Publications Repository - Gdańsk University of Technology

Page settings

polski
Publications Repository
Gdańsk University of Technology

Show publications from the year

Recent items

  • Influence of the Delay in Monitor System on the Motor Coordination of Musicians while Performing
    • Szymon Zaporowski
    • Maciej Blaszke
    • Dawid Weber
    • Marta Stefaniak
    2019

    This paper provides a description and results of measurements of the maximum acceptable value of delay tolerated by a musician, while playing an instrument, that does not cause de-synchronization and discomfort. First, methodology of measurements comprising audio recording and a fast camera is described. Then, themeasurement procedure for acquiring the maximum value of delay conditioning comfortable playing is presented. Results of musician’s response while playing an instrument along with a delayed signal reproduced from the monitor system are shown. Finally, a presentation of the highest values of delays for musicians playing different instruments is given along with a detailed discussion on the methodology used

  • Influence of the electrosynthesis conditions on the spontaneous release of anti-inflammatory salicylate during degradation of polypyrrole coated iron for biodegradable cardiovascular stent
    • Karolina Cysewska
    • Jakub Karczewski
    • Piotr Jasiński
    2019 ELECTROCHIMICA ACTA

    In this work, the spontaneous release of anti-inflammatory salicylate from polypyrrole (PPy) coated iron has been studied during degradation of the material in phosphate buffer saline at 37 C. The sodium salicylate was incorporated into PPy in a one-step electropolymerization process. The influence of the synthesis conditions such as sodium salicylate concentration, pyrrole concentration and deposition charge on drug release profile has been investigated. The morphology, surface roughness and redox properties of PPy/Fe have been also studied. The drug release was studied by UV-Vis spectrophotometer with flow cuvette connected to the electrochemical cell, which provided continuous study of the released dopant. As a result, reliable and quantitative study of salicylate release from PPy coated iron was attained.Depending on the synthesis conditions the concentration of the salicylate released was in the range of 83-183 mM/cm2 after 21 h of immersion. The rate of drug release of 10-11mM/h was the highest at the beginning after immersion (1-2 h), then it gradually decreased and finally it reached the lowest value of approximately 0.3 mM/h at the end of the process.

  • Influence of the ionic strength on the amyloid fibrillogenesis of hen egg white lysozyme
    • Jarosław Wawer
    • Michał Szociński
    • Marcin Olszewski
    • Rafał Piątek
    • Mateusz Naczk
    • Joanna Krakowiak
    2019 INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES

    The study investigates the role of the electrostatic interactions in the fibrillation of the hen egg white lysozyme (HEWL). In order to achieve this aim the influence of the cations Na+, Mg2+ and Al3+ on the amyloid fibril formation and amorphous aggregation was tested. The amyloids are formed in the solution without added salt but the Thioflavin T fluorescence gives the false-negative result. In these conditions, the HEWL fibrils are long and curvy. If the ionic strength of the solution is sufficiently high, the formed amyloids are shorter and fragmented. Our study shows that the addition of the aluminium salt promotes protein fibrillation. The amorphous aggregation dominates in the high concentration of electrolyte. The in vitro amyloid fibril formation seems to be regulated by universal mechanisms. The theories implemented in the polymer science or for colloidal solutions give the qualitative description of the aggregation phenomena. However, the specific interactions and the additional effects (e.g. fibril fragmentation) modulate the amyloidogenesis.

  • Influence of the low ambient temperature on the start-up process of hydraulic pumps
    • Ryszard Jasiński
    2019

    Starting hydraulic pumps in low ambient temperatures may cause: decreased hydraulic-mechanical efficiency, larger vibration of hydraulic installation, faster wear and more frequent damage to the elements of pumps, change of material properties of elements, increase of pressure drop. As a result of pressure drop in the suction pipe, large underpressure may be experienced, causing incomplete filling of pump working chambers with oil and reducing volumetric efficiency. Starting of cooled hydraulic pump in low temperatures may occur when pump is supplied either with oil of the same ambient temperature or with the oil warmed to higher temperature. During start-up of a hydraulic pump in thermal shock conditions, parts warm up in a nonuniform way, due to varying material and shape properties. This causes change of clearances between the co-operating elements and may lead to faulty operation of hydraulic pump or to its break-down. Experimental tests of pumps during start-up in low ambient temperatures, were performed in the Hydraulics Laboratory of the Faculty of Mechanical Engineering of the Gdańsk University of Technology. The Laboratory is equipped with multipump supply devices with oil temperature stabilization, devices for testing hydraulic components as well as a system for measuring and recording mechanical, hydraulic and thermal quantities. In low temperature chamber it was possible to cool down hydraulic components to –25 °C. The supply oil temperature was kept in the range from 20 to 60 °C (usually at 50 °C) by means of oil temperature stabilizing system.

  • Influence of the shoe type on the ground reaction forces
    • Małgorzata Klepczyńska
    • Bartłomiej Zagrodny
    • Wiktoria Wojnicz
    • Michał Ludwicki
    • Jan Awrejcewicz
    2019 Full text

    The aim of this work was to estimate a relationship between the type of the footwear and ground reactions. Differences in medio-lateral, anterior-posterior and vertical reactions are compared for different shoe-types for male and female volunteers. Each of the participants gait was recorded in case of different shoes and without them, also stabilograms were analyzed. Results revealed differences in ground reaction forces for different shoe-types and its influence on static stability.

  • Influence of Thermal Imagery Resolution on Accuracy of Deep Learning based Face Recognition
    • Maciej Szankin
    • Alicja Kwaśniewska
    • Jacek Rumiński
    2019 Full text

    Human-system interactions frequently require a retrieval of the key context information about the user and the environment. Image processing techniques have been widely applied in this area, providing details about recognized objects, people and actions. Considering remote diagnostics solutions, e.g. non-contact vital signs estimation and smart home monitoring systems that utilize person’s identity, security is a very important factor. Thus, thermal imaging has become more and more popular, as it does not reveal features that are often used for person recognition, i.e. sharp edges, clear changes of pixel values between areas, etc. On the other hand, there are much more visible light data available for deep model training. Taking it into account, person recognition from thermography is much more challenging due to specific characteristics (blurring and smooth representation of features) and small amount of training data. Moreover, when low resolution data is used, features become even less visible, so this problem may become more difficult. This study focuses on verifying whether model trained to extract important facial embedding from RGB images can perform equally well if applied to thermal domain, without additional re-training. We also perform a set of experiments aim at evaluating the influence of resolution degradation by down-scaling images on the recognition accuracy. In addition, we present deep super-resolution (SR) model that by enhancing donw-scaled images can improve results for data acquired in scenarios that simulate real-life environment, i.e. mimicking facial expressions and performing head motions. Preliminary results proved that in such cases SR helps to increase accuracy by 6.5% for data 8 times smaller than original images. It has also been shown that it is possible to accurately recognize even 40 volunteers using only 4 images per person as a reference embedding. Thus, the initial profiles can be easily created in a real time, what is an additional advantage considering a solution setup in a new environment.

