2019 - Publications Repository - Gdańsk University of Technology

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Publications from the year 2019

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Selected Technical Issues of Deep Neural Networks for Image Classification Purposes
- Michał Grochowski
- Arkadiusz Kwasigroch
- Agnieszka Mikołajczyk
2019 Full text Bulletin of the Polish Academy of Sciences-Technical Sciences
In recent years, deep learning and especially Deep Neural Networks (DNN) have obtained amazing performance on a variety of problems, in particular in classification or pattern recognition. Among many kinds of DNNs, the Convolutional Neural Networks (CNN) are most commonly used. However, due to their complexity, there are many problems related but not limited to optimizing network parameters, avoiding overfitting and ensuring good generalization abilities. Therefore, a number of methods have been proposed by the researchers to deal with these problems. In this paper, we present the results of applying different, recently developed methods to improve deep neural network training and operating. We decided to focus on the most popular CNN structures, namely on VGG based neural networks: VGG16, VGG11 and proposed by us VGG8. The tests were conducted on a real and very important problem of skin cancer detection. A publicly available dataset of skin lesions was used as a benchmark. We analyzed the influence of applying: dropout, batch normalization, model ensembling, and transfer learning. Moreover, the influence of the type of activation function was checked. In order to increase the objectivity of the results, each of the tested models was trained 6 times and their results were averaged. In addition, in order to mitigate the impact of the selection of learning, test and validation sets, k-fold validation was applied.
Selection of circuit geometry for miniaturized microwave components based on concurrent optimization of performance and layout area
- Piotr Kurgan
- Sławomir Kozieł
2019 AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS
The paper presents a framework for automated EM-driven circuit geometry selection of miniaturized microwave components. Selection of a particular layout is based directly on miniaturization rates achieved for a set of candidate circuit geometries. Size reduction of the considered structures is obtained by replacing their main building blocks (i.e., conventional transmission lines) with slow-wave composite cells and meander lines. The proposed method primarily aims at minimization of the structure layout area by adjusting all relevant geometry parameters of its compact building blocks. At the same time, the process ensures satisfying the assumed design requirements by means of a penalty function approach. The problem at hand is solved iteratively using a trust-region-embedded gradient search with the Jacobian matrix estimated at the level of a coarse-discretization EM model of individual circuit building blocks for improved computational efficiency. The proposed methodology is verified by two case studies involving branch-line and rat-race couplers. Each design example is considered in eight different layout versions. The miniaturization rates obtained for the considered circuit geometries range between 63.9% and 76% for the first application example, as well as 80.6% and 87.5% for the second one, respectively. Experimental data validate the reliability of the proposed approach.
Selection of derivatisation agents for chlorophenols determination with multicriteria decision analysis
- Marta Bystrzanowska
- Renata Marcinkowska
- Francisco Pena-Pereira
- Marek Tobiszewski
2019 Full text MICROCHEMICAL JOURNAL
The paper shows very systematic method of selection of derivatisation agents for a given group of analytes. In this study 8 derivatisation agents are assessed for their capability to derivatise 8 chlorophenols. Multicriteria decision analysis is used to combine many objectives of derivatisation agents selection into single, easy to be interpreted numerical value. Three basic analyses were performed to obtain rankings with the aims to assess derivatisation reaction, chromatographic separation of derivatised analytes and greenness of derivatisation agents. The first assessment showed acetic anhydride to be the most favourable alternative, the second one indicated N,O‑bis(trimethylsilyl)trifluoroacetamide (BSTFA) - chlorotrimethylsilane (TMCS) mixture to give the best separation and the third proved heptafluorobutyrylimidazole (HFBI) to be the greenest agent. Fourth, comprehensive assessment showed BSTFA:TMCS to have the best total performance. Multicriteria decision analysis can be successfully applied in analytical procedure multi-objective optimisation, at the stage of derivatisation agent selection.
Selection of energy storage units by genetic algorithm for mitigating voltage deviations
- Agata Szultka
- Seweryn Szultka
- Stanisław Czapp
- Jacek Klucznik
2019
In recent years, energy storage units have become very popular. They are applied both for economic and technical purposes. Unfortunately, the cost of such devices is still high and selecting their proper location and rated power have to be performed precisely. In this paper, a Genetic-Algorithm-based optimization method for selecting the best configuration of energy storage units in the power network is proposed. The presented algorithm takes into account the utilization of energy storages which can be used for improving the power network voltage stability in abnormal state of operation of the power network.
