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Gdańsk University of Technology

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Publications from the year 2018

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  • Selection of Features for Multimodal Vocalic Segments Classification
    • Szymon Zaporowski
    • Andrzej Czyżewski
    2018

    English speech recognition experiments are presented employing both: audio signal and Facial Motion Capture (FMC) recordings. The principal aim of the study was to evaluate the influence of feature vector dimension reduction for the accuracy of vocalic segments classification employing neural networks. Several parameter reduction strategies were adopted, namely: Extremely Randomized Trees, Principal Component Analysis and Recursive Parameter Elimination. The feature extraction process is explained, applied feature selection methods are presented and obtained results are discussed

  • Selection of main engines for hopper suction dredgers with the use oobability models
    • Damian Bocheński
    2018 Full text Polish Maritime Research

    This paper presents a new original method of selection of main engines for hopper suction dredgers with regard to probabilistic models. It was proposed to use the normal distribution to describe the operational loads of the main receivers. The principles for determination of parameters of load distribution and design power of the main engines were formulated. Lastly, the principles of selection of the size and number of main engines has been proposed.

  • Selection of material for X-ray tomography analysis and DEM simulations: comparison between granular materials of biological and non-biological origins
    • Laurent Babout
    • Krzysztof Grudzień
    • J Wiącek
    • Maciej Niedostatkiewicz
    • Bartłomiej Karpiński
    • Marek Szkodo
    2018 Full text GRANULAR MATTER

    Physical properties and X-ray tomography images of five different granular materials: glass bead, glass grit, short grain white rice, sorghum and clay granules (Seramis) are investigated to select the most promising materials for numerical simulations and time-lapse X-ray tomography imaging. The examined materials represent granular materials of non-biological origin (glass bead, glass grit and Seramis) and granular plant materials (rice and sorghum). The choice of materials was dictated by their mechanical and packing properties, on one hand, and 3D imaging qualities of granular materials and quantitative particle shape analysis, on the other hand. It was found that materials of biological origin, i.e. rice and sorghum, showed promising characteristics and may be considered as the most appropriate materials for comparison between time-lapse X-ray tomography experiments and numerical simulation.

  • Selfish Attacks in Two-Hop IEEE 802.11 Relay Networks: Impact and Countermeasures
    • Jerzy Konorski
    • Szymon Szott
    2018 Full text IEEE WIRELESS COMMUNICATIONS LETTERS

    In IEEE 802.11 networks, selfish stations can pursue a better quality of service through selfish MAC-layer attacks. Such attacks are easy to perform, secure routing protocols do not prevent them, and their detection may be complex. Two-hop relay topologies allow a new angle of attack: a selfish relay can tamper with either source traffic, transit traffic, or both. We consider the applicability of selfish attacks and their variants in the two-hop relay topology, quantify their impact, and study defense measures.

  • Self-organized multilayered graphene-boron doped diamond hybrid nanowalls for high performance electron emission devices
    • Kamatchi J Sankaran
    • Mateusz Ficek
    • Srinivasu Kunuku
    • Panda Kalpataru
    • Chien-Jui Yeh
    • Jeong Park
    • Miroslaw Sawczak
    • Piotr Michałowski
    • Keh-Chyang Leou
    • Robert Bogdanowicz
    • I-Nan Lin
    • Ken Haenen
    2018 Full text NANOSCALE

    Carbon nanomaterials like nanotubes, nanoflakes/nanowalls and graphene have been used as electron sources due to their superior field electron emission (FEE) characteristics. Nevertheless, these materials show poor stability and a short lifetime, preventing them from being used in practical device applications. The intention of this study was to find an innovative nanomaterial, possessing both high robustness and reliable FEE behavior. A hybrid structure of self-organized multilayered graphene (MLG)boron doped diamond (BDD) nanowall materials with superior FEE characteristics are successfully synthesized using a microwave plasma enhanced chemical vapor deposition process. Transmission electron microscopy reveals that the carbon clusters thus prepared are of uniform, dense and sharp nanowall morphology with sp3 diamond cores encased by an sp2 MLG shell. Detailed nanoscale investigations by peak force-controlled tunneling atomic force microscopy show that each of the core-shell structured carbon clusters field emits electrons equally well. The MLG-BDD nanowall materials show a low turn-on field of 2.4 V/μm, a high emission current density of 4.2 mA/cm2 at an applied field of 4.0 V/μm, a large field enhancement factor of 4500 and prominently high lifetime stability lasting for 700 min, enlightening their superiority on comparison with other hybrid nanostructured materials. The potential in practical device applications for these MLG-BDD hybrid nanowall materials is further illustrated by the plasma illumination behavior of a microplasma device, which used these materials as cathode, where low threshold voltage of 330 V (low threshold field of 330 V/mm) and long plasma stability of 358 min are demonstrated. The fabrication of these hybrid nanowalls is straight forward and thereby opens up a pathway for the advancement in next generation cathode materials for high brightness electron emission and microplasma-based display devices.