  • INFLUENCE OF WRONGLY ASSUMED PROBABILITY DISTRIBUTION ON THE UNCERTAINTY OF RESISTANCE MEASUREMENT BY TECHNICAL METHOD
    • Stanisław Szczesny
    • Anna Golijanek-Jędrzejczyk
    • Dariusz Świsulski
    2019 Full text Poznan University of Technology Academic Journals. Electrical Engineering

    The paper presents studies on the influence of probability distributions on the expanded uncertainty of the resistance measurement. Choosing the correct probability distribution is very important to estimate of measurement uncertainty. The most commonly used distribution is the rectangular distribution. The paper presents the results of analysis of the resistance measurement uncertainty using the technical method of two resistances: 1 Ω and 100 GΩ using different measuring equipment. The analysis of the uncertainty measurement of resistance was carried out repeatedly, each time assuming a different probability distribution of measuring instruments (normal, rectangular, triangular or trapezoidal). The results of the research presented in the article show that the influence of the assumed probability distributions on the result of the measurement uncertainty analysis is significant and results discrepancies can reach up to 30%.

  • Influence of YARN Schedulers on Power Consumption and Processing Time for Various Big Data Benchmarks
    • Krzysztof Drypczewski
    • Jerzy Proficz
    • Andrzej Stepnowski
    2019 Full text TASK Quarterly

    Climate change caused by human activities can influence the lives of everybody onthe planet. The environmental concerns must be taken into consideration by all fields of studyincludingICT. Green Computing aims to reduce negative effects of IT on the environment while,at the same time, maintaining all of the possible benefits it provides. Several Big Data platformslike Apache Spark orYARNhave become widely used in analytics and High-PerformanceComputing systems due to the reliability and usability of Map Reduce implementations. Theauthors research the power consumption and energy efficiency of HadoopYARNschedulers usingApache Spark under three different workloads. The test cases include: sorting large binary files,counting unique words in large text files and processing satellite imagery from the Sentinel-2mission. The presented results show small (2%–11%) but distinct differences in the powerconsumption ofFIFOandFAIRschedulers

  • INFOGEST static in vitro simulation of gastrointestinal food digestion
    • André Brodkorb
    • Lotti Egger
    • Marie Alminger
    • Paula Alvito
    • Ricardo Assunção
    • Simon Ballance
    • Torsten Bohn
    • Claire Bourlieu-Lacanal
    • Rachel Boutrou
    • Frédéric Carrière
    • Alfonso Clemente
    • Milena Corredig
    • Didier Dupont
    • Claire Dufour
    • Cathrina Edwards
    • Matt Golding
    • Sibel Karakaya
    • Bente Kirkhus
    • Steven Le
    • Uri Lesmes
    • Adam Macierzanka
    • Alan Mackie
    • Carla Martins
    • Sébastien Marze
    • David McClements
    • Olivia Ménard
    • Mans Minekus
    • Reto Portmann
    • Cláudia Santos
    • Isabelle Souchon
    • R Singh
    • Gerd Vegarud
    • Martin Wickham
    • Werner Weitschies
    • Isidra Recio
    2019 Full text Nature Protocols

    Developing a mechanistic understanding of the impact of food structure and composition on human health has increasingly involved simulating digestion in the upper gastrointestinal tract. These simulations have used a wide range of different conditions that often have very little physiological relevance, and this impedes the meaningful comparison of results. The standardized protocol presented here is based on an international consensus developed by the COST INFOGEST network. The method is designed to be used with standard laboratory equipment and requires limited experience to encourage a wide range of researchers to adopt it. It is a static digestion method that uses constant ratios of meal to digestive fluids and a constant pH for each step of digestion. This makes the method simple to use but not suitable for simulating digestion kinetics. Using this method, food samples are subjected to sequential oral, gastric and intestinal digestion while parameters such as electrolytes, enzymes, bile, dilution, pH and time of digestion are based on available physiological data. This amended and improved digestion method (INFOGEST 2.0) avoids challenges associated with the original method, such as the inclusion of the oral phase and the use of gastric lipase. The method can be used to assess the endpoints resulting from digestion of foods by analyzing the digestion products (e.g., peptides/amino acids, fatty acids, simple sugars) and evaluating the release of micronutrients from the food matrix. The whole protocol can be completed in ~7 d, including ~5 d required for the determination of enzyme activities.

  • Informatyka medyczna jako dyscyplina naukowa i usługowa
    • Antoni Nowakowski
    2019

    Omówiono zakres tematyczny części I monografii, trochę historii i zakres działalności promocyjnej, publikacyjnej, normalizacyjnej i edukacyjnej w informatyce medycznej.

  • INFORMATYKA MEDYCZNA W PROGRAMACH NAUCZANIA
    • Antoni Nowakowski
    • Jacek Rumiński
    • Mariusz Kaczmarek
    2019

    Rozdział prezentuje zakres realizacji informatyki medycznej w programach nauczania na krajowych uczelniach. Po wstępie historycznym, skupia się na omówienie informatyki medycznej jako wydzielonego obszaru kształcenia. Następnie prezentuje jako przykład zagadnienia związane z kształceniem studentów w tym obszarze na Politechnice Gdańskiej.

  • Injectable poloxamer/graphene oxide hydrogels with well‐controlled mechanical and rheological properties
    • Elaheh Rohani
    • Henri Vahabi
    • Krzysztof Formela
    • Mohammad Saeb
    • Sabu Thomas
    2019 POLYMERS FOR ADVANCED TECHNOLOGIES

    Although significant progress has been made in the design and application of injectable hydrogels for biomedical applications, concurrent control of rheological and mechanical properties of injectable hydrogels has remained as an open challenge to the researchers. In this work, we introduce and put into practice a photo‐curable poloxamer (also known as Pluronic)/graphene oxide (Plu/GO) injectable hydrogel with well‐controlled rheological and mechanical properties. Acrylate group was anchored to hydrogel structure to endow photo‐crosslinking ability through decelerating degradation rate of poloxamer hydrogels after injection. It was found that the modified Plu remains stable in biological media for a long‐term period without significant weight loss. Rheological properties of hydrogels were also carried out as essential prerequisite for an ideal injectability via frequency sweep, flow curve, recovery, and yield stress before and after modification, signifying shear‐thinning behavior of Plu/GO hydrogels with high recoverability. The viscosity of shear‐thinning‐like hydrogels dropped at higher shear stress, which facilitated injection process. Moreover, mechanical behavior of Plu was optimized by manipulating the content of Plu, degree of modification with reactive precursor, curing, and particularly incorporation of GO without deteriorating effects on rheological behavior of Plu.

  • Injury Prediction Models for Onshore Road Network Development
    • Wojciech Kustra
    • Joanna Żukowska
    • Marcin Budzyński
    • Kazimierz Jamroz
    2019 Full text Polish Maritime Research

    Integrating different modes of transport (road, rail, air and water) is important for port cities. To accommodate this need, new transport hubs must be built such as airports or sea ports. If ports are to grow, they must be accessible, a feature which is best achieved by building new roads, including fast roads. Poland must develop a network of fast roads that will provide good access to ports. What is equally important is to upgrade the network of national roads to complement fast roads. A key criterion in this case is to ensure that the roads are efficient to minimise time lost for road users and safe. With safety standards and safety management practices varying vastly across the EU, Directive 2008/96/EC of the European Parliament and of the Council was a way to ensure that countries follow procedures for assessing the impact of road projects on road safety and conduct road safety audits, road safety management and road safety inspections. The main goal of the research was to build mathematical models to combine road safety measures, i.e. injury density (DI) and accident density (DA), with road and traffic factors on longer sections, all based on risk analysis. The practical objective is to use these models to develop tools for assessing how new road projects will impact road safety. Because previous research on models to help estimate injuries (I) or injury density (DI) on long sections was scarce, the authors addressed that problem in their work. The idea goes back to how Poland is introducing procedures for assessing the effects of infrastructure on safety and developing a method to estimate accident indicators to support economic analysis for new roads, a solution applied in JASPERS. Another reason for the research was Poland’s insufficient and ineffective pool of road safety management tools in Poland. The paper presents analyses of several models which achieved satisfactory results. They are consistent with the work of other researchers and the outcomes of previous research conducted by the authors.

