equation
- Dariusz Gąsiorowski
- Romuald Szymkiewicz
2018 JOURNAL OF HYDROLOGIC ENGINEERING
Although the Muskingum equation was proposed nearly 75 years ago, it is still a subject of active research. Despite of its simple form, the real properties of this equation have not been comprehensively explained. This paper proposes a new interpretation of the linear McCarthy’s relation. This relation can be interpreted only together with the storage equation, whereas the Muskingum equation can be derived directly from the system of equations describing the kinematic wave model. Because the Muskingum equation is a semidiscrete form of the kinematic wave equation, all typical effects which may occur in its numerical solution, such as pure translation, attenuation, and oscillations, can be comprehensively explained using the modified equation approach. Taking into account the kinematic roots of the linear Muskingum equation, its new nonlinear version is derived without using any additional McCarthy-type formula. It is shown that the proposed equation is the only correct conservative form of the nonlinear Muskingum equation which simultaneously ensures its dimensional consistency
Dimensioning of vortex storm overflows
- Jerzy Sawicki
- Szymon Mielczarek
- Szymon Mielczarek
2018 WATER SCIENCE AND TECHNOLOGY
Vortex flow control can be made as a rotational chamber, where the centrifugal force is a supporting factor. The paper presents a simplified, but experimentally verified, method of such device designing.
Direct determination of cadaverine in the volatile fraction of aerobically stored chicken breast samples
- Wojciech Wojnowski
- Justyna Płotka-Wasylka
- Kaja Kalinowska
- Tomasz Majchrzak
- Tomasz Dymerski
- Piotr Szweda
- Jacek Namieśnik
2018 Full text MONATSHEFTE FUR CHEMIE
To supplement the currently used methods for poultry meat shelf life assessment, it might be necessary to develop a technique for rapid headspace analysis of volatiles with no prior sample preparation step. Biogenic amines, in particular cadaverine, are considered meat spoilage indicators. Described in this article are the results of a preliminary investigation of the applicability of proton transfer reaction mass spectrometry in the determination of cadaverine concentration in the volatile fraction of poultry meat samples stored in aerobic conditions. Dispersive liquid–liquid microextraction–gas chromatography–mass spectrometry and determination of total viable bacteria were used as reference methods. It was determined that there is a good correlation (Pearson correlation of 0.96) between the concentration of cadaverine in the headspace of chicken meat samples stored over a period of 5 days and the total viable bacteria count. Based on the results, it can be concluded that the changes of cadaverine concentration in the meat samples’ volatile fraction can be successfully monitored with a short time of a single analysis and with no sample preparation.
Direct shear stress vs strain relation for fiber reinforced composites
- Agnieszka Sabik
2018 COMPOSITES PART B-ENGINEERING
The majority of fiber reinforced composites exhibit strong non-linear behavior in in-plane shear state. The effect is attributed to the micro-cracks appearing in the matrix and can be modeled on the micro and macro level. In this work the author proposes constitutive laws describing the non-linear in-plane shear response, which can be alternative for the relations commonly considered in the literature. The proposed equations are related to the experimental data.
Direct solid phase microextraction combined with gas chromatography – Mass spectrometry for the determination of biogenic amines in wine
- Myrsini Papageorgiou
- Dimitra Lambropoulou
- Calum Morrison
- Jacek Namieśnik
- Justyna Płotka-Wasylka
2018 Full text TALANTA.The International Journal of Pure and Applied Analytical Chemistry
A direct method based on immersion solid phase microextraction (DI-SPME) gas chromatography mass-spectrometry (GC-MS) was optimized and validated for the determination of 16 biogenic amines in Polish wines. In the analysis two internal standards were used: 1,7-diaminoheptane and bis-3-aminopropylamine. The method allows for simultaneous extraction and derivatization, providing a simple and fast mode of extraction and enrichment. Different parameters which affect the extraction procedure were studied and optimized including ionic strength (0–25%), fiber materials (PDMS/DVB, PDMS/DVD + OC, Polyacrylate, Carboxen/PDMS and DVB/CAR/PDMS) and timings of the extraction, derivatization and desorption processes. Validation studies confirmed the linearity, sensitivity, precision and accuracy of the method. The method was successfully applied to the analysis of 44 wine samples originating from several regions of Poland and 3 wine samples from other countries. Analysis showed that many of the samples contained all examined biogenic amines. The method, assessed using an Eco-Scale tool with satisfactory results, was found to be green in terms of hazardous chemicals and solvents usage, energy consumption and production of waste. Therefore the proposed method can be safely used in the wine industry for routine analysis of BAs in wine samples with a minimal detrimental impact on human health and the environment.
