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Gdańsk University of Technology

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Publications from the year 2018

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  • Cognition and Decisional Experience to Support Safety Management in Workplaces
    • Caterine De
    • Cesar Sanin
    • Edward Szczerbicki
    2018 Advances in Intelligent Systems and Computing

    Hazards are present in all workplaces and can result in serious injuries, short and long-term illnesses, or death. In this context, management of safety is essential to ensure the occupational health of workers. Aiming to assist the safety management process, especially in industrial environments, a Cognitive Vision Platform for Hazard Control (CVP-HC) is proposed. This platform is a Cyber Physical system, capable of identifying critical safety behaviors overcoming the limitations of current computer vision systems. In addition, the system stores experiential knowledge about safety events in an explicit and structured way. This knowledge can be easily accessed and shared and may be used to improve the user/company experience as well as to understand the company safety culture and to support a long term change process. The CVP-HC is a scalable yet adaptable system capable of working in a variety of video analysis scenarios whilst meeting specific safety requirements of companies by modifying its behavior accordingly. The proposed system is based on the Set of Experience Knowledge Structure (SOEKS) and Decisional DNA (DDNA).

  • COLD CRACKING OF S460N STEEL WELDED IN WATER ENVIRONMENT
    • Jacek Tomków
    • Jerzy Łabanowski
    • Dariusz Fydrych
    • Grzegorz Rogalski
    2018 Full text Polish Maritime Research

    This paper shows results of weldability testing of fine-grained high -strength low- alloy S460N steel welded in water environment by covered electrodes. The tests were carried out by using the CTS test specimens with fillet welds. Four specimens were welded under water and one specimen in air. Welded joints were subjected to non-destructive visual and penetration tests. The accepted joints were then subjected to macroscopic and microscopic inspection and Vickers hardness measurements as well. The experiments showed that S460N steel welded in water environment is characterized by a high susceptibility to cold cracking.

  • Collaborative Exploration of Trees by Energy-Constrained Mobile Robots
    • Shantanu Das
    • Dariusz Dereniowski
    • Christina Karousatou
    2018 THEORY OF COMPUTING SYSTEMS

    We study the problem of exploration of a tree by mobile agents (robots) that have limited energy. The energy constraint bounds the number of edges that can be traversed by a single agent. We use a team of agents to collectively explore the tree and the objective is to minimize the size of this team. The agents start at a single node, the designated root of the tree and the height of the tree is assumed to be less than the energy bound B of the agents. The agents have local vision and communication capabilities; two agents can exchange information only when they are collocated at the same node. We provide an exploration algorithm for visiting all nodes of the unknown tree and we compare our algorithm with the optimal offline algorithm that has complete knowledge of the tree. Our algorithm has a competitive ratio of O(log B), independent of the number of nodes in the tree. We also show that this is the best possible competitive ratio for exploration of unknown trees.

  • Combined extraction and microextraction techniques: Recent trends and future perspectives
    • Justyna Płotka-Wasylka
    • Muhammad Sajid
    2018 Full text TRAC-TRENDS IN ANALYTICAL CHEMISTRY

    The latest advancements in the analytical sample preparation indicate a trend of combining different extraction techniques with targeting an improvement in separation, cleanup, detection limits, enrichment factors, and dealing with complex matrices. This manuscript identifies mainly two groups of combined sample preparation techniques. The first group integrates conventional or enhanced extraction techniques with microextraction. The second group combines microextraction with each other. The objectives and merits of each combination are critically appraised with respect to nature of the samples, analytical figure of merits, and certain application scenarios. Green aspects of combined extraction methods are described with some examples. At the end, a brief account is provided on accomplishments, limitations, and future directions.

  • Combining X-ray tomogrpahy imaging and DEM simulations to investigate granular material flow during silo discharging
    • Konrad Miśkiewicz
    • Maciej Niedostatkiewicz
    • Krzysztof Grudzień
    • Babout Laurent
    2018