  • Innovative method of localization airplanes in VCS (VCS-MLAT) distributed system
    • Szymon Wiszniewski
    2019

    The article presents the concept and the structure of the localization module. The prototype module is the part of the VCS (VCS-MLAT) localization distributed system. The device receives the audio signal transmitted in airplanes band (118 MHz – 136 MHz). Received data with the timestamps are send to the main server. The data from multiple devices estimates the localization of the airplane. The main aim of the project is the analysis of the innovative airplane localization method in the close to real environment, based on the audio signal transmitted in 118 MHz – 136 MHz band. The development work requires elaboration and implementation of the prototypes of the distributed system. This concept will increase security in civil and military aviation in the situation when the rests localization systems failed. The localization module as a part of the VCS localization system contains: motherboard with System on Chip integrated circuit, analog radiostation, GPS receiver and ADS-B receiver. The audio signal received from radiostation is sampled and send with the timestamps synchronized by the GPS module to the main server. Moreover, the verification of proper working VCS-MLAT system will be provided by ADS-B receiver. The special software in the main VCS system server is responsible for the estimation of aircraft position with the cooperation of dedicated localization modules, which are placed on monitored area. The concept of radiolocalization system based on the VCS communication structure should be considered as unique, compared to actual systems.

  • Innovative Research Into Road Restraint Systems
    • Kazimierz Jamroz
    • Krzysztof Wilde
    • Marcin Budzyński
    • Łukasz Jeliński
    • Jacek Chróścielewski
    • Stanisław Burzyński
    • Łukasz Pachocki
    2019 Full text Journal of KONBiN

    Key to understanding the needs and building road infrastructure management tools to prevent and mitigate run-off-road accidents is to identify hazards and their sources which are a result of wrong design, construction, installation and maintenance of road restraint systems [1]. Building such tools requires advanced studies with field tests, simulations and models to demonstrate the effects of selected parameters on road user safety [2]. Delivered under the Road Innovation programme, two research projects (ROSE and LifeROSE) are designed to help with that. The main aim of the pro-jects is to develop a method to help with an optimal choice of road restraint systems depending on the type and level of hazard, road class, size and structure of vehicle streams and driving condi-tions (vehicle speed) on the road. To that end a number of field tests were carried out designed to identify hazards and build a database of road elements. The article presents a general characteris-tics of the study, fieldwork and simulation and analytical tests required to meet the objectives. It also gives a detailed description of the crash tests conducted in the field for the two projects. A series of crash tests involving vehicles and barriers was carried out to assess how the selected restraint systems behaved and, as a result, to identify how selected barrier design factors and dy-namic vehicle factors affect the functional features of safety barriers under investigation.

  • INNOWACYJNA METODA WZMOCNIENIA PRZYCZÓŁKA WIADUKTU PRZY UŻYCIU INIEKCJI GEOPOLIMEROWYCH
    • Anna Banaś
    • Lech Bałachowski
    • Andrzej Kuryłowicz
    • Andrzej Kowalik
    • Agnieszka Poteraj - Oleksiak
    • Cezary Witas
    2019 Full text

    W obecnych czasach szybki rozwój infrastruktury i nowoczesnych technologii niejednokrotnie narzuca projektantom oraz wykonawcom takie rozwiązania, aby prowadzone roboty budowlane, były jak najmniej uciążliwe dla uczestników ruchu i jak najmniej ingerowały w system komunikacyjny. Dotyczy to zarówno budowy nowych obiektów jaki i remontu obiektów już istniejących. W niniejszej pracy przedstawiono nowatorską koncepcję remontu wiaduktu w ciągu Drogi Krajowej nr 12 nad torami PKP w miejscowości Podbór. Został on wybudowany w latach 50-tych jako żelbetowa rama. Problemem, który występował podczas eksploatacji obiektu i prowadził do potrzeby pilnej oraz jak najmniej inwazyjnej jego naprawy było nadmierne osiadanie nasypu za przyczółkiem. Spowodowało ono przemieszczenie urządzenia dylatacyjnego aż o 30 mm a tym samym prowadziło do jego uszkodzenia. Pierwszy raz w Polsce wykonano wzmocnienie przyczółka wiaduktu przy użyciu iniekcji geopolimerowych, które w znaczący sposób ograniczyło czas przeznaczony na wprowadzane ograniczenia w ruchu kołowym, a tym samym skróciło czas samej inwestycji. Zastosowanie nowatorskiej technologii pozwoliło na prowadzenie robót, tak aby były one jak najmniej uciążliwe dla uczestników ruchu. W standardowym podejściu, wymiana gruntu nasypowego i ponowne zagęszczenie, wymagałoby wprowadzenia zamknięć ruchu na całym odcinku na minimum trzy miesiące, znacząco utrudniając komunikację.

  • Innowacyjne metody obróbki powierzchni płaskich na docierarkach
    • Adam Barylski
    2019

    Przedstawiono charakterystykę innowacyjnej technologii obróbki powierzchni płaskich i płasko-równoległych na docierarkach jedno- i dwutarczowych. Zamieszczono studium przypadku obejmującego obróbkę elementów ceramicznych i wykonanych z węglików spiekanych, analizując jakość szlifowanych powierzchni i czasochłonność operacji oraz koszty obróbki elementów płaskich w układzie dwutarczowym.

  • In-plane shear nonlinearity in failure behavior of angle-ply laminated shells
    • Agnieszka Sabik
    2019 COMPOSITE STRUCTURES

    The paper concerns the progressive failure analysis of laminates with the in-plane shear nonlinearity accounted for.The nonlinear shear response of the layer is described by the constitutive relation treating the stresses as a function of strains. Thus it can be easily incorporated into the displacement-based FEM codes. The brittle failure mechanisms of the fibers and the matrix of the layer are recognized with the use of the Hashin criterion. The model is implemented into the non-commercial FEM program for the analysis of multifold shells which is based on the 6-parameter nonlinear shell theory of the Cosserat type.

