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Gdańsk University of Technology

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  • Application of non-classical operational calculus to indicate hazards in numerical solutions of engineering problems
    • Eligiusz Mieloszyk
    • Mariusz Wyroślak
    2020 Full text Studia Geotechnica et Mechanica

    The article addresses the application of non- classical operational calculus to approximative solutions of engineering problems. The engineering-sound examples show that a continuous–discrete problem transformation from differential unequivocal problem to a differential wildcard problem, triggering a change in solution quality. A number of approximative methods are capable to alter both quantitative and qualitative solution effects.

  • Application of probabilistic tools to extend load test design of bridges prior to opening
    • Piotr Owerko
    • Karol Winkelmann
    • Jarosław Górski
    2020 Structure and Infrastructure Engineering

    Load tests of bridges are widely performed in a large number of countries. Deterministic comparison of measurement results to the theoretical, FEM (finite element method)-based outcomes with possible further calibration is mostly applied. Sometimes, the data collected in the tests are also used to calibrate the reliability factors of bridge structures or their components. This work proposes to complement the stage of the load test design with the use of probabilistic tools. This approach is intended to provide a reliable and trustworthy limit range of measured values (e.g. displacements) instead of restrictive single values, streamlining the performance of in-situ tests. The proposed procedure is supported by an arch bridge example with the following uncertainty sources: random imperfections of the arch girder, random stiffness of the deck and random total weight of the applied load trucks. The presented calculations refer to global structural stiffness assessment. Both point estimate method (PEM) and response surface method (RSM) are applied here. It has been shown that the proposed procedure effectively supplements the deterministic approach, thus the suggested extension of application of probabilistic tools to bridge load test design is innovative and justified.

  • Application of safirinium N-hydroxysuccinimide esters to derivatization of peptides for high-resolution mass spectrometry, tandem mass spectrometry, and fluorescent labeling of bacterial cells
    • Joanna Fedorowicz
    • Magdalena Wierzbicka
    • Marek Cebrat
    • Paulina Wiśniewska
    • Rafał Piątek
    • Beata Zalewska-Piątek
    • Zbigniew Szewczuk
    • Jarosław Sączewski
    2020 Full text INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    Mass spectrometry methods are commonly used in the identification of peptides and biomarkers. Due to a relatively low abundance of proteins in biological samples, there is a need for the development of novel derivatization methods that would improve MS detection limits. Hence, novel fluorescent N-hydroxysuccinimide esters of dihydro-[1,2,4]triazolo[4,3-a]pyridin-2-ium carboxylates (Safirinium P dyes) have been synthesized. The obtained compounds, which incorporate quaternary ammonium salt moieties, easily react with aliphatic amine groups of peptides, both in solution and on the solid support; thus, they can be applied for derivatization as ionization enhancers. Safirinium tagging experiments with ubiquitin hydrolysate revealed that the sequence coverage level was high (ca. 80%), and intensities of signals were enhanced up to 8-fold, which proves the applicability of the proposed tags in the bottom-up approach. The obtained results confirmed that the novel compounds enable the detection of trace amounts of peptides, and fixed positive charge within the tags results in high ionization efficiency. Moreover, Safirinium NHS esters have been utilized as imaging agents for fluorescent labeling and the microscopic visualization of living cells such as E. coli Top10 bacterial strain.

  • Application of Shape Memory Alloys in Pipeline Couplings for Shipbuilding
    • Leszek Matuszewski
    2020 Full text Polish Maritime Research

    The aim of the study is to analyse shape memory alloy (SMA) pipeline joints in limited space applications for all kinds of ships. Generally, the space available in various areas on ships is strictly limited and service works usually meet many obstacles. If we consider a pipeline, the flange joints always require a larger free space around the pipe than the pipe alone. A simultaneous problem can occur with the propeller shaft line coupling between bearings. SMA couplings require less space around the pipe and service should be easier, e.g., insulation fixing, painting and so on. SMA couplings last for a lifetime and there is no need for periodical seal replacement. Herein, some proposals among other unpublished data are discussed. There is a significant technological interest in the use of SMAs for applications not widely used yet. A wide variety of alloys present the shape memory effect and many generate an expressive restitution force considerable for commercial interests.