    Even after few decades of research, the study of particle motion taking place during silo discharging hasn’t been fully addressed, both experimentally and numerically, because of nontrivial behaviors that occur during associated flow patterns. For instance, discrete element method (DEM) has shown good qualitative prediction potential of velocity profile, but, on the other hand, frequently failed to match quantitatively experimental measurements, especially close to the outlet. This could have different reasons: bad choice of granular materials property, initial packing that does not fully agree with experimental conditions or the physical/mechanical laws assumed to govern the flow. The main scope of this paper is to compare experimental results with DEM simulations performed in the Yade framework, in the case where the sources of uncertainty during modeling have been reduced as much as possible. Particularly, initial packing of particles in silo discharging simulation has been obtained by image processing of X-Ray tomography imaging data to create a structural faithful model. All measurements have concerned different types of granular material, i.e. glass spheres, rice and sorghum mixed with tracer particles of similar physical properties but different shapes (i.e. glass grit, sorghum and rice, respectively). In that way, the comparison at different discharging times between DEM simulation and time-lapse X-ray tomography measurements can focus on evaluations of particle behaviors at the level of the closest neighborhood of tracer particles.

  • Comment on "Measurements without probabilities in the final state proposal"
    • Eliahu Cohen
    • Marcin Nowakowski
    2018 Full text PHYSICAL REVIEW D

    The final state proposal [G.T. Horowitz and J.M. Maldacena, J. High Energy Phys.2004(2),8 (2004)] is an attempt to relax the apparent tension betweenstring theory and semiclassicalarguments regarding the unitarity of black hole evaporation. The authors of [R. Bousso and D.Stanford, Phys. Rev. D89, 044038 (2014)] analyze thought experiments where an infalling observerfirst verifies the entanglement between early and late Hawking modes and then verifies the interiorpurification of the same Hawking particle. They claim that “probabilities for outcomes of thesemeasurements are not defined” and therefore suggest that “the final state proposal does not offera consistent alternative to the firewall hypothesis.” We show, in contrast, that one may define allthe relevant probabilities based on the so-called ABL rule [Y. Aharonov, P.G. Bergmann, and J.L.Lebowitz, Phys. Rev.134, 1410 (1964)], which is better suited for this task than the decoherencefunctional. We thus assert that the analysis of Bousso and Stanford cannot yet rule out the finalstate proposal.

  • Communication: Inside the water wheel: Intrinsic differences between hydrated tetraphenylphosphonium and tetraphenylborate ions
    • Mateusz Leśniewski
    • Maciej Śmiechowski
    2018 Full text JOURNAL OF CHEMICAL PHYSICS

    Tetraphenylphosphonium tetraphenylborate (TPTB) is a common reference electrolyte in physical chemistry of solutions allowing for a convenient partitioning of thermodynamic properties into single-ion contributions. Here, we compute on the basis of ab initio molecular dynamics simulations the infrared (IR) spectra for hydrated constituent ions of the TPTB assumption. Using spectral decomposition techniques, we extract important information pertaining to the state of the hydration water from the IR spectra. Within their physical radii, the ions manage to capture about a dozen H2 O molecules, several of which penetrate deep into the grooves between the tetrahedrally oriented “sails” of the rotating ions. In accordance with previous IR and Raman experiments, we find a considerable blue shift of the νOH stretching band of liquid water by 240 cm−1 for TB, due to the extensive O–H···π hydrogen bonding, which is much weaker for TP. On the other hand, both ions show a second prominent band in the νOH vibration range, only mildly blue shifted with respect to bulk water and attributable to the general distortion of the hydrogen bond network of the neighboring solvent. Finally, spatially resolved IR spectra allow us to pinpoint the exact location around the solutes, from which different IR resonances of the solvent originate.

  • Community of Practice for Product Innovation Towards the Establishment of Industry 4.0
    • Mohammad Waris
    • Cesar Sanin
    • Edward Szczerbicki
    2018

    The aim of this paper is to present the necessity of formulating the Community of Practice for Product Innovation process based on Cyber-Physical Production Systems towards the establishment of Industry 4.0. At this developing phase of Industry 4.0, there is a need to define a clear and more realistic approach for implementation process of Cyber-Physical Production Systems in manufacturing industries. Today Knowledge Management is considered as the next arena of global competition. One of the most promising areas where Knowledge Management is studied and applied is product innovation. This paper explains the efficient and systematic methodology for Knowledge Management through Community of Practice for product innovation, thus connecting manufacturing units at global level.

  • Community Road Safety Strategies in the Context of Sustainable Mobility
    • Miroslava Mikusova
    • Joanna Żukowska
    • Adam Torok
    2018

    The paper presents an overview on the road safety strategies and action plans implemented in the framework of the “SOL - Save our lives: Comprehensive road safety strategy for Central Europe” project. It contains summarization of learned knowledge regarding the efficiency of measures applied and highlights examples of good practices. The purpose of the paper is to provide recommendations for effective and successful planning, formulation and implementation of road safety strategies at community level and also propose a systematic approach for their assessment in the context of sustainable mobility.