  • In-situ Cu-doped MnCo-spinel coatings for solid oxide cell interconnects processed by electrophoretic deposition
    • A Sabato
    • Sebastian Molin
    • H. Javed
    • E Zanchi
    • A Boccaccini
    • F Smeacetto
    2019 CERAMICS INTERNATIONAL

    The Cu doping of the Mn–Co spinel is obtained “in-situ” by electrophoretic co-deposition of CuO and Mn1.5Co1.5O4 powders and subsequent two-step reactive sintering. Cu-doped Mn1.5Co1.5O4 coatings on Crofer22APU processed by electrophoretic co-deposition method are tested in terms of long term oxidation resistance and area specific resistance tests up to 3600 h. The introduction of Cu in the spinel lead to higher level of densification of coatings for all the considered aging periods at 800 °C and stabilizes the cubic phase of the Mn1.5Co1.5O4 spinel. Corrosion rate of the Cu-doped Mn1.5Co1.5O4 coated Crofer22APU is ∼10x lower than for the uncoated Crofer22APU. The stabilization of the cubic phase due to Cu doping, which reduces the extent of the tetragonal-cubic phase transition and limits possible thermal stresses due to mismatch of coefficients of thermal expansion or volume changes, is reviewed and discussed by means of electrical conductivity measurements together with diffraction patterns and elemental analyses. These novel electrophoretic co-deposited Cu-doped MnCo spinel coatings represent an innovative approach to obtain coatings with higher density and have future applications in the view of reaching lower rates of Cr evaporation form the steel.

  • In-situ monitoring of electropolymerization processes at boron-doped diamond electrodes by Mach-Zehnder interferometer
    • Michał Sobaszek
    • Marcin Strąkowski
    • Łukasz Skowroński
    • Siuzdak Katarzyna
    • Sawczak Mirosław
    • Igor Własny
    • Andrzej Wysmołek
    • Aleksandra Wieloszyńska
    • Jerzy Pluciński
    • Robert Bogdanowicz
    2019 Full text SENSORS AND ACTUATORS B-CHEMICAL

    In this work, the Mach-Zehnder interferometer was designed to monitor the electrochemical processes conducted at boron-doped diamond electrode surface. The diamond electrodes were synthesized via Microwave Plasma-Assisted Chemical Vapor Deposition on optical grade quartz glass. The achieved transmittance in working are of diamond electrodes reached 55 %. A cage system-based Mach-Zehnder interferometer was used which allowed the insertion of thin-layer electrochemical cells. Electrochemical studies were carried out in a thin-layer working cell. The application of such setup, allows to combine optical monitoring of surface of the working electrode during electrochemical measurements, electropolymerization or surface modification. The conducted investigation shows that during surface modification by melamine the phase shift is up to 0.0328 μm−1. The aforementioned set up can be applied for in situ monitoring of surface modifications with various compounds, and to detect organic substances whose oxidation or reduction products absorb onto the electrode surface.

  • Instalacja artystyczna "W sztuce lubię: romantyzm, poezję i figle"
    • Patryk Różycki
    2019

    Instalacja artystyczna "W sztuce lubię: romantyzm, poezję i figle" instalacja z 70 koszul męskich różnego koloru, wraz z wideo wyświetlanym na suficie. Wystawa w Instytucie Cybernetyki Sztuki.

  • Installation of Compensators in the Power System Transmission Grid
    • Ryszard Zajczyk
    • Robert Kowalak
    • Artur Zbroński
    2019 Full text Acta Energetica

    The article discusses issues of reactive power compensation in transmission grids, with particular focus on the selection of compensator locations and basic parameters. Attention was focused on modern power electronics systems that ensure full automatic compensator adjustment to voltage or power criteria.

  • Installation of GNSS receivers on a mobile railway platform – methodology and measurement aspects
    • Paweł Dąbrowski
    • Cezary Specht
    • Władysław Koc
    • Andrzej Wilk
    • Krzysztof Czaplewski
    • Krzysztof Karwowski
    • Mariusz Specht
    • Piotr Chrostowski
    • Jacek Szmagliński
    • Sławomir Grulkowski
    2019 Full text Zeszyty Naukowe Akademii Morskiej w Szczecinie

    Determining the course of a railway track axis using satellite methods relies on ensuring the precise assembly of GNSS receivers in dedicated measuring devices. Depending on the number of receivers, solutions that are based on placing the apparatus directly above the railway track axis (as well as in eccentric positions) are used to indirectly obtain data to form the basis of the desired results. This publication describes the installation of five GNSS receivers on a mobile measuring platform as part of the InnoSatTrack project. The methodology and the procedure of the geodetic measurements required to obtain the geometrical configuration of the measuring apparatus, specified in the technical project, are presented. The publication presents the principles of total station measurement methods as well as the steps taken to achieve precise results from staking out. The process of acquiring the same configuration of the GNSS receivers, based on the geometry of the squares on the two measuring platforms that were used in the research, has been shown. The final determination of the position of the receivers did not exceed an error of 0.010 m with an average error of 0.003 m, despite the occurrence of mounting difficulties. The results have demonstrated the high credibility and effectiveness of the presented solution.

  • Integrated approach for functional safety and cyber security management in maritime critical infrastructures
    • Marcin Śliwiński
    • Emilian Piesik
    2019 Full text Journal of Polish Safety and Reliability Association, Summer Safety and Reliability Seminars

    The work is devoted important issues of the management in maritime critical infrastructure of functional safety analysis, in particular the safety integrity level (SIL) verification of safety functions to be implemented within the distributed control and protection systems with regard to cyber security aspects. A method based on quantitative and qualitative information is proposed for the SIL (IEC 61508, 61511) verification with regard of the evaluation assurance levels (EAL) (ISO/IEC 15408), the security assurance levels (SAL) (IEC 62443), and the number of protection rings described in the SecureSafety (SeSa-SINTEF) methodology. The proposed approach will be composed of the following items: process and procedure based safety and cyber security management, integrated safety and security assessment of industrial control system (ICS) of the maritime critical infrastructure. Proposed methodology is illustrated on case study that based on the part of installation critical maritime infrastructure..

  • INTEGRATED FUNCTIONAL SAFETY AND CYBERSECURITY ANALYSIS METHOD FOR SMART MANUFACTURING SYSTEMS
    • Kazimierz Kosmowski
    • Marcin Śliwiński
    • Jan Piesik
    2019 Full text TASK Quarterly

    This article addresses integrated functional safety and cybersecurity analysis with regard to: the generic functional safety standard IEC 61508 and the cyber security standard IEC 62443 concerning an industrial automation and control system (IACS). The objective is to mitigate the vulnerability of information technology (IT) and operational technology (OT) systems, and reduce relevant risks taking into account a set of fundamental requirements (FRs). A method is proposed for determining and verifying the performance level (PL) or the safety integrity level (SIL) of defined safety functions, and then validating these levels depending on the security level (SL) of a particular domain, e.g. a safety related control system (SRCS). The method is general in the sense that it is based on risk graphs prepared for individual risk and/or societal/group risk with regard to the criteria defined.

  • Integrated Photocatalytic Advanced Oxidation System (TiO2/UV/O3/H2O2) for Degradation of Volatile Organic Compounds
    • Andre Fernandes
    • Michał Gągol
    • Patrycja Makoś
    • Javed Ali
    • Grzegorz Boczkaj
    2019 Full text SEPARATION AND PURIFICATION TECHNOLOGY

    Several advanced oxidation processes (AOPs) including photocatalytic processes were studied for effective treatment of complex model wastewater containing a wide variety of VOCs. The studies revealed synergistic effects of TiO2 based processes for improved degradation of the VOCs. A peroxone combined with TiO2/UV system (TiO2/UV/O3/H2O2) with a ratio between the oxygen source from the oxidant to chemical oxygen demand (COD) of the model wastewater (rox) of 0.5 and 100 mgTiO2/L was the optimal process. TiO2 revealed to be economically reasonable to be used in TiO2/UV/H2O2 and TiO2/UV/O3/H2O2 photocatalytic technologies for efficient and fast (100 min) degradation of VOCs with significantly low amounts of chemicals. Developed system provide high effectiveness with low treatment cost, which in case of most VOCs studied provide satisfactory effects in 15 min. of treatment process with 4 $/m3 of process costs. The technologies are promising in degradation and purification in several types of industrial effluents with a high VOCs content.

