2017 - Repozytorium publikacji - Politechnika Gdańska

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Publikacje z roku 2017

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Damage Analysis of Tensioning Cable Anchorage Zone of a Bridge Superstructure, Using CDP Abaqus Material Model
- Jacek Chróścielewski
- Mikołaj Miśkiewicz
- Łukasz Pyrzowski
- Bartosz Sobczyk
2017 Pełny tekst Archives of Civil Engineering
Numerical analysis of the tensioning cables anchorage zone of a bridge superstructure is presented in this paper. It aims to identify why severe concrete cracking occurs during the tensioning process in the vicinity of anchor heads. In order to simulate the tensioning, among others, a so-called local numerical model of a section of the bridge superstructure was created in the Abaqus Finite Element Method (FEM) environment. The model contains all the important elements of the analyzed section of the concrete bridge superstructure, namely concrete, reinforcement and the anchoring system. FEM analyses are performed with the inclusion of both material and geometric nonlinearities. Concrete Damage Plasticity (CDP) constitutive relation from Abaqus is used to describe nonlinear concrete behaviour, which enables analysis of concrete damage and crack propagation. These numerical FEM results are then compared with actual crack patterns, which have been spotted and inventoried at the bridge construction site.
Damage detection in a bolted lap joint using guided waves
- Rafał Kędra
- Magdalena Rucka
2017 Pełny tekst Procedia Engineering
The paper presents the experimental investigation of guided waves application to the condition assessment of prestressed bolted connections and a concept of new quantitative indicator. The main goal of the research was the analysis of the influence of the contact conditions changes to the characteristics of a propagating disturbance. The experimental tests were carried out for a single bolted lap joint. The excitation and acquisition of elastic waves were performed using piezoelectric plate transducers. The measurements were performed for the gradually increased value of the bolt load, which was controlled by the force washer transducer. The results of tests show the occurrence of relationship between the recorded signals amplitudes or the phase shifts and bolt load values only in initial time period. Therefore, the quantitative analysis of recorded waveforms was performed in the frequency domain based on the power spectral moment theory. Additionally the concept of the modified power spectral moment taking into account the guided wave frequency characteristic has been introduced. The results indicated the possibility of the use of higher order modified power spectral moments for evaluation of the bolted joint condition.
Damage-Involved Structural Pounding in Bridges under Seismic Excitation
- Robert Jankowski
2017 Key Engineering Materials
During severe earthquakes, pounding between adjacent superstructure segments of highway elevated bridges was often observed. It is usually caused by the seismic wave propagation effect and may lead to significant damage. The aim of the present paper is to show the results of the numerical analysis focused on damage-involved pounding between neighbouring decks of an elevated bridge under seismic excitation. The analysis was carried out using a lumped mass structural model with every deck element discretized as a SDOF system. Pounding was simulated by the use of impact elements which become active when contact is detected. The linear viscoelastic model of collision was applied allowing for dissipation of energy due to damage at the contact points of colliding deck elements. The results show that pounding may substantially modify the behaviour of the analysed elevated bridge. It may increase the structural response or play a positive role, and the response depends on pattern of collisions between deck elements. The results also indicate that a number of impacts for a small in-between gap size is large, whereas the value of peak pounding force is low. On the other hand, the pounding force time history for large gap values shows only a few collisions, but the value of peak pounding force is substantially large, what may intensify structural damage.
Data fusion of GPS sensors using Particle Kalman Filter for ship dynamic positioning system
- Krzysztof Jaroś
- Anna Witkowska
- Roman Śmierzchalski
2017
Depending on standards and class, dynamically positioned ships make use of different numbers of redundant sensors to determine current ship position. The paper presents a multi-sensor data fusion algorithm for the dynamic positioning system which allows it to record the proper signal from a number of sensors (GPS receivers). In the research, the Particle Kalman Filter with data fusion was used to estimate the position of the vessel. The presented algorithms generate a virtual measurement using three measurements from independent sensors. The performance of the Particle Kalman Filter algorithm was evaluated in simulation tests for two specific cases: in regular operation and when the signal of one sensor disappears.
