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Gdańsk University of Technology

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Publications from the year 2017

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  • Modeling of luminance distribution in CAVE-type virtual reality systems
    • Michał Meironke
    • Adam Mazikowski
    2017

    At present, one of the most advanced virtual reality systems are CAVE-type (Cave Automatic Virtual Environment) installations. Such systems are usually consisted of four, five or six projection screens and in case of six screens arranged in form of a cube. Providing the user with a high level of immersion feeling in such systems is largely dependent of optical properties of the system. The modeling of physical phenomena plays nowadays a huge role in the most fields of science and technology. It allows to simulate work of device without a need to make any changes in the physical constructions. In this paper distribution of luminance in CAVE-type virtual reality systems were modelled. Calculations were performed for the model of 6-walled CAVE-type installation, based on Immersive 3D Visualization Laboratory, situated at the Faculty of Electronics, Telecommunications and Informatics at the Gdansk University of Technology. Tests have been carried out for two different scattering distribution of the screen material in order to check how these characteristicinfluence on the luminance distribution of the whole CAVE. The basis assumption and simplification of modeled CAVE-type installation and results were presented. The brief discussion about the results and usefulness of developed model were also carried out.

  • Modeling of performance of an AUV stealth vehicle. Design for operation.
    • Mirosław Gerigk
    2017

    In the paper some results of research connected with modelling of performance and risk assessment of an AUV stealth vehicle are presented. A general approach to design of the stealth AUV autonomous underwater vehicle under consideration is introduced. The basic stealth characteristics of the AUV stealth vehicle are briefly described. The method of research is introduced. The AUV stealth vehicle concept is presented including the hull peculiarities. Between the results of research some basic stealth characteristics of the AUV stealth vehicle are presented. Some final remarks regarding the AUV stelath vehicle performance and its behaviour in the data operational conditions are given. The final conclusions are presented.

  • Modeling of Transient Photocurrent in Organic Semiconductors Incorporating the Annihilation of Excitons on Charge Carriers
    • Damian Głowienka
    • Jędrzej Szmytkowski
    2017 Full text ACTA PHYSICA POLONICA A

    The role of the annihilation of excitons on charge carriers has been theoretically investigated in organic semiconductors. We have developed the numerical drift-diffusion model by incorporation terms which describe the annihilation process. The transient photocurrent has been calculated for different injection barrier heights, exciton mobilities, and annihilation rate constants. We have demonstrated that the annihilation has a great influence on the range and the rising time of the photocurrent.

  • Modeling the Customer’s Contextual Expectations Based on Latent Semantic Analysis Algorithms
    • Nina Rizun
    • Katarzyna Ossowska
    • Jurij Taranenko
    2017 Full text

    Nowadays, in the age of Internet, access to open data detects the huge possibilities for information retrieval. More and more often we hear about the concept of open data which is unrestricted access, in addition to reuse and analysis by external institutions, organizations and people. It’s such information that can be freely processed, add another data (so-called remix) and then published. More and more data are available in text format (such as reviews on books, movies, etc.). Algorithms of Latent Semantic Relations Analysis are one of the important tools for extraction and recognition of significant facts from textual data sets. Another aspect of research is to find ways and means of using the information obtained by Semantic tools applying in order to maximize the expected benefit. In this area, one of the modern tools for formulating the concept of benefits is the Benefits Language [1–5]. One of the conditions for the formation of the concept of benefits for studied product is the collection and processing © Springer International Publishing AG 2018 J. Świątek et al. (eds.), Information Systems Architecture and Technology: Proceedings of 38th International Conference on Information Systems Architecture and Technology – ISAT 2017, Advances in Intelligent Systems and Computing 656, DOI 10.1007/978-3-319-67229-8_33 of information about the client’s expectations. This process often requires additional time and financial costs. Therefore, one of the ways to obtain the “maximum benefit” of using the Benefits language is to develop a methodology of building the system of customer’s contextual expectations via systematic usage of benefit’s theory and algorithms of semantic analysis of textual opinions of open Internet pages’.