  • Integration, Processing and Dissemination of LiDAR Data in a 3D Web-GIS
    • Marek Kulawiak
    • Marcin Kulawiak
    • Zbigniew Łubniewski
    2019 Full text ISPRS International Journal of Geo-Information

    The rapid increase in applications of Light Detection and Ranging (LiDAR) scanners, followed by the development of various methods that are dedicated for survey data processing, visualization, and dissemination constituted the need of new open standards for storage and online distribution of collected three-dimensional data. However, over a decade of research in the area has resulted in a number of incompatible solutions that offer their own ways of disseminating results of LiDAR surveys (be it point clouds or reconstructed three-dimensional (3D) models) over the web. The article presents a unified system for remote processing, storage, visualization, and dissemination of 3D LiDAR survey data, including 3D model reconstruction. It is built with the use of open source technologies and employs open standards, such as 3D Tiles, LASer (LAS), and Object (OBJ) for data distribution. The system has been deployed for automatic organization, processing, and dissemination of LiDAR surveys that were performed in the city of Gdansk. The performance of the system has been measured using a selection of LiDAR datasets of various sizes. The system has shown to considerably simplify the process of data organization and integration, while also delivering tools for easy discovery, inspection, and acquisition of desired datasets.

  • Intelligent Autonomous Robot Supporting Small Pets in Domestic Environment
    • Artur Chrzanowski
    • Patryk Detko
    • Tomasz Stefański
    2019 Full text IFAC-PapersOnLine

    In this contribution, we present preliminary results of the student project aimed at the development of an intelligent autonomous robot supporting small pets in a domestic environment. The main task of this robot is to protect a freely moving small pets against accidental stepping on them by home residents. For this purpose, we have developed the mobile robot which follows a pet and makes an alarm signal when a human is approaching. A pet is recognized in images with the use of a convolutional neural network. Walls and obstacles are detected with the use of ultrasonic sensors. A control system of the robot is implemented with the use of the Jetson TX2 platform. Preliminary tests of the robot demonstrate not only usefulness of our solution but also further directions for its development.

  • Intelligent Autonomous Vehicles
    • Bogdan Wiszniewski
    • Zdzisław Kowalczuk
    • Mariusz Domżalski
    2019

    Advanced mobile vehicles and robots have long been one of the main issues in engineering. They have various applications in emergency, lifeguarding and entertainment as well as in various industrial, civil and military systems. Among them, you can distinguish robots that can move in an open environment or operate only in predetermined confined spaces. Open world robots are very demanding because they have to map their environment, adapt to changes and make their own decisions. In addition, current trends in robotics point to different social aspects and the importance of robot friendliness for humans.

  • Intelligent monitoring the vertical dynamics of wheeled inspection vehicles
    • Janusz Kozłowski
    • Zdzisław Kowalczuk
    2019 Full text IFAC-PapersOnLine

    The problem of intelligent monitoring of the vertical dynamics of wheeled inspection vehicles is addressed. With the independent MacPherson suspension system installed, the basic analysis focuses on the evaluation of the parameters of the so-called quarter car model. To identify a physically motivated continuous description, in practice, dedicated integral-horizontal filters are used. The obtained discrete model, which retains the original parameters, is effectively identified using the classic least squares procedure. Using the method of identification in the sense of the least sum of absolute values, the results of such an assessment become insensitive to sporadic outliers in the sampled data. However, the early signs of possible mechanical defects of the suspension can be seen using the forgetting mechanism. This helps to identify failures that can be recognized by changes in system parameters. Ultimately, the quality of the intelligent vehicle suspension monitoring developed is verified by means of numerical simulations. The problem of intelligent monitoring of the vertical dynamics of wheeled inspection vehicles is addressed. With the independent MacPherson suspension system installed, the basic analysis focuses on the evaluation of the parameters of the so-called quarter car model. To identify a physically motivated continuous description, in practice, dedicated integral-horizontal filters are used. The obtained discrete model, which retains the original parameters, is effectively identified using the classic least squares procedure. Using the method of identification in the sense of the least sum of absolute values, the results of such an assessment become insensitive to sporadic outliers in the sampled data. However, the early signs of possible mechanical defects of the suspension can be seen using the forgetting mechanism. This helps to identify failures that can be recognized by changes in system parameters. Ultimately, the quality of the intelligent vehicle suspension monitoring developed is verified by means of numerical simulations

  • Interactions of N-alkyl-N-methylmorpholinium based ionic liquids with acetonitrile studied by density and velocity of sound measurements and molecular dynamics simulations
    • Łukasz Marcinkowski
    • Maciej Śmiechowski
    • Emil Szepiński
    • Adam Kloskowski
    • Dorota Warmińska
    2019 JOURNAL OF MOLECULAR LIQUIDS

    Morpholinium-based ionic liquids (ILs) and their mixtures with polar co-solvents are an interesting class of emerging electrolytes in electrochemistry that is relatively poorly studied. In this work, densities and sound velocities of four ILs, N-ethyl-N-methylmorpholinium tetrafluoroborate, N-butyl-N-methylmorpholinium tetrafluoroborate, N-octyl-N-methylmorpho-linium tetrafluoroborate and N-decyl-N-methylmorpholinium tetrafluoroborate were measured in acetonitrile (AN) at T = (298.15–328.15) K and at atmospheric pressure. These data were used to calculate the apparent molar volumes and the apparent molar compressibilities as a function of molality. Then, an extrapolation procedure based on Masson and Redlich–Meyer equations were applied to evaluate the values of the limiting apparent molar volume and the limiting apparent molar compressibility. The limiting apparent molar expansibility coefficients were obtained from the slopes of the apparent molar volume at infinite dilution versus temperature. Using molecular dynamics simulations the degree of association of ILs in AN was calculated. Moreover, limiting apparent molar volumes were estimated and compared with the experimental values. The results indicate that the most significant factor controlling the volumetric and acoustic properties of the studied ILs in AN is the size of cation of the ionic liquid. Moreover, AN interacts more strongly with N-alkyl-N-methylmorpholinium tetrafluoroborates than dimethylsulfoxide and N, N-dimethylformamide, not only by strong ion-dipole interactions, but also by packing effect.