  • Semantic Analysis and Text Summarization in Socio-Technical Systems
    • Nina Rizun
    2018

    In this chapter the authors present the results of the development the methodology for increasing the reliability of the functioning of the Socio-Technical System. The existed methods and algorithms for processing unstructured (textual) information were studied. Taking into account noted above strengths and weaknesses of Discriminant and Probabilistic approaches of Latent Semantic Relations analysis in of the summarization projection the Methodology of Two-level Text Summarization Based on the Latent Semantic Relations was developed. During developing and testing this methodology authors proved, that the combination of the discriminant and probabilistic methods gives the opportunity to improve the text summarization quality by using the synergistic effect of semantic approaches and latent relations identification as well as algorithms for prediction of random processes. This effect was achieved via increasing: the quality of grouping (clustering) of fragments of the original analyzed text (paragraphs or sentences) by using a complex application of LDA-method recognizing taking account the hidden latent semantic relations phenomena; the quality of text summarization process by using a complex application latent semantic analysis taking account the optimal number of probabilistic topics. The examples of the proposed Methodology realization were presented. Formation of this kind of summary could help to human as an element of Socio-Technical System to increase the speed of processing the big amount of information (for example, realization the procedure of monitoring and analysis the daily or retrospective documents, as well as supporting the making-decision processes).

  • Semantic modeling of contextual augmented reality environments
    • Dariusz Rumiński
    2018 Full text

    Despite significant progress in the field of augmented reality (AR), regarding both hardware and software, there is still a lack of universal models and methods that would enable building ubiquitous AR systems that could be used anywhere and anytime, covering different application areas. This dissertation describes a new approach to building AR systems, called the Contextual Augmented Reality Environment (CARE). The CARE approach is based on contextual selection of both the real objects to be augmented and the synthetic augmentation content. Due to the use of context – understood as the location, time, user's preferences and capabilities of the device – the problem of simultaneous tracking of multiple real objects and the problem of applying synthetic augmentation content is significantly reduced. In a given context, only the objects assigned to a given context range, and which are of interest to a user, are tracked and augmented. In the CARE approach, AR presentations are built in real time based on the context by combining resources provided by different entities in a distributed environment. A semantic approach is used to describe the context and the distributed AR environment. The CARE approach consists of four elements: the CARE Architecture of Semantic AR Services, the Semantic Augmented Reality Ontology for modeling CARE environments, the Semantic Discovery and Matching Method for searching and combining AR components in CARE environments, and the Contextual Augmented Reality Language (CARL) for representing contextual AR presentations. In the dissertation, a prototype implementation of the CARE system based on a service-oriented architecture is described and a thorough qualitative and quantitative evaluation is presented. The results of the evaluation indicate that the CARE approach enables efficient modeling of large-scale contextual augmented reality environments.

  • Sensitivity analysis based on non-intrusive regression-based polynomial chaos expansion for surgical mesh modelling
    • Katarzyna Szepietowska
    • Benoit Magnain
    • Izabela Lubowiecka
    • Eric Florentin
    2018 Full text STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION

    The modelling of a system containing implants used in ventral hernia repair and human tissue suffers from many uncertainties. Thus, a probabilistic approach is needed. The goal of this study is to define an efficient numerical method to solve non-linear biomechanical models supporting the surgeon in decisions about ventral hernia repair. The model parameters are subject to substantial variability owing to, e.g., abdominal wall parameter uncertainties. Moreover, the maximum junction force, the quantity of interest which is worthy of scrutiny due to hernia recurrences, is non-smooth. A non-intrusive regression-based polynomial chaos expansion method is employed. The choice of regression points is crucial in such methods, thus we study the influence of this choice on the quantity of interest, and look for an efficient strategy. For this purpose, several aspects are studied : (i) we study the quality of the quantity of interest, i.e. accuracy of the mean and standard deviation, (ii) we perform a global sensitivity analysis using Sobol sensitivity indices. The influence of uncertainties of the chosen variables is presented. This study leads to the definition of an efficient numerical simulation dedicated to our model of implant.