DATABASE AND BIGDATA PROCESSING SYSTEM FOR ANALYSIS OF AIS MESSAGES IN THE NETBALTIC RESEARCH PROJECT
- Michał Lewczuk
- Paweł Cichocki
- Józef Woźniak
2017 Pełny tekst TASK Quarterly
A specialized database and a software tool for graphical and numerical presentation of maritime measurement results has been designed and implemented as part of the research conducted under the netBaltic project (Internet over the Baltic Sea – the implementation of a multi-system, self-organizing broadband communications network over the sea for enhancing navigation safety through the development of e-navigation services.) The developed software allows tracing graphs of radio-connections between shore stations and vessels (oﬀshore units), based on historical data including the traffi of ships and their specific parameters collected on the Baltic Sea during the last four years. It also enables preparation of data for network simulation experiments using AIS (Automatic Identification of Ships) and GPS (Global Positioning System) loggers installed on shore stations and vessels, taking into account a number of input parameters, such as: time range, coast station selection, ship flags based on MMSI numbers and types and ranges of possible communication technologies used (WiFi, WiMax, Radwin, LTE, etc.). The created tool has a multi-layer architecture that utilizes the MariaDB SQL database, the Apache2 WEB server, and a number of PHP applications. The runtime environment has been built on Linux Debian version 8 and the HP C7000 cluster of the 16 CPU x86 64 architecture. The modularity of the application allows parallel processing and, therefore, optimization of the computing cluster. The database contains more than 70 million records which enables simulation of various topologies (with multi-hop transmissions) and network operations depending on the transmission techniques being used. The database is fully scalable, and allows easy adding of further data collected during subsequent measurement sessions. Additionally, the use of virtualization tools facilitates the future migration to more effiient processing environments, in case of a significant increase in the volume of data.
Daylight design for urban residential planning in Poland: in regulations and practice. A comparison study of daylight conditions observed in the four neighbouring residential areas
- Natalia Sokół
- Justyna Martyniuk-Pęczek
2017 Pełny tekst
This paper reports on the partial results of the research aiming to illustrate how an integration of daylight design into an architectural planning process can help designers to create the residential buildings in respect to the environmental issues, solar and illuminance gains, as well as, the residents’ needs and comfort. It describes how changing daylight recommendations affected the design of the block of flats regarding their orientation, the spacing, the forms, and a size of the windows in the four urban residential areas. The comparison of daylighting conditions inside these buildings emphasises how the architectural design decisions influenced the quality of life within the investigated regions. The results of this study help to determine the more precise characterisation of daylight indicators useful in architectural planning.
Daylight recommendation for building interiors in the selected national building and lighting regulations in the EU
- Natalia Sokół
- Justyna Martyniuk-Pęczek
2017
The quality of life within building environment is closely linked to the quality of daylight effectively delivered into the living space. The paper describes the results of the normative documents review and a comparative analysis, based on which daylight recommendations present in national regulations have been compiled.
DECISION - MAKING IN VIRTUAL SOFTWARE TEAMS USING CLOUD PLATFORMS
- Beata Krawczyk-Bryłka
- Henryk Krawczyk
2017 Pełny tekst
Software development projects are usually realized by traditional or virtual IT teams using computing clouds. Team collaboration requires decision - making regarding essential aspects of a project progress. The article concerns methods of decision – making process in the case of traditional and virtual teams’ work. The research results conducted in a group of IT specialists are presented, and to analyze their preferences in decision-making methods, four possible cases were tested: hierarchical choice, team members' choice (consensus or voting) and external expert decision. The additional value of the research is the recognition of IT specialists' attitudes towards computing cloud usability in IT projects.