  • Interactions of selected mono- and disaccharides with precipitated calcium carbonate particles
    • Natalia Czaplicka
    • Donata Konopacka-Łyskawa
    2019

    Calcium carbonate is a widespread compound in nature and it can be produced by living organisms in the biomineralization process. Calcite, aragonite and vaterite are anhydrous polymorphic forms of calcium carbonate, wherein the calcite is the most thermodynamically stable. Vaterite is the metastable crystalline phase, which can be a precursor of calcite and aragonite, because it can easily transformed by dissolution and re crystallization into more stable forms. Synthetic CaCO3 obtained in the precipitation process is used as an additive in many products. There are two main methods for the production of precipitated calcium carbonate (PCC) on the industrial scale, i.e. precipitation in the gas liquid system and in the liquid liquid system. Diverse PCC applications require the use of well defined particles which are characterized by the polymorph composition, the particle morphology and the crystal size distribution. The concentration of reagents, temperature, pH, duration of the reaction and the presence of inorganic and organic additives play an important role during the calcium carbonate formation and influence on the product characteristics. The effect of glucose, fructose, sucrose and trehalose on the precipitation of CaCO3 in the gas liquid system has been investigated and it has been shown that the addition of saccharides into the reaction mixture can influence the polymorph composition of produced precipitates. Saccharides are characterized by different pKa values. The lower the pKa of the saccharide, the lower the initial pH of the aqueous solution. As a consequence, it leads to a longer initial time of reaction. The presence of saccharides in the solution increases the rate of the CO2 absorption. In addition, mono- and disaccharides are able to stabilize the pre-nucleation clusters of CaCO3, i.e. prevent their aggregation and coalescence. In this work, the interaction of selected saccharides has been studied using the NP-HPLC technique. As a stationary phase vaterite and rhombohedral calcite were used, while DMSO was an eluent. Solutions of saccharides in DMSO were samples injected to the tested columns. Among the analyzed disaccharides, trehalose is characterized by the smallest capacity factor for both calcium carbonate polymorphs, thus, it exhibits the weakest adsorptive interactions. Comparing monosaccharides, fructose interacts stronger with vaterite, while higher adsorptive interactions with calcite has been observed for glucose.

  • Interactions of telomeric proteins with nucleic acids: sequence recognition on intact and oxidatively damaged telomeres
    • Miłosz Wieczór
    2019 Full text

    Telomeres are complex nucleoprotein assemblies that play a vital role in the maintenance of functional ends of linear chromosomes. Telomeric DNA, composed of tandem repeats of the 5'-TTAGGG-3' motif, solves the so-called end replication problem: as chromosomes shorten with each cell division, no information is lost, and the telomere can be re-extended. In the cell, many protein factors regulate telomere length, nuclear positioning and conformation in response to cell cycle progression and the cell's proliferative status. Several proteins bind directly to single- or double-stranded telomeric DNA to assemble the main shelterin complex or play accessory roles. However, these interactions will be perturbed when the easily oxidized telomeric DNA is exposed to oxidative stress. In my doctoral work, I used Molecular Dynamics approaches to study the dynamics of protein-DNA complex formation at telomeres on the atomistic level, arriving at the most comprehensive thermodynamic, kinetic and mechanistic description of this process to date, including the first observation of spontaneous complex formation. I then investigated the impact of oxidative lesions on telomeric proteins, showing how base modifications disrupt sequence recognition on telomeric DNA. Finally, I used quantum chemical simulations to assess the feasibility of covalent protein-DNA cross-link formation on telomeres.

  • Interdisciplinary Design Teams in Poland - Architecture as a Tool for Preventing Hospital-Acquired Infections
    • Rafał Janowicz
    2019 Advances in Intelligent Systems and Computing

    Hospital-acquired infections pose a problem, which directly affects the safe usage of healthcare facilities. On a global scale, the level of hospital-acquired infections (HAI) is estimated to affect 5–15% of those hospitalised. The World Health Organization (WHO) estimates that, on an annual basis, procedures preventing hospital-acquired infections consume 80 billion dollars [1]. In this context, it becomes important to create conditions, which will significantly reduce the occurrence of hospital-acquired infections. Preliminary research in this field has shown that a correctly functioning system reduces the risk of the occurrence of hospital-acquired infections by anywhere from 55% to as much as 70% [2]. Architectural solutions affect sanitary and hygienic safety, as well as epidemiological safety, by appropriately shaping spatial parameters. The article is set to show the relations between architectural actions and epidemiological safety, as well as presenting the need for an on-going assessment of architectural solutions by interdisciplinary teams of specialists.

  • INTERDYSCYPLINARNOŚĆ W EDUKACJI STUDENTÓW ARCHITEKTURY. NA PRZYKŁADZIE BADANIA ZJAWISK WIATROWYCH W ŚRODOWISKU ZABUDOWANYM
    • Katarzyna Zielonko-Jung
    2019

    Celem artykułu jest prezentacja możliwości włączenia badań w zakresie aerodynamiki w proces kształcenia studentów wydziałów architektury. Opisano metodę pracy ze studentami uwzględniającą badania eksperymentalne w tunelu aerodynamicznym. Pozwala ona na rozpoznanie charakteru badanych zjawisk oraz na szersze spojrzenie na interdyscyplinarność w projektowaniu architektonicznym.

  • Inter-governmental Collaborative Networks for Digital Government Innovation Transfer -Structure, Membership, Operation
    • Magdalena Ciesielska
    • Tomasz Janowski
    2019 Full text

    Digital government refers to the transformation of government organizations and their relationships with citizens, business and each other through digital technology. It entails digital innovation in processes, services, organizations, policies, etc. which are increasingly developed and tested in one country and transferred, after adaptation, to other countries. The process of innovation transfer and the underlying information and knowledge sharing increasing take place through networks. The aim of this study is to identify various forms of such networks, their structures, membership criteria and modes of operation. The study relies on the analysis of literature on innovation transfer, collaborative networks and inter-governmental collaboration, and a survey of existing inter-governmental networks for digital government innovation transfer. The key finding is that such networks are a growing form of international collaboration and an instrument in global economy.

  • INTERNATIONALIZATION OF ENTERPRISES IN KAZAKHSTAN AS AN EXAMPLE OF INTERNATIONALIZATION PATTERNS IN THE AREA OF THE EURASIAN ECONOMIC UNION.
    • Inna Suchkova
    2019

    The article aims to show the specificity of the internationalization of Kazakh enterprises, in particular, the pace, scope, intensity, and forms of their internationalization in the Eurasian Economic Union (EEU). The EEU is a relatively young grouping that was established in 2015 by the Republic of Armenia, the Republic of Belarus, the Republic of Kazakhstan, the Kyrgyz Republic and the Russian Federation. EEU creators try to give the Eurasian integration process a different direction in contrast to the structures that were created in the post-Soviet space, namely, they want use experience form European Union integration. In this paper is shown the most important effects of international economic integration, and in particular the functioning of the Eurasian Economic Union (EEU) and characterizes the economy of Kazakhstan. Furthermore, the research conducted on exporters operating on the territory of the Republic of Kazakhstan, were shown. The research sample is 108 companies including 32 small & micro (<100 employees), 33 medium (101-250 employees) and large (>250 employees), resulting in median transnationalization index at 13.3. This shows still poor internationalization, however it is growing year to year.

  • Internationalization patterns of Polish family high-tech firms
    • Nelly Daszkiewicz
    2019 Full text Entrepreneurial Business and Economics Review

    The objective of the article is to explore internationalisation patterns of family high-tech firms, especially their internationalisation motives, intensity, speed, and entry modes. The empirical part adopts a quantitative approach. The results of the survey are presented on the sample of 263 high-tech production firms from Poland, including 101 family firms. The survey was conducted in all 16 Polish regions. The calculations from obtained survey results were made using Statistica PL 10.