  • Sensitivity analysis in design process of sandwich U-shaped composite footbridge
    • Tomasz Ferenc
    • Łukasz Pyrzowski
    • Jacek Chróścielewski
    • Tomasz Mikulski
    2018

    The structure of the sandwich composite footbridge of a 14 metre span length and U-shaped cross-section was analysed. Sensitivity analysis was performed to support the design process of this innovative object. Linear discrete sensitivity analysis was performed by means of finite element method. The influence of vari-ation of several design variables i.e. thicknesses of inner and outer laminates on the mid-span deflection, as-sumed as state variable, was investigated. Three structural models were analysed assuming the laminate made of isotropic material (IZO1), orthotropic material (ORTO1) and orthotropic six layered material (OR-TO6). The results were presented graphically comparing sensitivity analysis with parametric analysis.

  • Separation of toluene from gas phase using supported imidazolium ionic liquid membrane
    • Iwona Cichowska-Kopczyńska
    • Monika Joskowska
    • Bartosz Dębski
    • Robert Aranowski
    • Jan Hupka
    2018 JOURNAL OF MEMBRANE SCIENCE

    Investigation on utilization of supported ionic liquids membranes for hydrocarbon separation from the gas phase was performed. Properties of membrane phase, wettability of supports, swelling effects and solubility of toluene were taken into account. Toluene permeation rates were significantly higher than those of pure nitrogen, the selectivity in a range of 17–341 was satisfying for separation. Despite the increase of viscosity resulting from increasing alkyl chain length of imidazolium bis(trifluoromethylsulfonyl)imide [Tf2N] ionic liquids, permeation of toluene increases due to the higher hydrophobicity and therefore separation is solubility-controlled. However, imidazolium trifluoromethanesulfone [TfO] ionic liquids did not follow the same path. Nevertheless, toluene was successfully separated from N2/toluene gas stream using ionic liquid membranes based on both [Tf2N] and [TfO] yet, in the light of the obtained results and literature data these systems are highly recommended for VOCs separation from gas phase.

  • Serum bisphenol A concentrations correlate with serum testosterone levels in women with polycystic ovary syndrome
    • Aleksandra Konieczna
    • Dominik Rachoń
    • Katarzyna Owczarek
    • Paweł Kubica
    • Agnieszka Kowalewska
    • Błażej Kudłak
    • Andrzej Wasik
    • Jacek Namieśnik
    2018 Full text REPRODUCTIVE TOXICOLOGY

    The aim of this study was to determine serum bisphenol A (BPA) concentrations using high performance liquid chromatography with tandem mass spectrometry (HPLC–MS/MS) in women with polycystic ovary syndrome (PCOS) (n=106, age range 18–40 yrs) and to evaluate its potential impact on their hormonal and metabolic profile. The control group consisted of age- and BMI-matched 80 eumenorrheic women with no clinical or biochemical hyperandrogenism. Our results showed that women with PCOS had significantly higher serum BPA concentrations than healthy controls (geometric mean and [95% CI]: 0.202 ng/mL [0.150; 0.255] vs. 0.154 ng/ mL [0.106; 0.201], P=0.035), which correlated positively with serum total testosterone (TST) (R=0.285, P=0.004) and the free androgen index (FAI) (R=0.196, P=0.049). There were no significant correlations between serum BPA and BMI, waist circumference, serum glucose, insulin and lipids. These results point to the potential role of BPA in the pathogenesis of the ovarian hyperandrogenism in women with PCOS.