Selective adsorption of BTEX on calixarene-based molecular coordination network determined by 13C NMR spectroscopy
- Allana Christina De Oliveira Fros
- Maria Alaide de Oliveira
- Antonia Alice Macedo Soares
- Fernando Hallwass
- Jarosław Chojnacki
- Bráulio Barros
- Severino Júnior
- Joanna Kulesza
2019 Full text INORGANICA CHIMICA ACTA
Benzene, toluene, ethylbenzene, and xylenes (BTEX), a class of volatile organic compounds, are harmful pollutants but also very important precursors in organic industrial chemistry. Among different approaches used for the BTEX treatment, the adsorption technology has been recognized as an efficient approach because it allows to recover and reuse both adsorbent and adsorbate. However, the selective adsorption of the components is the key factor for the efficiency of the process. With this view, calixarene-based materials are very promising due to the unique cavity-like structure of the ligand. An unprecedented coordination network based on calixarene of an interesting nanosheet-like morphology was prepared via a solvothermal layer method. This material showed selectivity for non-polar molecules with remarkable uptake of benzene (38.33 mmol/g). In addition, a simple and useful method of BTEX quantification, through <sup>13</sup>C NMR spectroscopy, is reported here for the first time.
Selectivity of amperometric gas sensors in multicomponent gas mixtures
- Marta Dmitrzak
- Grzegorz Jasiński
- Piotr Jasiński
2019 Full text
In recent years smog and poor air quality became a growing environmental problem. There is a need to continuously monitor the quality of air. The lack of selectivity is one of the most important problems limiting the use of gas sensors for this purpose. In this study, a selectivity of the six amperometric gas sensors is being investigated. Calibration of sensors has been performed in order to find a correlation between concentration level and sensor output. The responses of each sensor to the concentrations from 50 ppb to 1 ppm of selected gases have been measured. Usually, sensors responses are measured only in the presence of one gas. The main goal was to study different interactions between sensors and gases in multicomponent gas mixtures. Sensors were studied under controlled conditions, a constant gas flow rate of 100 mL/min and 50 % relative humidity.
Self-compacting grout to produce two-stage concrete
- Hakim Abdelgader
- Krzysztof Wilde
- A. El-baden
- Marzena Kurpińska
- F. Omidoaf
- Ali M. Rajabi
2019 Full text
Traditional concrete (TC) is primarily composed of a mixture of cement, fine and coarse aggregates, and water. TC is made by mixing together all the components before placing them. Using non-traditional concrete (two-stage concrete) to solve and to eliminate the problem of the aggregate segregation which appears in TC and in the self-compacting concrete. Two-stage concrete (TSC) consists of two main components, namely the grout and coarse aggregate particles. Coarse aggregates are placed into the formwork, and then a fresh grout mixture is injected into the formwork to fill the voids created by the coarse aggregates. The main difference between TC and TSC is the method of preparation and size of aggregates. The described above technology is unique as it allows us to prevent aggregate segregation in a ready mixture. This paper presents the experimental results of preplaced, crushed granite aggregate concreted with five different grout mixture proportions. A total of 48 concrete cylinders were tested in unconfined compression and splitting tension at 28 and 90 days. It was found that splitting tensile strength of the TSC is equivalent or higher than that of TC at the same compressive strength. Splitting tensile strength can be conservatively estimated using the ACI equation for traditional concrete.
Sensitivity analysis as a tool to optimise Human Development Index
- Marta Kuc-Czarnecka
2019 Full text EQUILIBRIUM Quarterly Journal of Economics and Economic Policy
Research background: Composite indicators are commonly used as an approximation tool to measure economic development, the standard of living, competitiveness, fairness, effectiveness, and many others being willingly implemented into many different research disciplines. However, it seems that in most cases, the variable weighting procedure is avoided or erroneous since, in most cases, the so-called ‘weights by belief’ are applied. As research show, it can be frequently observed that weights do not equal importance in composite indicators. As a result, biased rank-ings or grouping of objects are obtained. Purpose of the article: The primary purpose of this article is to optimise and improve the Human Development Index, which is the most commonly used composite indicator to rank countries in terms of their socio-economic development. The optimisation will be done by re-scaling the current weights, so they will express the real impact of every single component taken into consid-eration during HDI’s calculation process. Methods: In order to achieve the purpose mentioned above, the sensitivity analysis tools (mainly the first-order sensitivity index) were used to determine the appropriate weights in the Human Development Index. In the HDI’s resilience evaluation process, the Monte Carlo simulations and full-Bayesian Gaussian processes were applied. Based on the adjusted weights, a new ranking of countries was established and compiled with the initial ranking using, among others, Kendall tau correlation coefficient. Findings & Value added: Based on the data published by UNDP for 2017, it has been shown that the Human Development Index is built incorrectly by putting equal weights for all of its components. The weights proposed by the sensitivity analysis better reflect the actual contribution of individual factors to HDI variability. Re-scaled Human Development Index constructed based on proposed weights allow for better differentiation of countries due to their socio-economic development.