Decision making techniques for electronic communication: an example for Turkey
- Semra Erpolat Tasabat
- Olgun Aydin
2017
Communication is the way for people exchanging information with each other by using various tools. Electronic communication or Ecommunication is the process of sending, receiving and processing information or messages electronically. Electronic communication that is closely related to the development levels of countries, has made considerable progress especially in terms technology, innovation and entrepreneur. In this study, it is investigated whether electronic communication in Turkey is used effectively using the data published by Information and Communication Technologies Authority. For this purpose, different decision making techniques in data mining have beenused. Obtained results are discussed.
DEEP CONVOLUTIONAL NEURAL NETWORKS AS A DECISION SUPPORT TOOL IN MEDICAL PROBLEMS – MALIGNANT MELANOMA CASE STUDY
- Arkadiusz Kwasigroch
- Agnieszka Mikołajczyk
- Michał Grochowski
2017
The paper presents utilization of one of the latest tool from the group of Machine learning techniques, namely Deep Convolutional Neural Networks (CNN), in process of decision making in selected medical problems. After the survey of the most successful applications of CNN in solving medical problems, the paper focuses on the very difficult problem of automatic analyses of the skin lesions. The authors propose the CNN structure and the way to cope with the insufficient number of learning data. The research was carried out and validated on the data base of over 10000 images. The efficiency of the proposed approach reaches 84%.
Deep Features Class Activation Map for Thermal Face Detection and Tracking
- Alicja Kwaśniewska
- Jacek Rumiński
- Paul Rad
2017
Recently, capabilities of many computer vision tasks have significantly improved due to advances in Convolutional Neural Networks. In our research, we demonstrate that it can be also used for face detection from low resolution thermal images, acquired with a portable camera. The physical size of the camera used in our research allows for embedding it in a wearable device or indoor remote monitoring solution for elderly and disabled people. The benefits of the proposed architecture were experimentally verified on the thermal video sequences, acquired in various scenarios to address possible limitations of remote diagnostics: movements of the person performing a diagnose and movements of the examined person. The achieved short processing time (42.05±0.21ms) along with high model accuracy (false positives - 0.43%; true positives for the patient focused on a certain task - 89.2%) clearly indicates that the current state of the art in the area of image classification and face tracking in thermography was significantly outperformed.
Deep neural networks approach to skin lesions classification — A comparative analysis
- Arkadiusz Kwasigroch
- Agnieszka Mikołajczyk
- Michał Grochowski
2017
The paper presents the results of research on the use of Deep Neural Networks (DNN) for automatic classification of the skin lesions. The authors have focused on the most effective kind of DNNs for image processing, namely Convolutional Neural Networks (CNN). In particular, three kinds of CNN were analyzed: VGG19, Residual Networks (ResNet) and the hybrid of VGG19 CNN with the Support Vector Machine (SVM). The research was carried out with the use of database of over 10 000 images representing skin lesions: benign and malignant. Because of an uneven number of images representing different classes of lesions, the up-sampling of underrepresented class was applied. The comparison of the CNN structures with respect to the accuracy, sensitivity and specificity was performed using k-fold validation method.
Degradation of implantable materials – in vivo and in vitro research
- Beata Świeczko-Żurek
- Marcin Wekwejt
- Anna Pałubicka
2017 Pełny tekst European Journal of Medical Technologies
The article concerns the biological and electrochemical degradation of metallic implants in vivo and in vitro studies. The in vivo research dealt with degradation of plates used to join bones, as well as endoprostheses. The most common damages were: metalosis, breaking in the microstructure changes, breaking in area of holes, as well as plastic deformation throughout the length of an implant. The material used for the research was pure titanium. The analysis of the reasons of the damages included the observation of the surface scrap, which was conducted by the use of Philips XL30 electron scanning microscope. In vitro studies concerned the impact of aggressive environments on the external surface of implants. The titanium pins were immersed in the bacterial solution and corrosion tests were carried out in two solutions simulating the human body (Ringer’s and Artificial Saliva). It was found that after a period of 6 months, the bacteria began to settle on the surface. As a results of the electrochemical corrosion processes: general etching, appearance of micropores and intensively corroded areas were observed on the surface. Based on in vivo and in vitro studies, the susceptibility of titanium implants to degradation in the human body is assumed.