  • Interpretable Deep Learning Model for the Detection and Reconstruction of Dysarthric Speech
    • Daniel Korzekwa
    • Roberto Barra-Chicote
    • Bożena Kostek
    • Thomas Drugman
    • Mateusz Łajszczak
    2019 Full text

    We present a novel deep learning model for the detection and reconstruction of dysarthric speech. We train the model with a multi-task learning technique to jointly solve dysarthria detection and speech reconstruction tasks. The model key feature is a low-dimensional latent space that is meant to encode the properties of dysarthric speech. It is commonly believed that neural networks are black boxes that solve problems but do not provide interpretable outputs. On the contrary, we show that this latent space successfully encodes interpretable characteristics of dysarthria, is effective at detecting dysarthria, and that manipulation of the latent space allows the model to reconstruct healthy speech from dysarthric speech. This work can help patients and speech pathologists to improve their understanding of the condition, lead to more accurate diagnoses and aid in reconstructing healthy speech for afflicted patients.

  • Introduction to MIP synthesis, characteristics and analytical application
    • Mariusz Marć
    • Piotr Paweł Wieczorek
    2019

    One of the trends in analytical chemistry is associated with designing and developing new types of sample preparation techniques, which might significantly increase the efficiency and selectivity of the analytes isolation or/and preconcentration process. One of the most widely employed solutions are selective sorption materials, defined as molecularly imprinted polymers (MIPs), as well as the sorbents with the molecular fingerprint. Due to their simple preparation protocol, mechanical, thermal and chemical stability and selectivity, MIPs have found application as a stationary phase in separation techniques such as liquid chromatography or capillary electrophoresis, in electrochemical sensors or as a specific sorption medium in solid phase extraction (SPE) technique. The preparation of a new type of polymer material is based on a specific template molecule using selected polymerization technique and characterization of the morphological and physicochemical properties of the obtained MIP. At the end, the studies which concern the suitability and usability of the obtained MIP material under real conditions, i.e. in the analysis of environmental samples (selectivity and efficiency of the isolation and/or preconcentration of analytes from environmental samples characterized by the complex matrix) should be performed. The following chapter contains the basic information about the MIP preparation protocols and potential fields of application of these selective sorption materials in analytical and environmental chemistry.

  • Inverse and forward surrogate models for expedited design optimization of unequal-power-split patch couplers
    • Sławomir Kozieł
    • Adrian Bekasiewicz
    2019 Full text Metrology and Measurement Systems

    In the paper, a procedure for precise and expedited design optimization of unequal power split patchcouplers is proposed. Our methodology aims at identifying the coupler dimensions that correspond to thecircuit operating at the requested frequency and featuring a required power split. At the same time, thedesign process is supposed to be computationally efficient. The proposed methodology involves two typesof auxiliary models (surrogates): an inverse one, constructed from a set of reference designs optimized forparticular power split values, and a forward one which represents the circuit S-parameter gradients as afunction of the power split ratio. The inverse model directly yields the values of geometry parameters ofthe coupler for any required power split, whereas the forward model is used for a post-scaling correction ofthe circuit characteristics. For the sake of illustration, a 10-GHz circular sector patch coupler is considered.The power split ratio of the structure is re-designed within a wide range of

  • Inverse heat transfer problem solution of sounding rocket using moving window optimization
    • Adam Dąbrowski
    • Leszek Dąbrowski
    2019 Full text PLOS ONE

    An Inverse Heat Transfer Problem is solved for a sounding rocket module given its geometry and measured temperature profile. The solution is obtained via moving window optimization, a technique for solving inverse dynamics. An analysis is performed to modify the method to avoid oscillatory behavior of the resulting heat flux profile. The method parameters are tuned in relation to characteristic phases of the flight. Results are presented and correlated with measured flight data. Conclusions are drawn for better experiments for measuring heat flux on a sounding rocket skin.

  • Investigation of optical properties of Infitec and Active Stereo stereoscopic techniques for CAVE-type virtual reality systems
    • Adam Mazikowski
    2019 Full text Metrology and Measurement Systems

    In recent years, many scientific and industrial centres in the world developed virtual reality systems or laboratories. At present, among the most advanced virtual reality systems are CAVE-type (Cave Automatic Virtual Environment) installations. Such systems usually consist of four, five, or six projection screens arranged in the form of a closed or hemi-closed space. The basic task of such systems is to ensure the effect of user “immersion” in the surrounding environment. The effect of user “immersion” into virtual reality in such systems is largely dependent on optical properties of the system, especially on quality of projection of three-dimensional images. In this paper, techniques of projection of three-dimensional (3D) images in CAVE-type virtual reality systems are analysed. The requirements of these techniques for such virtual reality systems are outlined. Based on the results of measurements performed in a unique CAVE-type virtual reality laboratory equipped with two different 3D projection techniques, named Immersive 3D Visualization Lab (I3DVL), that was recently opened at the Gdańsk University of Technology, the stereoscopic parameters and colour gamut of Infitec and Active Stereo stereoscopic projection techniques are examined and discussed. The obtained results enable to estimate the projection system quality for application in CAVE-type virtual reality installations.

  • Investigation of the Combustion Processes in the Gas Turbine Module of an FPSO Operating on Associated Gas Conversion Products
    • Oleksandr Cherednichenko
    • Serhiy Serbin
    • Marek Dzida
    2019 Full text Polish Maritime Research

    In this paper, we consider the issue of thermo-chemical heat recovery of waste heat from gas turbine engines for the steam conversion of associated gas for offshore vessels. Current trends in the development of offshore infrastructure are identified, and the composition of power plants for mobile offshore drilling units and FPSO vessels is analyzed. We present the results of a comparison of power-to-volume ratio, power-to-weight ratio and efficiency for diesel and gas turbine power modules of various capacities. Mathematical modeling methods are used to analyze the parameters of an alternative gas turbine unit based on steam conversion of the associated gas, and the estimated efficiency of the energy module is shown to be 50%. In the modeling of the burning processes, the UGT 25000 serial low emission combustor is considered, and a detailed analysis of the processes in the combustor is presented, based on the application of a 35-reaction chemical mechanism. We confirm the possibility of efficient combustion of associated gas steam conversion products with different compositions, and establish that stable operation of the gas turbine combustor is possible when using fuels with low calorific values in the range 7–8 MJ/kg. It is found that the emissions of NOx and CO during operation of a gas turbine engine on the associated gas conversion products are within acceptable limits.

  • Investigation of the temperature modulation parameters on semiconductor gas sensor response
    • Łukasz Woźniak
    • Paweł Kalinowski
    • Grzegorz Jasiński
    • Piotr Jasiński
    2019

    In this work we present the results of the investigation of the sensing properties of semiconductor gas sensors with a sinusoidally modulated temperature in the presence of synthetic air (SA) and three volatile air pollutants, i.e. NH3, NO2 and SO2. The measurements were performed for different average sensor heater temperatures and the amplitude of the modulation signal. In addition, the extraction of features from the sensor response using FFT analysis was performed. The results were compared with the results obtained by approach in which the sensors were supplied with a constant value of the heater voltage. The significance of the amplitudes of higher harmonics in the FFT signal was examined in relation to the parameters of modulating signal of the sensor. The goal of this study is to investigate the performance of sensor under different ranges of the working temperature.