  • Modeling the impact of discretizing rotor angular position on computation of field-oriented current components in high speed electric drives
    • Leszek Jarzębowicz
    2017 Full text APPLIED MATHEMATICAL MODELLING

    Modern drives consist of alternating current electric motors, and the field-oriented control (FOC) of such motors enables fast, precise, and robust regulation of a drive's mechanical variables such as torque, speed, and position. The control algorithm, implemented in a microprocessor, requires feedback from motor currents, and the quality of this feedback is essential to a drive's control properties. Motor phase currents are sampled and processed in order to extract their mean over a digital control interval. Afterwards, the mean phase currents are transformed into a rotating field-oriented reference frame to enable controlling the mechanical variables. The field-oriented frame rotates continuously, but in practice the transformation is carried out using a discrete angular position. This paper investigates how the discretization impacts the computed field-oriented currents in high speed drives, where the rotor displacement during a control interval is substantial. A continuous-time model of field-oriented currents is indicated as a reference to quantify errors. An original approach to normalize variables and to solve the model analytically is proposed in order to investigate how the errors related to rotor position discretization are influenced by drive operating conditions. The analytical solution is validated by computer simulation. The results show that the currently applied methodology of computing field-oriented current components, due to an invalid assumption, introduces errors of a few percent when a drive operates at high speed. These errors can be compensated using the presented solution.

  • Modeling the impact of rotor movement on non-linearity of motor currents waveforms in high-speed PMSM drives
    • Leszek Jarzębowicz
    • Slobodan Mirchevski
    2017 Full text

    Motor current measurement techniques as well as predictive control algorithms for electric drives rely on an assumption of linear motor currents changes resulting from constant inverter output voltages. Recent research has reported that this assumption does not hold in motors with short electrical time constant, and in drives whose rotor position advances substantially during a control period. This paper proposes a simulation model that reflects the non-linearity of currents waveforms. The hybrid model, designed in Matlab/Simulink, consists of both continuous- and discrete-time subsystems. Operation of the inverter can be reproduced in either a simplified manner — by reflecting only the fundamental voltage component, or in detail — by modeling the pulse-width-modulated motor voltages. The proposed model is validated with respect to reproducing the non-linearity of currents waveforms by comparison with a laboratory high-speed PMSM drive.

  • Modeling the pH effects on nitrogen removal in the anammox-enriched granular sludge
    • X. Lu
    • Z. Yin
    • Dominika Sobotka
    • Kamil Wiśniewski
    • Krzysztof Czerwionka
    • L. Xie
    • Q. Zhou
    • Jacek Mąkinia
    2017 WATER SCIENCE AND TECHNOLOGY

    The aim of the study was to determine the pH effects on nitrogen removal in the anammox-enriched granular sludge. The experimental data were extracted from a 4L completely-mixed batch reactor with the granular sludge at different initial pH values (6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5) and constant temperature T=30℃. Simulations were run in GPS-X 6.4 using a comprehensive mechanistic model Mantis2. Two kinetic parameters, including the maximum specific growth rates of ammonia oxidizing bacteria (AOB) and anammox bacteria were optimized at different pH scenarios. The inhibitory effects of the pH extremes on the anammox-enriched sludge were discussed in terms of the inhibition of free nitrous acid (FNA) and free ammonia (FA) and metabolic mechanisms. Two different pH functions were used to examine the pH effects on the nitrogen removal kinetics. The pH optima for AOB and anammox bacteria were 7.4 and 7.6, respectively. The maximum specific growth rates of AOB and anammox bacteria at the pH optima were 0.84 d-1 and 0.37 d-1 (at T=30℃). The measured specific anammox activities (SAAs), predicted SAAs by Mantis2 and fitted SAAs by the Michaelis pH function at the pH optima were 0.895 gN/(gVSS·d), 0.829 gN/(gVSS·d) and 0.831 gN/(gVSS·d), respectively.

  • Modeling variable curvature on the turnout diverging track length
    • Władysław Koc
    2017 Full text Przegląd Komunikacyjny

    The paper presents three variants of variable curvature application on the entire length of the turnout diverging track. One linear and two nonlinear curvature cases: described the function of C1 and C0 class were considered. It turned out that both linear curve and the function of C1 class requires a significant (even twice) length of diverging track extending with respect to the base turnout. The curvature described by the function of class C0 proved to be far more favorable, although the necessary extension of the turnout is still considerable. In the turnouts with variable curvature of diverging track it is possible to shape the horizontal ordinates flexibly by manipulating the crossing angle and radius. The study shows the effects of such a procedure, the aim of which was to obtain an appropriate value of the final ordinate.