  • Shape-dependent enhanced photocatalytic effect under visible light of Ag3PO4 particles
    • Julia Zwara
    • Ewelina Grabowska
    • Tomasz Klimczuk
    • Wojciech Lisowski
    • Adriana Zaleska-Medynska
    2018 JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY

    Silver phosphate (Ag3PO4) could be considered as visible light induced photocatalyst for pollutants degradation, due to its narrow band gap (∼2.4 eV). However, Ag3PO4 photoactivity depends on surface properties and synthesis route. In this study, differently shaped Ag3PO4 photocatalysts have been synthesized through the precipitation, ion exchange, soft-chemical or hydrothermal method. To correlate surface properties with photoactivity all samples were characterized towards morphology, crystal structure, specific surface area, optical properties, chemical composition and activity in phenol degradation upon visible light irradiation (λ > 420 and 455 nm). It is worthwhile noting that the most active Ag3PO4 samples possessed almost the same activity in phenol degradation upon irradiation from visible range (λ > 455 nm) that P25 TiO2 upon UV light. Phenol degradation rate equaled to 3.31 and 3.23 μmol/dm3/min in the presence of branched and rhombic dodecahedral Ag3PO4 particles, while it reached 3.36 μmol/dm3/min in the presence of P25 and UV light. Analysis of the degradation intermediates indicated that the benzoquinone was the primary byproducts of phenol degradation. Scavengers-assisted photocatalytic test confirmed that mainly %O2 − has been involved in phenol degradation under visible radiation. Surface composition analysis by XPS suggested that higher total silver content favors photoactivity, while higher ratio of Ag0 to Ag+ suppress photoactivity. Long term photocatalytic tests also implies that increase in Ag0 amount at the Ag3PO4 surface, due to photoreduction of Ag ions, rusulted in activity drop.

  • Share of the wage factor in national income – selected aspects
    • Małgorzata Gawrycka
    • Anna Szymczak
    2018

    The aim of this study is to examine changes in the share of the wage factor in national income, in selected EU countries against labour productivity and investment rates reflecting changes in capital-labour relations, indicated by researchers as determinants of change of the share of the wage factor in national income. The scope of the study includes a review of literature devoted to the issue of wage factor share in national income and the empirical part related to this issue. The study used elements of descriptive statistics and the method of induction. The results of the study show that in the years 2005–2015 a decrease in the share of the wage factor in national income was observed in Poland, Hungary and Spain. In the case of the Czech Republic, Slovakia, Germany and France, the share of the wage factor in national income has increased. What is more, the conclusions from previous research regarding the impact of financial crises on reducing the share of wages in national income have not been confirmed. In the majority of the countries surveyed, the financial crisis did not contribute to such changes. It cannot be clearly stated that there is a connection between labour productivity, investment rate and the share of the wage factor in national income.

  • Shared processor scheduling
    • Dariusz Dereniowski
    • Wiesław Kubiak
    2018 Full text JOURNAL OF SCHEDULING

    We study the shared processor scheduling problem with a single shared processor to maximize total weighted overlap, where an overlap for a job is the amount of time it is processed on its private and shared processor in parallel. A polynomial-time optimization algorithm has been given for the problem with equal weights in the literature. This paper extends that result by showing an (log)-time optimization algorithm for a class of instances in which non-decreasing order of jobs with respect to processing times provides a non-increasing order with respect to weights—this instance generalizes the unweighted case of the problem. This algorithm also leads to a 1/2-approximation algorithm for the general weighted problem. The complexity of the weighted problem remains open.

  • Shell model of multiple-row moment I-section end-plate joint
    • Krzysztof Żółtowski
    • Przemysław Kalitowski
    2018

    The paper deals with a problem of application of shell elements in the models of multiple-row moment end-plate connections. The extended connection of I-section with a cross-section W760x265x220 made of steel S355 was analyzed. Comparison analysis of FEM, complex volume and shell models has been done. Three cases with different end-plate thickness: 14, 18 and 36 mm were analyzed and compared with the reference results. Comparison of the forces in bolts shows that simplification of the model from volume to shell elements does not greatly affect the distribution of forces in bolts. The presented analysis shows that a relatively simple shell model can be sufficient in the design of multiple-row moment end-plate joints.