Degradation of modified TPS in natural and industrial compost
- Helena Janik
- Maciej Sienkiewicz
- Malwina Wawrowska
- Karolina Wiecierzycka
- Agnieszka Haryńska
2017
The aim of the study was to determine in the pilot studies the degree of decomposition of modified by us thermoplasic starch (potato starch).Commercial and new obtained by us foils were tested in an open roofing at normal weather conditions. The most visible changes were observed in TPS modified by epoxidized soybean oil and arabic gum contrary to commercial foils where there was no mass change observed.
Degradation of reference tyres used for CPX measurements
- Jerzy Ejsmont
- Beata Świeczko-Żurek
- Wojciech Owczarzak
- Sławomir Sommer
- Piotr Mioduszewski
2017
Measurements of tyre/road noise using the Close Proximity Method are based on reference tyres that are described in ISO/TS 11819-3. The standard specifies two tyres, namely "P1" and "H1" that should be used during measurements. To be used for measurements each tyre must fulfill certain conditions that are listed in the standard. The conditions are related to the tread pattern depth and rubber hardness. During experiments performed at the Technical University of Gdańsk (TUG) two identical tyres of "P1" stored in very different condition types were periodically tested for hardness, tyre/road noise and rolling resistance. The paper describes results of the experiments that were carried out for nearly two years.
Dejavniki, ki vplivajo na lokacijo manjših in srednje velikih podjetij v predmestju: primer metropolitanskega območja mest Gdansk, Gdynia in Sopot
- Justyna Martyniuk-Pęczek
- Olga Martyniuk
- Anna Gierusz
- Grzegorz Pęczek
2017 Pełny tekst Urbani izziv
Zaradi pomembne vloge manjših in srednje velikih podjetij (MSP) v evropskem gospodarstvu je ključno ustrezno poznavanje različnih dejavnikov, ki vplivajo na izbiro njihove lokacije. Kljub temu je v teoretičnih in empiričnih raziskavah industrijskih lokacij in urbanističnega načrtovanja velikost podjetij pogosto spregledana. V članku avtorji proučujejo kraj stalnega prebivališča kot dejavnik, ki spodbuja razvoj MSP v predmestjih. To smer razvoja potrjuje tudi multidisciplinarna raziskava, ki so jo izvedli na metropolitanskem območju mest Gdansk, Gdynia in Sopot. Dejavnike, ki vplivajo na lokacijo MSP na predmestnih območjih, so določili z anketo, ki so jo izvedli v 251 podjetjih v 7 občinah z najvišjo stopnjo suburbanizacije na proučevanem metropolitanskem območju. Raziskava je potrdila, da je za občine, v katerih potekajo najintenzivnejši procesi suburbanizacije, značilna višja stopnja poslovne dejavnosti. Lastniki podjetij odločitve o lokaciji podjetja večinoma sprejemajo v skladu z načeli vedenjske teorije. To pomeni, da pri svojih odločitvah pogosteje upoštevajo osebne dejavnike kot stroške ali povpraševanje. Zanje so najpomembnejši dejavniki življenjske razmere, kakovost javnega prostora, izobrazba in zdravstvo.
DEM ANALYSIS OF EFFECT OF INTERFACIAL TRANSITIONAL ZONES ON FRACTURE IN CONCRETE.
- Michał Nitka
- Andrzej Tejchman-Konarzewski
2017 Photonics and Nanostructures-Fundamentals and Applications
Artykuł omawia wyniki numeryczne dotyczące pękania betonu uzyskane stosując metodę elementów dyskretnych. Trójwymiarowe obliczenia wykonano dla próbek betonowych podczas zginania. Beton został opisany jako model 4-fazowy. Mikrostrukturę betonu przyjęto na podstawie 3D zdjęć mikro-tomograficznych. Zbadano wpływ stref przejściowych na wytrzymałość i proces pękania. Wyniki numeryczne zostały porównane z wynikami doświadczalnymi. Uzyskano bardzo dobrą zgodność między wynikami numerycznymi i doświadczalnymi.