  • Comparative analysis of different numerical models of a steel radial gate
    • Krzysztof Brusewicz
    • Robert Jankowski
    2018 Full text MATEC Web of Conferences

    Hydrotechnical structures are important components in water management system and general flooding safety. Their reliability should be ensured since potential damage might lead to catastrophic consequences. Weir gates are considered to be highly vulnerable elements of each hydro power plant, with regard to its dynamic resistance. The aim of the paper is to compare different numerical models and their influence on the results of a computational modal analysis of a steel radial gate. The investigation has been conducted for models using beam and shell elements, while assuring the same geometry, material properties and boundary conditions. The results of the comparative computational analysis indicate that the eigenmode shapes are similar for both models, while the corresponding eigenfrequencies are considerably different. These differences are important from the point of view of dynamic analysis, especially that the first eigenfrequency falls within the energy range typical for earthquakes and mining tremors.

  • COMPARATIVE ANALYSIS OF POINT CLOUDS OBTAINED BY TLS AND PHOTOGRAMMETRY
    • Tadeusz Widerski
    • Karol Daliga
    • Dominika Chorąży
    2018

    Technical progress in the field of 3D modelling resulted in increasing use of such technics to create a virtual 3D models of objects. Three-dimensional spatial models are used in a wide range of applications such as inventorisation of architectural-construction, an inventorisation of archaeological sites, medicine and wide-known engineering. Spatial models are created based on the point clouds acquired with laser scanners or photogrammetry. Each of these data acquiring methods has its advantages, limitations and accuracy possible to obtain. For this reason, laser scanning and photogrammetry can be used for a variety of applications, although there are also areas where both methods work well. In areas where laser scanning and photogrammetry can be applied equally (accuracy and reliability of measurement results are at assumed level) a factor influencing choice of measurement technology, in most cases, is cost of the measuring apparatus and cost of measurement. This article is included comparative analysis of the data in the form of a point cloud obtained with the use of terrestrial laser scanning (TLS) and close-range photogrammetry baser on images obtained from nonmetric digital camera. The test objects were inside surfaces of towers walls of Wisloujscie Fortress in Gdansk (Poland).

  • Comparative analysis of spectral and cepstral feature extraction techniques for phoneme modelling
    • Grazina Korvel
    • Olga Kurasova
    • Bożena Kostek
    2018

    Phoneme parameter extraction framework based on spectral and cepstral parameters is proposed. Using this framework, the phoneme signal is divided into frames and Hamming window is used. The performances are evaluated for recognition of Lithuanian vowel and semivowel phonemes. Different feature sets without noise as well as at different level of noise are considered. Two classical machine learning methods (Naive Bayes and Support Vector Machine) are used for classifying each problem, separately. The experiment results show that cepstral parameters give higher accuracies than spectral parameters. Moreover, cepstral parameters give better performance compared to spectral parameters in noisy conditions.

  • Comparative analysis of thermodynamic cycles of selected nuclear ship power plants with high-temperature helium-cooled nuclear reactor
    • Natalia Szewczuk-Krypa
    • Anna Milewska
    • Jerzy Głuch
    2018 Full text Polish Maritime Research

    This paper presents a comparative analysis of thermodynamic cycles of two ship power plant systems with a high-temperature helium- cooled nuclear reactor. The first of them is a gas system with recuperator , in which classical gas chamber is substituted for a HTGR reactor (High Temperature Gas-cooled Reactor) . The second of the considered cycles is a combined gas-steam system where working medium flux from gas turbine outlet is directed into waste heat boiler and its heat is utilized for production of superheated steam to drive steam turbine. Preliminary calculations of the combine cycles showed that it is necessary to expand the system by adding to its steam part an inter-stage overheat for secondary steam, owing to that a required degree of steam dryness at outlet from the turbine can be reached, ensuring its correct operational conditions. The analyzed power systems were compared to each other with regard to efficiency of their thermodynamic cycles. Also, efficiency of particular cycles were subjected to optimization in respect to such parameters as : working gas temperature at outlet from reactor in gas system as well as steam pressure at outlet from waste heat boiler and partition pressure in steam part of combined system. Advantages of nuclear power plants compared with the classical power systems dominating currently in sea transport were also discussed.

