2018 - Repozytorium publikacji - Politechnika Gdańska

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Publikacje z roku 2018

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Longitudinal Motion Due to Action of Tunnel Thrusters
- Maciej Reichel
2018 Pełny tekst Polish Maritime Research
Tunnel thrusters are propulsion and active control devises that provide a side force, or transverse thrust, to support mooring operations or position keeping. They shorten the time of manoeuvring, reduce the cost of towage and since inception, manoeuvrability specifically in ports has become a lot easier. Tunnel thrusters can either be operated manually or with the help of Dynamic Positioning systems which makes it even more efficient. Theoretically, the transverse force due to tunnel thruster action should generate only lateral and rotational motion. Therefore, it is typical and a common practice during manoeuvring simulations that the longitudinal motion due to the action of tunnel thrusters is neglected. Nevertheless, the experience of masters and pilots shows that some longitudinal motion due to the action of tunnel thrusters appears. This paper shows some examples of turning manoeuvres carried out with bow thrusters only, i.e. no additional control devices or tug assistance have been used. The manoeuvres have been carried with minimal possible initial longitudinal nor lateral speed. Model tests have been done with the use of large manned models of VLCS, PCTC and LNG carrier, which differ in hull shape, dimensions and shape coefficients. Results obtained from the tests confirm that the motion caused by bow thruster besides rotational and lateral motion consists additionally of longitudinal motion. Analysis of the combination of motions due to the action of tunnel thrusters have been done and some rationale for this phenomenon has been presented. Additionally a short analysis of position of pivot point during tunnel thruster test has been carried out.
Long-term operation of Kickuth-type constructed wetland applied to municipal wastewater treatment in temperate climate
- Zbigniew Mucha
- Włodzimierz Wójcik
- Krzysztof Jóźwiakowski
- Magdalena Gajewska
2018 Pełny tekst ENVIRONMENTAL TECHNOLOGY
The purpose of this paper is to discuss the problem of changes of effectiveness of Kickuth-type constructed wetland with subsurface flow applied to domestic wastewater treatment. This study is based on an example of a wetland 3000 m2 in surface, serving 800 inhabitants, located in Poland. The results of chemical analysis showed that after an initial year of ‘start-up time’, the efficiency of pollutant removal gradually increased to reach an apex in the 6th year of operation. Such maximum efficiency continued up to the 10th year of operation; afterwards it gradually dropped. Moreover, after 12 years of operation, a serious problem with overland flow was observed, which indicated the porous media clogging processes.
Low cost real time UAV stereo photogrammetry modelling technique – accuracy considerations
- Paweł Burdziakowski
2018 Pełny tekst E3S Web of Conferences
The paper presents accuracy considerations regarding three 3D modelling techniques. The tested new consumer type stereo camera (ZED 3D Stereolabs) has been implemented info an aerial mapping system, on board micro air vehicle MAV) and tested object has been mapped using a real-time photogrammetry with original real-time software application. The evaluated results has been compared with model gained with a state of art unmanned aerial vehicles (UAV) photogrammetry process using commercial UAV and commercial software, and the terrestrial photogrammetry modelling process with other commercial software. Papers concludes the tested real-time technology accuracy with compare to the traditional technique, and discusses real-time photogrammetry modelling in terms of engineering applications.
Low cost set-up for supercapacitors parameters evaluation
- Arkadiusz Szewczyk
2018
We propose a use of a power amplifier in the circuit of voltage to current converter (current driver) for supercapacitor charging/discharging in controlled conditions. The current driver is controlled by DAC output of DAQ board and voltage of DUT is measured and a control loop is realized by software. In the circuit the DC current method of evaluation of capacitance and equivalent series resistance is used. The DUT is charged and discharged with constant current and capacitance C and equivalent serial resistance ESR are calculated from voltage curves. For test purpose commercially available supercapacitors were measured with different current values. The designed test circuit is a low-cost alternative for professional and semi-professional systems. It gives several advantages as easy control of charging current and possibility of applying various current patterns.
Low cost set-up for supercapacitors parameters evaluation
- Arkadiusz Szewczyk
2018 Pełny tekst Journal of Physics : Conference Series
Supercapacitors are capable to store relatively high amount of energy comparing to its mass. Growing number of these devices applications requires development of new testing methods. Standard methods of evaluation of supercapacitor parameters, as cycling voltammetry, CV, galvanostatic cycling with potential limitation, GCPL, impedance measurements, require equipment of high cost as potentiostat/galvanostat with high current efficiency. We propose a use of a ower amplifier in the circuit of voltage to current converter (current driver) for supercapacitor charging/discharging in controlled onditions. The current driver is controlled by DAC output of DAQ board and voltage of DUT is measured and a control oop s realized by software. In the circuit the DC current method of evaluation of capacitance and equivalent series resistance is sed. The DUT is charged and discharged with constant current and capacitance C and equivalent serial resistance ESR are alculated from voltage curves. For test purpose commercially available supercapacitors were measured with different current alues. The designed test circuit is a low-cost alternative for professional and semi-professional systems. It gives several advantages as easy control of charging current and possibility of applying various current patterns.