  • Modelling and Simulation of a New Variable Stiffness Holder for Milling of Flexible Details
    • Krzysztof Jan Kaliński
    • Marek Galewski
    • Michał Mazur
    • Marek Chodnicki
    2017 Full text Polish Maritime Research

    Modern industry expectations in terms of milling operations often demand the milling of the flexible details by using slender ball-end tools. This is a difficult task because of possible vibration occurrence. Due to existence of certain conditions (small depths of cutting, regeneration phenomena), cutting process may become unstable and self-excited chatter vibration may appear. Frequency of the chatter vibration is close to dominant natural frequency of the workpiece or the tool. One of the methods of chatter vibration avoidance is matching the spindle speed to the optimum phase shift between subsequent cutting edges passes (i.e. the Liao-Young condition). However, the set of optimum spindle speeds from the point of view of vibration reduction may be not optimum one from other points of view. For example milling efficiency or machine tool capabilities cannot be assured. This article presents the idea of a workpiece holder with adjustable stiffness and discusses a new variant of its realization. In the holder , milling process is performed at constant spindle speed and feed speed. In order to avoid vibration the holder stiffness is modified. Stiffness changes modify natural frequencies of the workpiece and thus it is possible to modify dynamic properties of the workpiece in such a way that arbitrary chosen, constant spindle speed will be optimum, due to the Liao-Young condition performance. Calculation of the optimum stiffness is performed before milling, based on the workpieces modal identification results and the finite element model simulations.

  • Modelling charge transfer processes in C2+ -tetrahydrofuran collision for ion-induced radiation damage in DNA building blocks
    • Ewa Erdmann
    • Marie Christine Bacchus-Montabonel
    • Marta Łabuda
    2017 Full text PHYSICAL CHEMISTRY CHEMICAL PHYSICS

    Investigations of collision-induced processes involving carbon ions and molecules of biological interest in particular DNA building blocks, are crucial to model the effect of radiation on cells in order to improve medical treatments for cancer therapy. Using carbon ions appears to be one of the most efficient ways to increase biological effectiveness to damage cancerous cells by irradiating deep-seated tumors. Therefore, interest in accurate calculations to understand fundamental processes occurring in ion–molecule collision systems has been growing recently. In this context, the charge transfer process in the collision of C2+(1s22s2) ions with the heterocyclic sugar moiety building block tetrahydrofuran (THF) was studied in order to interpret the mechanisms occurring at the molecular level. The molecular structure properties of THF were obtained by means of ab initio quantum chemistry methods. The role of the conformational structure and the orientation of the THF molecule in collision with C2+ ions are particularly discussed. Anisotropic effects of the process dynamics in the collision energy ranging from eV to keV by means of semiclassical treatment are also presented and compared to previous experimental and theoretical investigations. A detailed analysis of the obtained cross sections points out an increase in these values by three orders of magnitude by a change of the THF symmetry from C2v to Cs in collision with C2+, which determines a more efficient charge transfer in this case.

  • Modelling fatalities on regional road networks
    • Joanna Wachnicka
    2017 Full text MATEC Web of Conferences

    During the last decade Poland’s road fatalities went down by 44%. The trend differs from region to region. Effective road safetymanagement in regions requires tools for forecasting road safety measures and identifying factors influencing road fatality numbers. Mathematical models can provide such tools. They take into account local characteristics such as: demography, economy, infrastructure and motorization. Such models could be used for better regional road safety management. This paper presents an attempt to build such models used for forecasting road fatalities in EU regions and Polish voivodships.

  • Modelling of high frequency dynamic responses of engineering structures
    • Arkadiusz Żak
    • Marek Krawczuk
    • Grzegorz Redlarski
    • Wiktor Waszkowiak
    2017

    Modelling of high frequency dynamic responses of engineering structures, especially those related to wave propagation, is a real numerical challenge. Nowadays most of numerical models, used for that purpose, are based on the application of various finite element techniques. However, finite element discrete models may also be considered as possessing certain periodic structures, which may manifest themselves in particular scenarios. The source of their periodicity comes from the discontinuity of the stress/strain field between adjacent finite elements, which usually are ignored by modellers as having no influence on numerical results. Indeed, their influence remains unnoticeable, when low frequency dynamics is investigated. On the other hand at high frequency regimes its influence may be strong enough to dominate calculated structural dynamic responses distorting or even falsifying them completely. In this paper certain issues of modelling of high frequency dynamic responses by finite element techniques are discussed by the authors. In this discussion the authors focus their interest on exemplary problems related to modal analysis as well as wave propagation, with a special attention paid to the periodicity of numerical finite element models. The authors also present and discuss certain methods to minimise, or avoid, the numerical issues mentioned.