  • Application of sliding switching functions in backstepping based speed observer of induction machine
    • Marcin Morawiec
    • Arkadiusz Lewicki
    2020 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS

    The paper presents an analysis of the speed observer which is based on the backstepping and sliding mode approach. The speed observer structure is based on the extended mathematical model of an induction machine. The observer structure is based on the measured phase stator currents and transformed to ( αβ ) coordinate system. The stator voltage vector components are treated as known values. Additionally, such an observer structure is extended to the integrators. The observer stabilizing functions contain the appropriate sliding surfaces which result from Lyapunov function. The rotor angular speed is obtained from non-adaptive dependence. Stability analysis of the observer structure based on Lyapunov theory is presented in order to guarantee the estimation errors decay to zero.

  • Application of Stirling Engine Type Alpha Powered by the Recovery Energy on Vessels
    • Jacek Kropiwnicki
    2020 Full text Polish Maritime Research

    The Stirling engine is a device, in which thermal energy is transformed into mechanical without a contact between the heat carrier, and the working gas closed in the engine. Mentioned feature makes this type of engine very attractive for the use of the recovery energy, taken from other heat devices. One of the potential applications of Stirling engines is the use of thermal energy generated in the ship's engine room for producing electricity. The work presents the concept of the Stirling engine type alpha powered by the recovery energy. The model of Stirling engine developed in this work allows a quantitative assessment of the impact of the design features of the engine, primarily the heat exchange surfaces and the volume of control spaces, on the achieved efficiency and power of the engine. Using the iterative procedure, the Stirling engine simulation tests were carried out taking into account the variable structural features of the system. The influence of the size of the heater and the cooler, as well as, the effectiveness of the regenerator and the temperature of the heat source on the efficiency and power produced by the Stirling engine have been presented.

  • Application of surface active amino acid ionic liquids as phase-transfer catalyst
    • Emil Szepiński
    • Patrycja Smolarek
    • Maria Milewska
    • Justyna Łuczak
    2020 JOURNAL OF MOLECULAR LIQUIDS

    Five structurally related morpholinium derived ionic liquids containing N-acetyl-glycinate anion were synthesized and their thermal stability, surface properties and activity as phase transfer catalysts investigated. The thermal properties were studied by differential scanning calorimetry, while the adsorption at the air/water interface and micellization behavior was analyzed by surface tension measurements, conductometry and isothermal titration calorimetry. The catalytic activity was assessed in two model reactions that were N-alkylation of dibenzoazepine and C-alkylation reaction of fluorene derivatives. The effect of the chain length, thus surface activity of the newly synthetized ionic liquids on the yields of N- and C-alkylation reactions was discussed.

  • Application of the Anammox Process for Treatment of Liquid Phase Digestate
    • Joanna Majtacz
    • Dominika Grubba
    • Krzysztof Czerwionka
    2020 Full text Water

    The liquid phase of the digestate (LPD) contains a relatively high concentration of nitrogen, with total ammonium nitrogen being the dominant form of nitrogen, as well as other essential nutrients such as phosphorus and potassium. Consequently, it must be treated before it is released into the environment. However, there are no reports of co-purification of LPD in the anammox process in sequencing batch reactor with granular sludge, which is a novelty for the presented research. The main objective of this paper is to assess the possibility of nitrogen removal in the anammox process with LPD from biogas plants conducting the co-fermentation process along with the participation of agricultural products (cattle slurry). This publication presents the research results of the efficiency of the anammox process, accounting for the effect of dissolved organic matter. The conducted experiments revealed the potential of LPD purification, which co-ferments waste activated sludge and bovine slurry for the anammox process. In the reactor ammonium utilization rate (AUR) process with LPD addition increased from 2.3 mg N/(g VSS∙h) with 0.5% LPD addition to 8.5 mg N/(g VSS∙h) with 7.5% LPD addition. SAA in the reactor with LPD addition increased from 5.3 mg N/(g VSS∙h) with 0.5% LPD addition to 18.5 mg N/(g VSS∙h) with 4 and 5% LPD addition. With the addition of 7.5% LPD, SAA dropped to a value of 18.1 mg N/(g VSS∙h) in the LPD reactor.