Sensitivity analysis of flexural and torsional buckling loads of laminated columns
- Marcin Kujawa
- Czesław Szymczak
2019 Full text AIP Conference Proceedings
The paper concerns first order sensitivity analysis of flexural and torsional bucklin g loads of axiallycompressed thin-walled columns with bisymmetric or axisymmetric cross-section made of unidirectional fibre-reinforcedlaminate. The first variation of critical loads versus some variations of the column material properties and cross-sectionaldimensions is derived. Numerical examples dealing with simply supported I-columns are presented. The distributions ofsensitivity functions of critical loads are presented with respect to variations of the parameters assumed along the columnaxis are shown. Some differences between sensitivity functions of both kinds of buckling are described and accuracy ofsensitivity analysis in assessment of the critical buckling load changes due to some variations of the column parameters is discussed.
Sensitivity analysis of free torsional vibration frequencies of thin-walled laminated beams under axial load
- Czesław Szymczak
- Marcin Kujawa
2019 Full text CONTINUUM MECHANICS AND THERMODYNAMICS
The paper addresses sensitivity analysis of free torsional vibration frequencies of thin-walled beams of bisymmetric open cross-section made of unidirectional fibre-reinforced laminate. The warping effect and the axial end load are taken into account. The consideration is based upon the classical theory of thin-walled beams of non-deformable cross-section. The first-order sensitivity variation of the frequencies is derived with respect to the design variable variations. The beam cross-sectional dimensions and the material properties are assumed the design variables undergoing variations. The paper includes a numerical example related to simply supported I-beams and the distributions of sensitivity functions of frequencies along the beam axis. Accuracy is discussed of the first-order sensitivity analysis in the assessment of frequency changes due to the fibre volume fraction variable variations, the effect of axial loads is discussed too.
Sensorless field oriented control for five-phase induction motors with third harmonic injection and fault insensitive feature
- Filip Wilczyński
- Patrick Strankowski
- Jarosław Guziński
- Marcin Morawiec
- Arkadiusz Lewicki
2019 Full text Bulletin of the Polish Academy of Sciences-Technical Sciences
The paper presents a solution for sensorless field oriented control (FOC) system for five-phase induction motors with improved rotor flux pattern. In order to obtain the advantages of a third harmonic injection with a quasi-trapezoidal flux shape, two vector models, α1–β1 and α3–β3, were transformed into d1– q1, d3– q3 rotating frames, which correlate to the 1st and 3rd harmonic plane respectively. A linearization approach of the dual machine model in d – q coordinate frames is proposed by introducing a new additional variable “x” which is proportional to the electromagnetic torque. By applying the static feedback control law, a dual mathematical model of the five-phase induction motor was linearized to synthesize a control system in which the electromagnetic torque and the rotor flux can be independently controlled. The results shows the air gap flux shape in steady as well transient states under various load conditions. Moreover, the implemented control structure acquires fault tolerant properties and leads to possible emergency running with limited operation capabilities. The fault-tolerant capability of the analyzed machine was guaranteed by a special implemented control system with a dedicated speed observer, which is insensitive to open-phase fault situation. The experimental tests have been performed with single and double-open stator phase fault. A torque measurement was implemented to present the mechanical characteristics under healthy and faulty conditions of the drive system.
Sensorless low speed PMSM motor control with cogging torque compensation
- Jarosław Guziński
- Marcin Morawiec
- Zbigniew Krzemiński
- Krzysztof Łuksza
- Patrick Strankowski
- Abdellah Kouzou
2019 Full text
The paper presents sensorless control of a low speed permanent magnet synchronous machine with use of modified state observer. An overview of the PMSM motor used in the research setup was presented. The problem of drive torque ripple, resulting mainly from the occurrence of a significant cogging torque, was discussed. A solution compensating the torque ripple of the PMSM motor was proposed. A start-up procedure of the speed control system, allowing to run the drive system without speed and position sensors, was prepared. The field-oriented control with PI controllers of stator currents in the dq axes was implemented. The equations of a new, simplified version of the Krzeminski observer were presented. The observer has simpler structure of the gains, thus it is less computationally-intensive and easier to tune. The experimental results confirming the correct operation of the drive system were shown.