Low energy differential elastic electron scattering from acetonitrile (CH3CN)
- Mateusz Zawadzki
- Murtadha Khakoo
2018 Pełny tekst JOURNAL OF CHEMICAL PHYSICS
Measurements of elastic differential cross sections for electron scattering from acetonitrile (CH3CN) have been performed utilizing a crossed electron-molecular beam experiment and with the relative flow method, for the incident electron energy range of 0.7 eV–30 eV and the scattering angle range of 10◦–130◦. These differential cross sections have been used to calculate the elastic integral and momentum- transfer cross sections, revealing a π* resonance located around 3 eV. The elastic differential cross sections are compared with available theoretical models using the R-matrix method and the Schwinger multichannel method.
Low temperature deposition of dense MnCo 2 O 4 protective coatings for steel interconnects of solid oxide cells
- Bartosz Kamecki
- Jakub Karczewski
- Tadeusz Miruszewski
- Grzegorz Jasiński
- Dagmara Szymczewska
- Piotr Jasiński
- Sebastian Molin
2018 Pełny tekst JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
In this work manganese cobalt spinel (MnCo2O4) coatings were deposited on steel substrates by spray pyrolysis at 390 °C. This is at much lower temperatures than previously reported (typically in excess of 900 °C). It was possible to produce coatings with well controlled thickness (2-5-10 μm). The as-deposited coatings were evaluated for their microstructural changes and electrical conductivity up to 800 °C. Results confirm the formation of a single phase spinel with high density and electrical conductivity. Based on the obtained results, it might be concluded that spray pyrolysis is a very promising method to develop protective coatings for steel substrates at low temperatures overcoming limitations of many other methods.
Low-Coherence Interferometer with Nanocrystalline Diamond Films with Potential Application to Measure Small Biological Samples
- Marzena Hirsch
- Monika Kosowska
- Daria Majchrowicz
- Przemysław Struk
- Paweł Wierzba
- Mateusz Ficek
- Kamatchi J Sankaran
- Ken Haenen
- Małgorzata Szczerska
2018 PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
The study investigates a case of a low-coherence fiber-optic Fabry–Prerot interferometer with a nanocrystalline diamond (NCD) mirror. The method of achieving double density of interference fringes is proposed by the application of birefringent material in the cavity of the interferometer. It can be used to reduce sample volume in comparison to conventional interferometers. The use of a biocompatible diamond mirror makes it specifically well suited for application in biosensing. The fabrication process and surface characterization of the nitrogen-doped NCD and boron-doped NCD films are described. The results of numerical modeling and experimental measurements are discussed.
Low-cost and reliable geometry scaling of compact microstrip couplers with respect to operating frequency, power split ratio, and dielectric substrate parameters
- Sławomir Kozieł
- Adrian Bekasiewicz
2018 IET Microwaves Antennas & Propagation
A technique for rapid re-design of miniaturised microstrip couplers with respect to operating conditions as well as material parameters of the dielectric substrate is proposed. The dimension scaling process is based on a set of pre-optimised reference designs, obtained for an equivalent circuit model of the coupler at hand. The reference designs are utilised to construct an inverse surrogate model which – upon suitable correction – yields the optimum geometry parameter values of the structure re-designed for required values of operating conditions and substrate parameters. An iterative fine-tuning process necessary to account for the surrogate model inaccuracies is also developed. The proposed methodology is validated using a compact rat-race coupler example. The obtained results demonstrate that accurate scaling is possible at a low cost of up to three EM simulations of the structure. For a considered example, the scaling is realised within a wide range of operating conditions (1–2 GHz for the operating frequency, −3 to 0 dB for power split) and substrate parameters (0.7–1.5 mm for the thickness, and 2.5–3.5 for dielectric permittivity). Numerical results are validated experimentally.