  • Ship domain applied to determining distances for collision avoidance manoeuvres in give-way situations
    • Rafał Szłapczyński
    • Przemysław Krata
    • Joanna Szłapczyńska
    2018 OCEAN ENGINEERING

    Ship domain is often used in marine navigation and marine traffic engineering as a safety condition. The basic idea behind those applications is that an encounter of two or more ships can be considered safe if neither of ship domains is intruded by other ships. Research utilising this approach has been documented in numerous works, including publications on optimising collision avoidance manoeuvres performed to fulfil domain-based safety conditions. However, up to this point there has been no method, which would apply ship's domain to determine the last moment when a particular collision avoidance manoeuvre can still be successfully performed. This issue is addressed here. The proposed method uses a model of ship's dynamics to assess the time and distance necessary for a manoeuvre resulting in avoiding domain violations in give-way situations. The model and the method are described in detail and illustrated in a series of simulation results. The simulations cover full spectrum of typical give-way encounters in various circumstances: head-on, crossing and overtaking situations; manoeuvres limited to course alteration and those combining turns with speed reduction; open or confined waters and finally – in good and restricted visibility.

  • Ship weather routing optimization with dynamic constraints based on reliable synchronous roll prediction
    • Przemysław Krata
    • Joanna Szłapczyńska
    2018 OCEAN ENGINEERING

    Ship routing process taking into account weather conditions is a constrained multi-objective optimization problem and it should consider various optimization criteria and constraints. Formulation of a stability-related, dynamic route optimization constraint is presented in this paper. One of the key objectives of a cross ocean sailing is finding a compromise between ship safety and economics of operation. This compromise should be taken into account by the planning procedure and proper optimization algorithm. In this research complex stability-related phenomena are adopted as the basis for the constraint set formulation in weather routing. Thus, the synchronous roll, parametric resonance, surf riding and broaching-to are considered according to the IMO MSC.1/Circ.1228 guidance. However, the dangerous resonance motion of the ship depends on her natural period of roll and a degree of tuning to the encounter wave period. This natural period strictly depends on the GZ curve shape and, consequently, on the amplitude of roll. In order to properly model the natural period of roll, a new method utilizing equivalent metacentric height is applied and incorporated into the route optimization. Sample calculations of the cross ocean routes are presented and the effect of the dynamic approach to the constraint set is demonstrated and discussed.

  • Shipping Safety Management on Polish Inland Waterways
    • Patrycja Jerzyło
    • Paulina Rekowska
    • Kujawski Artur
    2018 Archives of Transport System Telematics

    Over the past years, the role of inland waterway transport has increased compared to other modes of transport. The increasing intensity of the inland vessel traffic significantly affects the safety of navigation. The article analyses the main causes of accidents and incidents that occurred on the Odra Waterway and Lower Vistula. The authors have classified those accidents and suggested possible directions for the development of inland waterway management in order to improve its efficiency. Navigationally critical areas in the lower section of the rivers Odra and Vistula have been indicated. These areas should be taken into account in long-term planning of the inland shipping development to ensure transport safety.

  • Shub’s conjecture for smooth longitudinal maps of S^m
    • Grzegorz Graff
    • Michał Misiurewicz
    • Piotr Nowak-Przygodzki
    2018 JOURNAL OF DIFFERENCE EQUATIONS AND APPLICATIONS

    Let f be a smooth map of the m-dimensional sphere Sm to itself, preserving the longitudinal foliation. We estimate from below the number of fixed points of the iterates of f , reduce Shub’s conjecture for longitudinal maps to a lower dimensional classical version, and prove the conjecture in case m = 2 and in a weak form for m = 3.

  • Signal filtering method of the fast-varying diesel exhaust gas temperature
    • Patrycja Puzdrowska
    2018 Full text Combustion Engines

    The paper presents the problem of the impact of external distortions originating on laboratory test stands on the results of measurements of fast-varying diesel exhaust gas temperature. It has been stressed how significant the aspect of the test stand adaptation is during an experiment to ensure the smallest possible impact. This paper, however, focuses on the methods of mathematical processing of a signal recorded during experimental research of a real object. The most significant parameter requiring filtering is the fast-varying exhaust gas temperature in the engine exhaust channel. Methods of mathematical processing adequate to this type of distorted signal have been presented, particularly those that can be used in the Matlab environment and consisting in averaging of the obtained curves of temperature changes. The results of the application of these methods have also been presented on actual curves recorded during laboratory tests and their evaluation has been made.