Sensors integration in the smart home environment - a proposal to solve the problem with user identification
- Mariusz Kaczmarek
- Adam Bujnowski
- Kamil Osiński
- Artur Poliński
- Tomasz Kocejko
2019
In this preliminary study we, investigate the possibility of user recognition techniques suitable on smart home devices like chairs, beds, aiming for low–power, high accuracy and quick response time. We propose the two well know technique: voice speaker recognition and accelerometer signal from device mounted on the chair, and the third one optical system basing on IR LED transmitter/receiver circuit. The preliminary results proved that the developed system based on measurement and analysis of the accelerometer signal is very promising and suitable for implementation in the final product. The optical system requires further work but potentially it can be used for user identification purposes.
Sewage sludge pretreatment by low thermal disintegration for better efficacy of sludge digestion process
- Archana Kasinath
- Anna Remiszewska-Skwarek
- Małgorzata Szopińska
- Sylwia Fudala-Książek
- Ewa Zaborowska
- Aneta Łuczkiewicz
2019
The wastewater water treatment plant (WWTP) sector and it is developing technologies strive to be implement circular economy. The methane production from the sludge digestion process constitute promising source of the renewable energy for WWTP and approaching circular economy assumptions. For this reason, the objective of the study was to examine the modification of sludge characteristics due to the low temperature pretreatment. The effect of this pretreatment was evaluated by various parameters, which showed the increase of volatile fatty acids concentration (VFA) (up to ~6g/L) and chemical oxygen demand (COD) value (up to ~15 g/L). Moreover, the disintegration degree (DD), which up to 54% confirm higher bioavailability of organic substances, which can be readily used by methanogenic bacteria. As a consequence a higher methane production during fermentation process was observed
Shales Leaching Modelling for Prediction of Flowback Fluid Composition
- Andrzej Rogala
- Karolina Kucharska
- Jan Hupka
2019 Full text ENERGIES
The object of the paper is the prediction of flowback fluid composition at a laboratory scale, for which a new approach is described. The authors define leaching as a flowback fluid generation related to the shale processing. In the first step shale rock was characterized using X-ray fluorescence spectroscopy, X-ray diractometry and laboratory analysis. It was proven that shale rock samples taken from the selected sections of horizontal well are heterogeneous. Therefore, the need to carry a wide range of investigations for highly diversified samples occurred. A series of leaching tests have been conducted. The extracts were analyzed after leaching to determine Total Organic Carbon and selected elements. For the results analysis significant parameters were chosen, and regression equations describing the influence of rocks and fracturing fluid parameters on the flowback fluid composition were proposed. Obtained models are described by high values of determination coecients with confidence coecients above 0.99 and a relatively low standard deviation. It was proven that the proposed approach regarding shale leaching can be properly described using shale models at a laboratory scale, however scaling up requires further investigations.
Shape-controllable synthesis of GdVO4 photocatalysts and their tunable properties in photocatalytic hydrogen generation
- Paweł Mazierski
- Jakub Sowik
- Magdalena Miodyńska
- Grzegorz Trykowski
- Alicja Mikołajczyk
- Tomasz Klimczuk
- Wojciech Lisowski
- Joanna Nadolna
- Adriana Zaleska-Medynska
2019 DALTON TRANSACTIONS
Novel visible light responsive materials for water splitting are essential for the efficient conversion of solar energy into hydrogen bond energy. Among other semiconductors, gadolinium orthovanadate has appropriate conduction and valence band edges positioned to split water molecules and a narrow band gap that allows the use of visible light for hydrogen generation. Thus, we present here that hydrogen evolution under visible light (λ > 420 nm) could be accomplished using hierarchical 3D GdVO4 particles, obtained by a simple, one pot hydrothermal synthesis. We found that applying various reaction components, such as EDTA-Na2 and EDTA, and adjusting the pH of the solution allow one to tune the shape of GdVO4 (such as short nanowires, long nanowires, short nanorods, long nanorods, nanoparticles and spheres – all having a tetragonal crystal structure) as well as optical and photocatalytic properties. The highest ability to photocatalytically split methanol solution into hydrogen under UV-Vis irradiation was detected for the long nanowire sample (42 μmol h−1), having almost 11 times higher efficiency in comparison with the weakest sample – short nanowires. In addition, GdVO4 spheres generated H2 more than 2 times (5.75 μmol h−1) in comparison with the short nanorod sample (2.5 μmol h−1) under visible light excitation. Photostable in three-hour work cycles, long nanowires and spheres were even able to generate hydrogen from pure water, reaching values of 17 and 3 μmol under UV-Vis and Vis light, respectively.