Low-Cost Flight Simulator with Possibility of Modeling of Flight Controls Failures
- Piotr Moczulski
- Mariusz Domżalski
2018 Advances in Intelligent Systems and Computing
The goal of this paper is to present a development of a low cost flight simulator, that allows to simulate flight controls failures. Cessna 172 has been chosen as an example of a general aviation aircraft and the flight model has been implemented in Simulink. The model allows for easy integration of an experimental autopilot, using various strategies. Aerodynamic coefficients have been calculated using software called DATCOM. Such approach reduces greatly the cost of development. An approximate inertia matrix has been calculated for proper rigid body dynamics, and a model of engine and propeller is based on actual data from producer. In the end evaluation has been performed, indicating that modeled airplane behaves in a proper way.
Low-cost multiband compact branch-line coupler design using response features and automated EM model fidelity adjustment
- Sławomir Kozieł
- Adrian Bekasiewicz
2018 Pełny tekst INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING
Design closure of compact microwave components is a challenging problem because of significant electromagnetic (EM) cross-couplings in densely arranged layouts. A separate issue is a large number of designable parameters resulting from replacement of conventional transmission line sections by compact microstrip resonant cells. This increases complexity of the design optimization problem and requires employment of expensive high-fidelity EM analysis for reliable performance evaluation of the structure at hand. Consequently, neither conventional numerical optimization algorithms nor interactive approaches (e.g., experience-driven parameters sweeps) are capable of identifying optimum designs in reasonable timeframes. Here, we discuss application of feature-based optimization for fast design optimization of dual- and multiband compact couplers. On one hand, design of such components is difficult because of multiple objectives (achieving equal power split and good matching and port isolation for all frequency bands of interest). On the other hand, because of well-defined shapes of the S-parameter responses for this class of components, feature-based optimization seems to be well suited to control multiple figures of interest as demonstrated in this work. Two-level EM modeling is used for further design cost reduction. More importantly, we develop a procedure for automated determination of the low-fidelity EM model coarseness that allows us to find the fastest possible model that still ensures sufficient correlation with its high-fidelity counterpart, which is critical for robustness of the optimization process. Our approach is illustrated using two dual-band compact couplers. Experimental validation is also provided.
Low-Cost Multi-Objective Optimization of Antennas By Means Of Generalized Pareto Ranking Bisection Algorithm
- S Unnsteinsson
- Sławomir Kozieł
2018
This paper introduces a generalized Pareto ranking bisection algorithm for low-cost multi-objective design optimization of antenna structures. The algorithm allows for identifying a set of Pareto optimal sets of parameters (that represent the best trade-offs between considered objectives) by iterative partitioning of the intervals connecting previously found designs and executing a Pareto-ranking-based poll search. The initial approximation of the Pareto front found using the bisection procedure is subsequently refined to the level of the high-fidelity EM model of the antenna at hand using local optimization. A serious limitation of the original bisection algorithm was that only two objectives could be considered. The generalized version proposed here allows for handling any number of design goals. An improved poll search procedure has also been developed and incorporated. Our algorithm has been demonstrated using an example of a UWB monopole antenna with three figures of interest taken into account: structure size, reflection response, and gain variability.
Low-energy electron scattering from molecular hydrogen: Excitation of the X1Σg+ to b3Σu+ transition
- Mateusz Zawadzki
- Robert Wright
- Grant Dolmat
- Merl Martin
- B Diaz
- Leigh Hargreaves
- D Coleman
- Dmitry Fursa
- Mark Zammit
- Liam Scarlett
- Jonathan Tapley
- Jeremy Savage
- Igor Bray
- Murtadha Khakoo
2018 Pełny tekst PHYSICAL REVIEW A
We present time-of-flight differential cross-section measurements and convergent close-coupling calculations of differential cross sections for the electron-impact excitation of the X 1 g + → b 3 u + transition in molecular hydrogen. A part of this work was recently published [M. Zawadzki et al., Phys. Rev. A 97, 050702(R) (2018)]. In this work, agreement between theory and experiment is excellent overall, and marks a transition in electron-molecule scattering where differential scattering of excitation is found to be in such precise agreement. We also present total electron-impact excitation differential cross sections for H2 for which agreement between theory and experiment is found to be excellent.
Low-fidelity model considerations for simulation-based optimisation of miniaturised wideband antennas
- Sławomir Kozieł
- Sigmar Unnsteinsson
- Adrian Bekasiewicz
2018 IET Microwaves Antennas & Propagation
Here, variable-fidelity electromagnetic (EM)-based design optimisation of miniaturised antennas is discussed. The authors focus on an appropriate selection of discretisation density of the low-fidelity EM model, which results in good performance of the optimisation algorithm in terms of its computational complexity and reliability. Trust-region gradient search with low-fidelity model corrected by means of non-linear frequency scaling and multiplicative output space mapping is utilised as a benchmark optimiser. Comprehensive studies are conducted for several structures of planar wideband antennas, optimised for best matching and minimum size. The results indicate that appropriate low-fidelity model set-up can be determined by means of a correlation analysis based on selected characteristic points of the antenna responses and sparsely allocated test designs.