Discrete element method simulations of fracture in concrete under uniaxial compression based on its real internal structure
- Jan Suchorzewski
- Andrzej Tejchman-Konarzewski
- Michał Nitka
2018 INTERNATIONAL JOURNAL OF DAMAGE MECHANICS
The paper describes experimental and numerical results of concrete fracture under quasi-static uniaxial compression. Experimental uniaxial compression tests were performed on concrete cubic specimens. Fracture in concrete was detected at the aggregate level by means of three non-destructive methods: three-dimensional X-ray microcomputed tomography, two-dimensional scanning electron microscope and manual two-dimensional digital microscope. The discrete element method was used to directly simulate experiments. Concrete was modelled as a random heterogeneous four-phase material composed of aggregate particles, cement matrix, interfacial transitional zones and macrovoids based on experimental images. Two- and three-dimensional analyses were carried out. In two-dimensional analyses, the real aggregate shape was created by means of clusters of spheres. In three-dimensional calculations, spheres were solely used. A satisfactory agreement between numerical and experimental results was achieved in two-dimensional analyses. The model was capable of accurately predicting complex crack paths and the corresponding stress–strain responses observed in experiments.
Discrete-continuous optimisation of an axial flow blood pump
- Krzysztof Tesch
- Katarzyna Kaczorowska-Ditrich
2018 Full text Journal of Physics : Conference Series
This paper presents results of discrete-continuous optimisation of an axial flow blood pump. Evolution Strategies (ES) are used as a global optimisation method in order to localise the optimal solution in relatively short time. The whole optimisation process is fully automated. This also applies to geometry modelling. Numerical simulations of the flow inside the pump is performed by means of the Reynolds-Average Navier-Stokes approach. All equations are discretised by means of the finite volume method and the corresponding algebraic equation systems are solved by the open source software for CFD, namely OpenFOAM. Finally, optimisations results are presented and discussed. The objective function to be maximised is simply pressure increase. The higher pressure increase the lower angular velocities required. This makes it possible to minimise the effect of haemolysis because it is mainly caused by high shear stress which are related, among others, to angular velocities.
Discrimination of selected fungi species based on their odour profile using prototypes of electronic nose instruments
- Jacek Gębicki
- Bartosz Szulczyński
2018 MEASUREMENT
The paper presents practical application of an electronic nose technique to fast and efficient discrimination of the samples of different fungi species such as: Penicillium chrysogenum, Cladosporium herbarum, Rhizopus oryzae, Alternaria alternata. Two prototypes of electronic nose instrument were utilized for investigation of discrimination capability with respect to odour profile of these fungi: the first prototype was based on MOS-type chemical sensors, the second one was based on gas chromatography technique. The fungi samples were prepared as the aqueous suspensions, the headspace of which was subjected to analysis. The data were analysed using the multidimensional methods: PCA, LDA and k-NN. The obtained results confirmed legitimacy of application of the electronic nose technique to identification and discrimination of fungi species. In case of the gas chromatography-based electronic nose prototype correct classification of the fungi species was at the level of 80–100% depending on the classification method employed, in case of the electronic nose prototype utilizing the MOS-type sensors correct classification was at the level of 55–100%.