  • Comparative analysis of various transformation techniques for voiceless consonants modeling
    • Grazina Korvel
    • Bożena Kostek
    • Olga Kurasova
    2018 Full text International Journal of Computers Communications & Control

    In this paper, a comparison of various transformation techniques, namely Discrete Fourier Transform (DFT), Discrete Cosine Transform (DCT) and Discrete Walsh Hadamard Transform (DWHT) are performed in the context of their application to voiceless consonant modeling. Speech features based on these transformation techniques are extracted. These features are mean and derivative values of cepstrum coefficients, derived from each transformation. Feature extraction is performed on the speech signal divided into short-time segments. The kNN and Naive Bayes methods are used for phoneme classification. We consider both classfication accuracies and computational time. Experiments show that DFT and DCT give better classification accuracy than DWHT. The result of DFT was not significantly different from DCT, but it was for DWHT. The same tendency was revealed for DCT. It was checked with the usage of the ANOVA test that the difference between results obtained by DCT and DWHT is significant.

  • Comparison analysis of selected nuclear power plants supplied with helium from high-temperature gas-cooled reactor
    • Natalia Szewczuk-Krypa
    • Marta Drosińska-Komor
    • Jerzy Głuch
    • Łukasz Breńkacz
    2018 Full text Polish Maritime Research

    The article presents results of efficiency calculations for two 560 MW nuclear cycles with high-temperature gas-cooled reactor (HTGR). An assumption was made that systems of this type can be used in so-called marine nuclear power plants. The first analysed system is the nuclear steam power plant. For the steam cycle, the efficiency calculations were performed with the code DIAGAR, which is dedicated for analysing this type of systems. The other system is the power plant with gas turbine, in which the combustion chamber has been replaced with the HTGR. For this system, a number of calculations were also performed to assess its efficiency. Moreover, the article names factors in favour of floating nuclear power plants with HTGRs, which, due to passive safety systems, are exposed to much smaller risk of breakdown than other types of reactors which were in common use in the past. Along with safety aspects, it is also economic and social aspect which make the use of this type of systems advisable.

  • Comparison and Optimization of Saccharification Conditions of Alkaline Pre-Treated Triticale Straw for Acid and Enzymatic Hydrolysis Followed by Ethanol Fermentation
    • Rafał Łukajtis
    • Karolina Kucharska
    • Iwona Hołowacz
    • Piotr Rybarczyk
    • Katarzyna Wychodnik
    • Edyta Słupek
    • Paulina Nowak
    • Marian Antoni Kamiński
    2018 Full text ENERGIES

    This paper concerns the comparison of the efficiency of two-stage hydrolysis processes, i.e., alkaline pre-treatment and acid hydrolysis, as well as alkaline pre-treatment followed by enzymatic hydrolysis, carried out in order to obtain reducing sugars from triticale straw. For each of the analyzed systems, the optimization of the processing conditions was carried out with respect to the glucose yield. For the alkaline pre-treatment, an optimal catalyst concentration was selected for constant values of temperature and pre-treatment time. For enzymatic hydrolysis, optimal process time and concentration of the enzyme preparation were determined. For the acidic hydrolysis, performed with 85% phosphoric acid, the optimum temperature and hydrolysis time were determined. In the hydrolysates obtained after the two-stage treatment, the concentration of reducing sugars was determined using HPLC. The obtained hydrolysates were subjected to ethanol fermentation. The concentrations of fermentation inhibitors are given and their effects on the alcoholic fermentation efficiency are discussed.

  • Comparison of antimicrobial activity of selected, commercially available wound dressing materials
    • Piotr Szweda
    • Grzegorz Gorczyca
    • Robert Tylingo
    2018 Journal of Wound Care