  • Investigation of the thermal effects in water-lubricated journal bearings with axial grooves
    • Michał Wodtke
    • Wojciech Litwin
    2019

    Water-lubricated hydrodynamic journal bearings are frequently applied as stern tube bearings due to their advantages over other bearing types. They are environmentally friendly, can operate without sealings and in conditions of low friction losses. The most popular are bearings with open axial grooves, which require, for proper operation, forced axial flow of the lubricating water. Correctly designed and operated stern tube bearings can successfully work in the fluid friction regime. The dynamic viscosity of water is relatively low compared to oil. This results in smaller minimum film thickness and lower ability to carry the load for water-lubricated bearings in comparison to oil-lubricated bearings under similar operating conditions. This is considered as a disadvantage of this bearings type. However, at the same time, the lower water viscosity limits the temperature rise in the lubricating film and reduces friction losses. For this reason, it is common practice to not include thermal effects in the theoretical analysis of water lubricated bearings and to assume an isothermal flow in the gap. On the other hand, it is known from such bearings exploitation that they can fail due to overheating, resulting in melting of polymer material of the bush. Experimental tests of water-lubricated bearings with polymeric bushes have shown that the gradual reduction of axial water flow often results in excessive temperature rise. However, this was not valid for all tested bearing materials. In this paper, an investigation of thermal effects accompanying operation of water-lubricated journal bearing is presented. For this purpose, numerical bearing model was developed using FSI (Fluid-Solid Interaction) simulation. It allowed to take into account complexity of the important phenomena for the hydrodynamic performance of the bearing, as for example: heat generation in the fluid film due to shearing, deformations of the bush or forced axial water flow. A water-lubricated bearing from theoretical investigation was also tested experimentally with the use of a full-scale test stand. Experimental investigations under limited axial water flow through the bearing revealed significant rise of the measured temperature of the bush. Measured amount of the heat generated in the bearing friction zone was much higher compared to calculated values. ture rise and enlarged heat generation.

  • Investigation of Thermoplastic Polyurethanes Synthesized via Two Different Prepolymers
    • Paulina Kasprzyk
    • Ewelina Sadowska
    • Janusz Datta
    2019 Full text JOURNAL OF POLYMERS AND THE ENVIRONMENT

    The man aim of this work was to investigate the effect of the molecular weight of polyols, mixture of prepolymers, and [NCO]/[OH] molar ratio used during the prepolymer chain extending step on the chemical structure, thermomechanical and mechanical properties, and thermal stability of thermoplastic poly(ether-urethane)s In this work thermoplastic poly(ether-urethane)s were synthesized by using polyols with a various molecular weight, 4,4′-diphenylmethane diisocyanate and bio-based glycol. Materials were obtained by a two-step method. The tests were carried out for polyurethanes obtained from a mixture of prepolymers and for reference samples. In the case of materials obtained with using mixture of prepolymers, the ratio of both prepolymers was determined on 50/50 weight percent. Soft segments of materials prepared with using mixture consist of two different polyols. The chemical structure was analyzed using FTIR spectroscopy. The Gaussian deconvolution technique was used to study the hydrogen bonding as well as to decompose carbonyl region of three peaks in various TPUs. The thermal degradation behavior was investigated by using thermogravimetric analysis at heating rates of 10 °C/min. It was confirmed that the mixture of prepolymers has an effect of the degree of phase separation, thermal stability and selected properties of synthesized thermoplastic poly(ether-urethane)s.

  • Investigation of Weigh-in-Motion Measurement Accuracy on the Basis of Steering Axle Load Spectra
    • Dawid Ryś
    2019 Full text SENSORS

    Weigh-in-motion systems are installed in pavements or on bridges to identify and reduce the number of overloaded vehicles and minimise their adverse eect on road infrastructure. Moreover, the collected trac data are used to obtain axle load characteristics, which are very useful in road infrastructure design. Practical application of data from weigh-in-motion has become more common recently, which calls for adequate attention to data quality. This issue is addressed in the presented paper. The aim of the article is to investigate the accuracy of 77 operative weigh-in-motion stations by analysing steering axle load spectra. The proposed methodology and analysis enabled the identification of scale and source of errors that occur in measurements delivered from weigh-in-motion systems. For this purpose, selected factors were investigated, including the type of axle load sensor, air temperature and vehicle speed. The results of the analysis indicated the obvious eect of the axle load sensor type on the measurement results. It was noted that systematic error increases during winter, causing underestimation of axle loads by 5% to 10% for quartz piezoelectric and bending beam load sensors, respectively. A deterioration of system accuracy is also visible when vehicle speed decreases to 30 km/h. For 25% to 35% of cases, depending on the type of sensor, random error increases for lower speeds, while it remains at a constant level at higher speeds. The analysis also delivered a standard steering axle load distribution, which can have practical meaning in the improvement of weigh-in-motion accuracy and trac data quality.

  • Investigation on Mode I Fracture Behavior of Hybrid Fiber-Reinforced Geopolymer Composites
    • Neha P. Asrani
    • G. Murali
    • Hakim Abdelgader
    • K. Parthiban
    • M. K. Haridharan
    • K. Karthikeyan
    2019 Full text ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING

    Recent reports in the literature have shown that fber-reinforced geopolymer composites (FRGC) made with monofbers exhibit a signifcant enhancement in fracture energy. However, many aspects of the fracture performance of hybrid fberreinforced geopolymer composites (HFRGC) remain largely unexploited, and these are predominant for the structures. For the frst time, the mode I fracture energy of HFRGC is investigated. The mode I behavior was assessed using pre-notched beams in accordance with the RILEM three-point bending test. Five diferent HFRGC mixtures were prepared using three fber types: steel, polypropylene and glass (SF, PF and GF). The parameters of the pre-notched beam in fexure tested in this study were the frst crack and peak load, crack mouth opening displacement at the frst crack load and peak load, equivalent tensile strength, post-peak slope, reinforcing index, residual tensile strength and fracture energy. The results reveal that there is a positive interaction amidst the fbers in geopolymer composites that leads to an enhancement in the mode I fracture energy compared to the reference specimen. This study probes the infuence of novel HFRGC while producing high-quality concrete, which can then be leveraged for sustainable infrastructure and various civil engineering works.

  • Investigations of size effect in concrete at aggregate level - experiments and calculations results using discrete element method
    • Jan Suchorzewski
    2019 Full text

    Size effect is a fundamental phenomenon in concrete. It is characterised by decreasing strength and increasing brittleness of concrete with increasing size. The thesis includes experimental and theoretical elements. The main goal of the thesis were investigations of a size effect at the aggregate level by taking fracture into account with the discrete element method (DEM) for various failure modes. Comprehensive experiments on a size effect were carried out for a tensile splitting test. In experiments, the micro-computed tomography (micro-CT) and digital image correlation (DIC) technique were used. DEM for concrete was calibrated with the aid of simple uniaxial tests of uniaxial compression and uniaxial tension. In numerical calculations with the real internal concrete structure, the distribution and evolution of inter-particle contacts, inter-particle forces, force chains, rotations, broken contacts and energies was analyzed (depending on the specimen size) for various failure mechanisms: quasi-brittle, brittle and very brittle (snap-back). Experimental results were directly compared with experiments. Good agreement was achieved. In addition, comprehensive size effect experiments on reinforced concrete beams under bending without and with stirrups were carried out that were scaled along the height or length.