Shaping the new face of the Imperial Shipyard in Gdańsk
- Piotr Lorens
2019 Full text Przestrzeń i Forma
The main purpose of the article is to present the transformation process of the urban complex known as the Imperial Shipyard in Gdańsk. Its rich history and interesting location on the waterfront of the city as well as its proximity to the very centre makes this area a much sought-after location for the new urban development project, which is part of the wider new district in the city centre of Gdańsk – the Young City. The article presents an outline of the proposed development concept in light of the history of the site and transformation processes of the entire district.
Ship’s de-perming process using coils lying on seabed
- Mirosław Wołoszyn
- Piotr Jankowski
2019 Full text Metrology and Measurement Systems
A ship built from ferromagnetic steel disturbs the uniformity of the Earth’s magnetic field. Changes of ship’s signature are due to the magneto-mechanical interaction of the hull with the Earth’s magnetic field. The ship’s magnetic field can be detected by a magnetic naval mine. For this reason, the vessel has to be demagnetized. There are several methods of ship’s de-perming. The results of experimental and computer simulations of the ship’s de-perming process using coils lying on the seabed are presented in this paper. The simulation of the de-perming process with a hysteresis model of ship’s steel was carried out in Opera3d 18R2. The laboratory experiments were carried out using a physical ship’s model, several Helmholtz coils, magneto-resistive sensors, etc. The experiments and computer simulations have shown that ship’s de-perming with coils lying on the seabed is possi
Shore Construction Detection by Automotive Radar for the Needs of Autonomous Surface Vehicle Navigation
- Stateczny Andrzej
- Kazimierski Witold
- Paweł Burdziakowski
- Weronika Motyl
- Wisniewska Marta
2019 Full text ISPRS International Journal of Geo-Information
Autonomous surface vehicles (ASVs) are becoming more and more popular for performing hydrographic and navigational tasks. One of the key aspects of autonomous navigation is the need to avoid collisions with other objects, including shore structures. During a mission, an ASV should be able to automatically detect obstacles and perform suitable maneuvers. This situation also arises in near-coastal areas, where shore structures like berths or moored vessels can be encountered. On the other hand, detection of coastal structures may also be helpful for berthing operations. An ASV can be launched and moored automatically only if it can detect obstacles in its vicinity. One commonly used method for target detection by ASVs involves the use of laser rangefinders. The main disadvantage of this approach is that such systems perform poorly in conditions with bad visibility, such as in fog or heavy rain. Therefore, alternative methods need to be sought. An innovative approach to this task is presented in this paper, which describes the use of automotive three-dimensional radar on a floating platform. The goal of the study was to assess target detection possibilities based on a comparison with photogrammetric images obtained by an unmanned aerial vehicle (UAV). The scenarios considered focused on analyzing the possibility of detecting shore structures like berths, wooden jetties, and small houses, as well as natural objects like trees or other kinds of vegetation. The recording from the radar was integrated into a single complex radar image of shore targets. It was then compared with an orthophotomap prepared from AUV camera pictures, as well as with a map based on traditional land surveys. The possibility and accuracy of detection for various types of shore structure were statistically assessed. The results show good potential for the proposed approach—in general, objects can be detected using the radar—although there is a need for development of further signal processing algorithms.
Sieciowy Monitor Obiektu – rozproszony system inteligentnego zarządzania złożonymi obiektami przemysłowymi
- Jakub Wszołek
2019 Full text
Celem pracy jest opracowanie kompletnego środowiska pozwalającego na budowę autonomicznych systemów diagnostyki, monitorowania, sterowania i zarządzania inteligentnymi budynkami. W ramach przeprowadzonych prac badawczych przedstawiono opracowaną koncepcję Sieciowego Monitora Obiektu (SMO) oraz metody komunikacji pomiędzy urządzeniami pomiarowo- diagnostyczno-sterującymi w oparciu o wspólną szynę danych Diagnostic Service Bus (zrealizowana w koncepcji Service Oriented Architecure). Częścią środowiska jest dedykowany język (SMOL) opisu funkcji, mechanizmów oraz urządzeń sieciowych. Semantyka języka umożliwia precyzyjne odwzorowanie relacji występujących w rzeczywistym systemie sieciowym. Wynikiem prac badawczo-projektowych jest narzędzie, które pozwala na sprawdzanie możliwości i skuteczności (efektywności) działania dowolnej projektowanej konfiguracji sprzętowej w ściśle określonych warunkach, reprezentowanych przez stosowne kryteria. Zadaniem symulatora jest weryfikacja zasad działania implementowanego systemu SMO (Sieciowego Monitora Obiektu) w rozmaitych konfiguracjach sieciowych. Opracowana platforma symulacyjna umożliwia zamodelowanie, zaprogramowanie oraz przeprowadzenie symulacji całości analizowanej sieci, bądź jej krytycznych fragmentów.