  • Modelling of Mechanical Behaviour of High-Frequency Piezoelectric Actuators Using Bouc-Wen Model
    • Rafał Kędra
    • Magdalena Rucka
    2017 Full text Metrology and Measurement Systems

    The paper presents the application of a modified, symmetrical Bouc-Wen model to simulate a mechanical behaviour of high-frequency piezoelectric actuators (PAs). In order to identify parameters of the model, a two-step algorithm was utilized. In the first stage, the mechanical parameters were identified by taking into account their bilinear variability and using a square input voltage waveform. In the second step, the hysteresis parameters were determined based on a periodic excitation. Additionally, in order to reduce the influence of measurement errors in determination of selected derivatives the continuum wavelet transform (CWT) and translation-rotation transformation (TRT) methods were applied. The results confirmed that the modified symmetrical Bouc-Wen model is able to describe the mechanical behaviour of PAs across the wide frequency range.

  • Modelling of shear localization during granular flow within non-local hypoplasticity using material point method
    • Paweł Hajko
    • Andrzej Tejchman-Konarzewski
    2017 SpringerPlus

    Artykuł omawia wyniki numeryczne dotyczące powstawania lokalizacji odkształceń stycznych w materiałach granulowanych Obliczenia wykonano dla ściskania dwuosiowego i przypływu silosowego stosując hipoplastyczny model konstytutywny rozszerzony o długość charakterystyczną w ramach nielokalnej teorii. Zastosowano podejście punktów materialnych w celu uniknięcia nadmiernej deformacji elementów skończonych.

  • Modelling of steady state and transient performance of the synchronous generator considering harmonic distortions caused by non-uniform saturation of the pole shoe
    • Filip Kutt
    • Michał Michna
    • Grzegorz Andrzej Kostro
    • Mieczysław Ronkowski
    2017 ELECTRIC POWER SYSTEMS RESEARCH

    In this paper a synchronous generator model is described. This model is developed on the assumption that in loaded and no load conditions the saturation effect affects the pole shoe in a different way. The developed model is based on the multiple saliency model and is formulated using winding function approach in machine variables. The influence of the non-uniform saturation of the pole shoe in load conditions on the performance of the generator is investigated. Simulation results of the model are compared with the measurements on selected salient pole synchronous generator for steady and transient states.

  • Modelling of subarachnoid space width changes in apnoea resulting as a function of blood flow parameters
    • Renata Kalicka
    • Kamila Mazur
    • Jacek Wolf
    • Andrzej F. Frydrychowski
    • Krzysztof Narkiewicz
    • Krzysztof Narkiewicz
    • Paweł J. Winklewski
    2017 MICROVASCULAR RESEARCH

    During apnoea, the pial artery is subjected to two opposite physiological processes: vasoconstriction due to elevated blood pressure and vasorelaxation driven by rising pH in the brain parenchyma. We hypothesized that the pial artery response to apnoea may vary, depending on which process dominate. Apnoea experiments were performed in a group of 19 healthy, non-smoking volunteers (9 men and 10 women). The following parameters were obtained for further analysis: blood pressure, the cardiac (from 0.5 to 5.0 Hz) and slow (< 0.5 Hz) components of subarachnoid space width, heart rate, mean cerebral blood flow velocity in the internal carotid artery, pulsatility and resistivity index, internal carotid artery diameter, blood oxygen saturation and end-tidal carbon dioxide. The experiment consisted of three apnoeas, sequentially: 30s, 60s and maximal apnoea. The breath-hold was separated for 5 minute rest. The control process is sophisticated, involving internal cross-couplings and cross-dependences. The aim of work was to find a mathematical dependence between data. Unexpectedly, the modelling revealed two different reactions, on the same experimental procedure. As a consequence, there are two subsets of cardiac subarachnoid space width responses to breath-hold in humans. A positive cardiac subarachnoid space width change to apnoea depends on changes in heart rate and cerebral blood flow velocity. A negative cardiac subarachnoid space width change to apnoea is driven by heart rate, mean arterial pressure and pulsatility index changes. The described above two different reactions to experimental breath-hold provides new insights into our understanding of the complex mechanisms governing the adaptation to apnoea in humans. We proposed a mathematical methodology that can be used in further clinical research.