Ludzkość-technologia: organizm symbiotyczny
- Jarosław Wawer
2018 Elektronika dla wszystkich
Felieton popularnonaukowy dotyczący filozofii techniki.
Łączenie danych pomiarowych z dodatkową wiedzą metrologiczną w celu oceny niepewności pomiaru
- Wojciech Toczek
- Bala Sasi Rekha Nagothu
2018 Pełny tekst Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
Przedstawiono modus operandi w ocenie niepewności pomiaru dla krótkich serii pomiarowych. Metoda wykorzystuje dodatkową wiedzę metrologiczną do zwiększenia liczby stopni swobody rozkładu t-Studenta, uzyskiwanego w wyniku bayesowskiej analizy wyników pomiarów. W rezultacie możliwe jest oszacowanie niepewności standardowych dla najkrótszych serii pomiarowych, o długości n=2 i n=3.
Machine Learning Algorithm-Based Tool and Digital Framework for Substituting Daylight Simulations In Early- Stage Architectural Design Evaluation
- Kacper Radziszewski
- Marta Waczyńska
2018
The aim of this paper is to examine the new method of obtaining the simulation-based results using backpropagation of errors artificial neural networks. The primary motivation to conduct the research was to determine an alternative, more efficient and less timeconsuming method which would serve to achieve the results of daylight simulations. Three daylight metrics: Daylight Factor, Daylight Autonomy and Daylight Glare Probability have been used to verify the reliability of applying the latter into an early stage architectural design process. The framework was based on the computationally generated data sets build on various office models variants followed by daylight simulations. In order to predict the simulations values based on the given office parameters with artificial neural networks algorithm, a specific tool was designed as an alternative to computer simulations. The designed tool and simulations results were compared against computing time and values differences. The above findings of the research proof the reliability of the new methods as a tool during an early-stage architectural design process likewise conventional daylight simulations.
Machine Learning Applied to Aspirated and Non-Aspirated Allophone Classification—An Approach Based on Audio "Fingerprinting"
- Magdalena Piotrowska
- Grazina Korvel
- Adam Kurowski
- Bożena Kostek
- Andrzej Czyżewski
2018
The purpose of this study is to involve both Convolutional Neural Networks and a typical learning algorithm in the allophone classification process. A list of words including aspirated and non-aspirated allophones pronounced by native and non-native English speakers is recorded and then edited and analyzed. Allophones extracted from English speakers’ recordings are presented in the form of two-dimensional spectrogram images and used as input to train the Convolutional Neural Networks. Various settings of the spectral representation are analyzed to determine adequate option for the allophone classification. Then, testing is performed on the basis of non-native speakers’ utterances. The same approach is repeated employing learning algorithm but based on feature vectors. The achieved classification results are promising as high accuracy is observed.
Machine Learning in Multi-Agent Systems using Associative Arrays
- Przemysław Spychalski
- Ryszard Arendt
2018 Pełny tekst PARALLEL COMPUTING
In this paper, a new machine learning algorithm for multi-agent systems is introduced. The algorithm is based on associative arrays, thus it becomes less complex and more efficient substitute of artificial neural networks and Bayesian networks, which is confirmed by performance measurements. Implementation of machine learning algorithm in multi-agent system for aided design of selected control systems allowed to improve the performance by reducing time of processing requests, that were previously acknowledged and stored in learning module. This article contains an insight into different machine learning algorithms and includes the classification of learning techniques regarding the criteria depicted by multi-agent systems. The publication is also an attempt to provide the answer for a question posted by Shoham, Powers and Grenager: “If multi-agent learning is the answer, what is the question?”
MACHINE VISION DETECTION OF THE CIRCULAR SAW VIBRATIONS
- Jakub Sandak
- Kazimierz Orłowski
2018 Pełny tekst Journal of Machine Engineering
Dynamical properties of rotating circular saw blades are crucial for both production quality and personnel safety. This paper presents a novel method for monitoring circular saw vibrations and deviations. A machine vision system uses a camera and a laser line projected on the saw’s surface to estimate vibration range. Changes of the dynamic behaviour of the saw were measured as a function of the rotational speed. The critical rotational speed of the circular saw blade as well as the optimal rotational speed of the saw were detected.