Discussion on “Dynamic soil-structure interaction: A three-dimensional numerical approach and its application to the Lotung case study”. Poor performance of the HSS model
- Andrzej Niemunis
- Marcin Cudny
2018 Full text COMPUTERS AND GEOTECHNICS
The Hardening Soil Small (HSS) is a constitutive model being extension to the well established Hardening Soil Model (HS) accounting for the nonlinearity of small strain stiffness. It is implemented in commercial finite element computer codes for geotechnical analyses and used widely in research and design. The article deals with a problem known as overshooting after very small load reversals. It induces much higher stiffness than prescribed by parameters. Theoretical basis of the problem as well as numerical examples are shown in the article.
Dissociative electron attachment and anion-induced dimerization in pyruvic acid
- Mateusz Zawadzki
- Milos Ranković
- Kočišek Jaroslav
- Fedor Juraj
2018 PHYSICAL CHEMISTRY CHEMICAL PHYSICS
We report partial cross sections for the dissociative electron attachment to pyruvic acid. A rich fragmentation dynamics is observed. Electronic structure calculations facilitate the identification of complex rearrangement reactions that occur during the dissociation. Furthermore, a number of fragment anions produced at electron energies close to 0 eV are observed, that cannot originate from single electron-molecule collisions. We ascribe their production to secondary reactions of the transient anions with neutral molecules. Such reactions turn out to be unusually efficient; the most probable reason for this is that they proceed via the formation of a double-hydrogen-bonded complex followed by an ultrafast proton transfer between the reaction partners.
DL_MG: A Parallel Multigrid Poisson and Poisson–Boltzmann Solver for Electronic Structure Calculations in Vacuum and Solution
- James Womack
- Lucian Anton
- Jacek Dziedzic
- Phil Hasnip
- Matt Probert
- Chris-Kriton Skylaris
2018 Full text Journal of Chemical Theory and Computation
The solution of the Poisson equation is a crucial step in electronic structure calculations, yielding the electrostatic potential -- a key component of the quantum mechanical Hamiltonian. In recent decades, theoretical advances and increases in computer performance have made it possible to simulate the electronic structure of extended systems in complex environments. This requires the solution of more complicated variants of the Poisson equation, featuring nonhomogeneous dielectric permittivities, ionic concentrations with nonlinear dependencies, and diverse boundary conditions. The analytic solutions generally used to solve the Poisson equation in vacuum (or with homogeneous permittivity) are not applicable in these circumstances, and numerical methods must be used. In this work, we present DL_MG, a flexible, scalable, and accurate solver library, developed specifically to tackle the challenges of solving the Poisson equation in modern large-scale electronic structure calculations on parallel computers. Our solver is based on the multigrid approach and uses an iterative high-order defect correction method to improve the accuracy of solutions. Using two chemically relevant model systems, we tested the accuracy and computational performance of DL_MG when solving the generalized Poisson and Poisson−Boltzmann equations, demonstrating excellent agreement with analytic solutions and efficient scaling to ~10^9 unknowns and 100s of CPU cores. We also applied DL_MG in actual large-scale electronic structure calculations, using the ONETEP linear-scaling electronic structure package to study a 2615 atom protein−ligand complex with routinely available computational resources. In these calculations, the overall execution time with DL_MG was not significantly greater than the time required for calculations using a conventional FFT-based solver.