    OBJECTIVE: The aim of our study was to examine the antimicrobial potential of eight selected, commercially available wound dressings containing different antimicrobial agents: silver, chlorhexidine acetate, povidone-iodine, and manuka honey. METHOD: The materials were tested against four reference strains of bacteria: Staphylococcus aureus (PCM 2051), Staphylococcus epidermidis (PCM 2118), Pseudomonas aeruginosa (ATCC 27853), and Escherichia coli (K12), using the disc diffusion-like method and a time-killing assay. RESULTS: For both experiments, the highest activity against all four tested strains of bacteria was observed in the case of Mepilex Ag, which contains silver as an antibacterial agent. Incubation for four hours of a 10x10mm2 piece of this material in 10ml cells suspension (concentration: 109-1010CFU/ml) resulted in complete elimination of bacteria of all four strains tested. The same results were obtained for a povidone-iodine containing dressing, Inadine, though its activity was lower in the disc diffusion assay. Silvercel, Aquacel Ag and Melgisorb Ag, which also contain silver, also exhibited a satisfactory level of activity. In the case of Aquacel Ag, 24 hours' incubation resulted in complete elimination of the cells of both Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa.The Escherichia coli cells were killed after only four hours' treatment. High effectiveness against Escherichia coli was also demonstrated for Silvercel. However, 24 hours' includation was required for complete elimination of the cells of this bacteria strain. High activity against all tested bacteria, but only in the disc diffusion assay, was observed for Algivon, which contains manuka honey. The Medisorb Silver Pad, containing silver, and Bactigras, which contains chlorhexidine acetate, revealed much lower antimicrobial activity, particularly noticeable in the time-killing assay. In addition, we also tested the anti-staphylococcal activity of a biopolymer material impregnated with lysostaphin. Results revealed that its activity against Staphylococcus aureus was comparable to the most active wound dressings impregnated with silver or inadine. CONCLUSION: Some important differences in the antimicrobial potential of investigated materials have been found. The presented results could be of interest to clinicians managing wounds.

  • Comparison of Classification Methods for EEG Signals of Real and Imaginary Motion
    • Piotr Szczuko
    • Michał Lech
    • Andrzej Czyżewski
    2018 Full text

    The classification of EEG signals provides an important element of brain-computer interface (BCI) applications, underlying an efficient interaction between a human and a computer application. The BCI applications can be especially useful for people with disabilities. Numerous experiments aim at recognition of motion intent of left or right hand being useful for locked-in-state or paralyzed subjects in controlling computer applications. The chapter presents an experimental study of several methods for real motion and motion intent classification (rest/upper/lower limbs motion, and rest/left/right hand motion). First, our approach to EEG recordings segmentation and feature extraction is presented. Then, 5 classifiers (Naïve Bayes, Decision Trees, Random Forest, Nearest-Neighbors NNge, Rough Set classifier) are trained and tested using examples from an open database. Feature subsets are selected for consecutive classification experiments, reducing the number of required EEG electrodes. Methods comparison and obtained results are presented, and a study of features feeding the classifiers is provided. Differences among participating subjects and accuracies for real and imaginary motion are discussed. It is shown that though classification accuracy varies from person to person, it could exceed 80% for some classifiers.

  • Comparison of Downdraft and Updraft Gasification of Biomass in a Fixed Bed Reactor
    • Jacek Kluska
    • Mateusz Ochnio
    • Paweł Kazimierski
    • Dariusz Kardaś
    2018 Full text Archives of Thermodynamics

    The aim of this study was to compare and analyze the gasification process of beech wood. The experimental investigation was conducted inside a gasifier, which can be operated in downdraft and updraft gasification system. The most important operating parameter studied in this paper was the influence of the amount of supply air on the temperature distribution, biomass consumption and syngas calorific value. The results show that the amount of air significantly influences the temperature in the combustion zone for the downdraft gasification process, where temperature differences reached more than 150 °C. The increased amount of air supplied to the gasifier caused an increase in fuel consumption for both experimental setups. Experimental results regarding equivalence ratio show that for ER below 0.2, the updraft gasification is characterized by a higher calorific value of producer gas, while for ER=0.22 a similar calorific value (6.5 MJ/Nm3) for both gasification configurations was obtained. Above this value, an increase in ER causes a decrease in the calorific value of gas for downdraft and updraft gasifiers.

  • Comparison of edge detection algorithms for electric wire recognition
    • Paweł Kowalski
    • Maciej Czyżak
    • Robert Smyk
    2018

    Edge detection is the preliminary step in image processing for object detection and recognition procedure. It allows to remove useless information and reduce amount of data before further analysis. The paper contains the comparison of edge detection algorithms optimized for detection of horizontal edges. For comparison purposes the algorithms were implemented in the developed application dedicated to detection of electric line wires. The optimized algorithms were benchmarked on a set of images of electric wires.