  • Modelling of the Polish Electricity Generation Subsystem in MARKAL Program with Emphasis on the EU Emissions Trading Scheme
    • Magdalena Malinowska
    • Marcin Jaskólski
    2017 Full text Acta Energetica

    This paper addresses issues related to greenhouse gas emissions in the European Union and measures to reduce them, in particular the European Emissions Trading Scheme (EU ETS). A model of the Polish electricity generation subsystem, taking into account EU ETS mechanisms, has been developed using the MARKAL optimization package. Data collected on the basis of available projects, regulations and statistics were entered into the model. The results of the modelling were used for formulating the following conclusions. Even the very high price of emission allowances (103 EUR/t CO2-eq) will not result in complete decarbonisation of the power sector by 2030. However, the allowance price levels will have a significant impact on the structure of electricity generation and the electrical power available in the system. Only high allowance prices will be an incentive to invest in renewable and nuclear energy based generation units. Power generation technologies with CO2 capture systems can be a chance to sustain the carbon economy while reducing emissions, but the problem will be the large-scale carbon dioxide storage.

  • Modelling, Simulation and Optimization of the Wavemaker in a Towing Tank
    • Marcin Drzewiecki
    2017 Advances in Intelligent Systems and Computing

    The paper analyses the problem of experimental identification (frequency response), modelling and optimization of the towing tank wavemaker in the Scilab/Xcos environment. The experimental identification of the objects (the towing tank wavemaker placed in the hydrodynamic laboratory of the CTO S.A. Ship Design and Research Centre (CTO)) and the implementation of the models in the simulation environment, enable to perform: 1. tuning of the cascade PID controller (Astrom-Hagglund relay method), 2. checking the stability (Routh-Hurvitz criterion, Nyquist criterion) of the wavemaker with tuned controller, 3. evaluating the regulatory quality and simulating of work of the optimized (Ziegler-Nichols method) system of the wavemaker. The above works and the achieved results are further described and presented in the content of this paper.

  • Modelowanie analogowe w analizie jakościowej rozchodzenia się drgań
    • Eligiusz Mieloszyk
    • Sławomir Grulkowski
    2017 Full text Przegląd Komunikacyjny

    Proces rozprzestrzeniania się drgań zachowuje się analogicznie jak inne znane zjawiska podobne do niego, np. zjawisko drgań układów elektrycznych, mechanicznych, hydraulicznych, zjawisko dyfuzji, zjawisko rozchodzenia się ciepła, zjawisko falowe, czy zjawisko adwekcji. Do analizy problemu zostaną wykorzystane zjawiska podobne i uogólnione układy dynamiczne. Da to możliwość wyciągania wniosków co do zachowania się jednego procesu na podstawie innego, podobnego do niego. Taka koncepcja zostanie wykorzystana przy analizie jakościowej rozchodzenia się drgań, w szczególności w gruncie, czy podłożu gruntowym inżynierskich obiektów transportowych.

  • Modelowanie cech hydromechanicznych dwustanowych bezzałogowych obiektów pływających.
    • Mirosław Gerigk
    2017

    W artykule przedstawiono ogólny zarys problematyki związanej z badaniami i projektowaniem dwustanowych bezzałogowych obiektów pływających. Na początku, przedstawiono badania interdyscyplinarne i możliwości wdrożenia efektów badań. następnie scharakteryzowano tak zwane technologie zaawansowane zastosowanie, których jest niezbędne podczas badań i w czasie projektowania dwustanowych bezzałogowych obiektów pływających. Omówiono metodę badań własnych. Z kolei opisano dwustanowy pojazd podwodny typu AUV-Stealth. Główna część artykułu została poświęcona omówieniu problemów związanych z modelowaniem cech hydromechanicznych dwustanowych bezzałogowych obiektów pływających, w tym: pływalność i stateczność pojazdu, ruch i mobilność pojazdu, trudnowykrywalność pojazdu. W końcowej części artykułu przedstawiono wyzwania związane z dalszym rozwojem obiektów wielostanowych. Podano wnioski końcowe.