Deposition of phosphate coatings on titanium within scaffold structure
- Bartłomiej Trybuś
- Andrzej Zieliński
- René Beutner
- Tomasz Seramak
- Dieter Scharnweber
2017 Pełny tekst Acta of Bioengineering and Biomechanics
Purpose: Existing knowledge about the appearance, thickness, and chemical composition of phosphate coatings on titanium inside porous structures is insufficient. Such knowledge is important for the design and fabrication of porous implants. Methods: Metallic scaffolds were fabricated by selective laser melting of 316L stainless steel powder. Phosphate coatings were deposited on Ti sensors placed either outside the scaffolds or in the holes in the scaffolds. The electrochemically-assisted cathodic deposition of phosphate coatings was performed under galvanostatic conditions in an electrolyte containing the calcium and phosphate ions. The phosphate deposits were microscopically investigated; this included the performance of mass weight measurements and chemical analyses of the content of Ca2+ and 2 PO4 ions after the dissolution of deposits. Results: The thicknesses of the calcium phosphate coatings were about 140 and 200 nm for isolated titanium sensors and 170 and 300 nm for titanium sensors placed inside pores. Deposition of calcium phosphate occurred inside the pores up to 150 mm below the scaffold surface. The deposits were rich in Ca, with a Ca/P ratio ranging from 2 to 2.5. Conclusions: Calcium phosphate coatings can be successfully deposited on a Ti surface inside a model scaffold. An increase in cathodic current results in an increase in coating thickness. Any decrease in the cathodic current inside the porous structure is slight. The calcium phosphate inside the pores has a much higher Ca/P ratio than that of stoichiometric HAp, likely due to a gradual increase in Ca fraction with distance from the surface.
Deregulacja polskiego rynku pracy
- Małgorzata Gawrycka
2017 Pełny tekst Studia Ekonomiczne. Zeszyty Naukowe Uniwersytetu Ekonomicznego w Katowicach
Historycznie ukształtowana regulacja rynku pracy związana jest z jego infrastrukturą organizacyjno-prawną, tzn. przepisami dotyczącymi płac, czasu pracy i ochrony stosunku pracy. W opinii zwolenników deregulacji utrudnia ona elastyczne dostosowywanie się do rozmiarów zatrudnienia w zależności od zaistniałej sytuacji gospodarczej, powodując wzrost bezrobocia strukturalnego i wzrost kosztów pracy. Deregulacja rynku pracy związana jest z rozluźnieniem istniejących ograniczeń ustawowych norm w zakresie stosunków pracy, czasu pracy, płac, realizowaną polityką zatrudnienia w przedsiębiorstwach. Celem niniejszego opracowania jest zbadanie, w jaki sposób deregulacja polskiego rynku pracy po roku 2004 wpłynęła na zmiany w poziomie i formach zatrudnienia w gospodarce narodowej.
Deregulation of the labour markets in the countries of Central and Eastern Europe — selected issues
- Małgorzata Gawrycka
2017 Pełny tekst Public Policy and Administration
The countries of Central and Eastern Europe in the 1990s pursued the transformation processes which were to result in introducing systemic changes and building market economies. It was a process requiring adjustment of the regulatory and system framework to the requirements of the EU. One of the areas covered by the changes was the labour market. The reforms related to the functioning of national labour markets necessitated taking many decisions, often difficult ones, as they were associated with incurring high social costs. The aim of this study is to examine how the processes of labour legislation deregulation influenced the situation in the labour markets of individual countries of Central and Eastern Europe, and in particular their employment levels. The study was based on data from years 2004 and 2015. The study used available Eurostat statistics databases. Elements of descriptive statistics were also used as a tool.