Długie pociągi
- Eligiusz Mieloszyk
2018
Wskazano, że przy wprowadzaniu długich pociągów pojawiają się możliwości, ale i ograniczenia różnej natury oraz problemy do rozwiązania. Inne w przypadku długich pociągów i inne w przypadku ciężkich pociągów. Pokazano długie pociągi, jako szansę na polepszenie bezpieczeństwa na drogach, poprzez ograniczenie na nich ruchu samochodów ciężarowych. Łatwiej będzie w praktyce realizować pomysł „Tiry na tory” Długie pociągi są szansą na zmniejszeni kosztów przewozów towarowych i zmniejszenie zajętości torów. Gdzie w składzie pociągu umieścić lokomotywy? Pokazano znaczenie metod i metodyki prowadzenia długich pociągów, w tym znaczenie i wpływ siły pociągowej oraz siły hamowania na nawierzchnię kolejową i bezpieczeństwo jazdy. Zwiększenie oddziaływań cyklicznych na tor w przypadku długich pociągów i ich ewentualny wpływ na degradację toru. Do analizy wybranych zagadnień wykorzystano uogólnione układy dynamiczne i nieklasyczny rachunek operatorów
DNA methylation as a mediator of HLA-DRB1*15:01 and a protective variant in multiple sclerosis
- Lara Kular
- Yun Liu
- Sabrina Ruhrmann
- Galina Zheleznyakova
- Francesco Marabita
- David Gomez-Cabrero
- Tojo James
- Ewoud Ewing
- Magdalena Lindén
- Bartosz Górnikiewicz
- Shahin Aeinehband
- Pernilla Stridh
- Jenny Link
- Till Andlauer
- Christiane Gasperi
- Heinz Wiendl
- Frauke Zipp
- Ralf Gold
- Björn Tackenberg
- Frank Weber
- Bernhard Hemmer
- Konstantin Strauch
- Stefanie Heilmann-Heimbach
- Rajesh Rawal
- Ulf Schminke
- Carsten Schmidt
- Tim Kacprowski
- Andre Franke
- Matthias Laudes
- Alexander Dilthey
- Elisabeth Celius
- Helle Søndergaard
- Jesper Tegnér
- Hanne Harbo
- Annette Oturai
- Sigurgeir Olafsson
- Hannes Eggertsson
- Bjarni Halldorsson
- Haukur Hjaltason
- Elias Olafsson
- Ingileif Jonsdottir
- Kari Stefansson
- Tomas Olsson
- Fredrik Piehl
- Tomas Ekström
- Ingrid Kockum
- Andrew Feinberg
- Maja Jagodic
2018 Full text Nature Communications
The human leukocyte antigen (HLA) haplotype DRB1*15:01 is the major risk factor for multiple sclerosis (MS). Here, we find that DRB1*15:01 is hypomethylated and predominantly expressed in monocytes among carriers of DRB1*15:01. A differentially methylated region (DMR) encompassing HLA-DRB1 exon 2 is particularly affected and displays methylation-sensitive regulatory properties in vitro. Causal inference and Mendelian randomization provide evidence that HLA variants mediate risk for MS via changes in the HLA-DRB1 DMR that modify HLA-DRB1 expression. Meta-analysis of 14,259 cases and 171,347 controls confirms that these variants confer risk from DRB1*15:01 and also identifies a protective variant (rs9267649, p < 3.32 × 10-8, odds ratio = 0.86) after conditioning for all MS-associated variants in the region. rs9267649 is associated with increased DNA methylation at the HLA-DRB1 DMR and reduced expression of HLA-DRB1, suggesting a modulation of the DRB1*15:01 effect. Our integrative approach provides insights into the molecular mechanisms of MS susceptibility and suggests putative therapeutic strategies targeting a methylation-mediated regulation of the major risk gene.
Do global brands contribute to the economy of their country of origin? A dynamic spatial approach
- Wioleta Kucharska
- Karol Flisikowski
- Ilenia Confente
2018 Full text Journal of Product & Brand Management
Purpose - Brand positioning based on the brand’s country of origin is at the centre of attention in international marketing. It is evident that global brands constitute critical intangible assets for businesses and places. However, it is not clear how they contribute to national economies. This paper aims to discuss the significance of brands as contributing to the value of their companies but also helping to leverage national economies. Although global brands can be produced and purchased in multiple countries, their influence on the economy of the country where their owner’s seat is located can be more meaningful than in other economies included in the “global factory”. Design/methodology/approach - Based on 500 Brandirectory, the Most Valuable Global Brands 2011-2015 rankings powered by Brand Finance, the authors observed a spatial-economic autocorrelation which exemplifies the potential interdependency between gross domestic product (GDP) and brand value. This relationship has become a starting point for designing a spatial regression model. Findings - The findings support the hypothesis that assumptive spatial dependencies have a significant influence on the examined relationship of brand value and GDP. Originality/value - The presented study is the first to examine the potential interdependence between brand values and GDP of the countries of origin using a dynamic spatial approach.