  • Application of the Chimney Cap as a Method of Improving the Effectiveness of Natural Ventilation in Buildings
    • Romana Antczak-Jarząbska
    • Maciej Niedostatkiewicz
    2020 Full text Polish Maritime Research

    Adequately designed natural ventilation is the cheapest and easiest way to effectively remove indoor pollutants and keep the air inside a building fresh. A prediction of the performance and effectiveness of ventilation in order to determine the design of a ventilation system can provide real and long-term cost savings. The worst time in terms of the efficiency of natural ventilation is the spring-autumn transition period [7]. In order to improve the efficiency of natural ventilation, chimney caps are used, among others. They are designed to improve the chimney effect described in colloquial language as a chimney draft. The chimney effect is a physical phenomenon of the formation of a spontaneous flow of a warmer gas, e.g. air, from the bottom up in stem channels [12]. The article analyses the influence of the chimney cowl on the improvement of the chimney effect in an apartment of a multi-family building with natural ventilation. Long-term tests of the chimney draft were carried out for the case without and with a chimney cap. The paper presents the results of the performance (air change rate, ACH) of natural ventilation for a building with an inlet gap measured for the transitional season (between the heating and the summer season). The measurements were performed during a windy period.

  • APPLICATION OF THE GWR MODEL FOR PREDICTING THE ROAD FATALITIES RATE ON THE ROAD NETWORK IN THE NUTS 3 REGIONS IN EUROPE ON THE EXAMPLE OF KUYAVIAN- -POMERANIAN VOIVODESHIP
    • Joanna Wachnicka
    • Katarzyna Palikowska
    2020 Full text Journal of KONBiN

    The article presents the application of the GWR (Geographically Weighted Regression) model to the description of differences in the level of road traffic safety in individual counties on the example of the Kuyavian-Pomeranian Voivodeship. The GWR model developed for counties, taking into account the diversity of NUTS 3 regions, can be a helpful tool for traffic safety management in voivodships and lower administrative units, and such an approach has not yet been applied.

  • Application of the LifeRoSE method in funcionality evaluation of road safety equipment
    • Anna Gobis
    • Kazimierz Jamroz
    • Łukasz Jeliński
    2020 Full text Journal of KONBiN

    The article presents a mathematical model of the life cycle estimation method of road safety equipment. Then the model was adjusted to estimate the life cycle costs of the chosen horizontal road marking. Using the LCC method, the functionality of the horizontal marking was evaluated in terms of efficiency, durability and economic effectiveness. The article also presents the impact of selected factors on the life cycle costs of the horizontal road marking

  • Application of the Monte Carlo algorithm for solving volume integral equation in light scattering simulations
    • Maciej Kraszewski
    • Jerzy Pluciński
    2020 Full text OPTICA APPLICATA

    Various numerical methods were proposed for analysis of the light scattering phenomenon. Important group of these methods is based on solving the volume integral equation describing the light scattering process. The popular method from this group is the discrete dipole approximation (DDA). DDA uses various numerical algorithms to solve the discretized integral equation. In the recent years, the application of the Monte Carlo (MC) algorithm as one of them was proposed. In this research, we analyze application of the MC algorithm for two cases: the light scattering by large particles and by random conglomerates of small particles. We show that if proper preconditioning of the numerical problem is applied, the MC algorithm can solve the underlying systems of linear equations. We also show that the efficiency of the MC algorithm can be increased by reusing performed computations for various incident electromagnetic waves and the applicability of the MC algorithm depends on the particular use case. It is unlikely to be used in the case of light scattering by the large particles due to computational times inferior comparing with the other numerical methods but may become useful in the case of light scattering by the random conglomerates of small scattering particles.

  • Application of the neural networks for developing new parametrization of the Tersoff potential for carbon
    • Anthony Chukwuemeka Nwachukwu
    • Szymon Winczewski
    2020 Full text TASK Quarterly

    Penta-graphene (PG) is a 2D carbon allotrope composed of a layer of pentagons having sp2- and sp3-bonded carbon atoms. A study carried out in 2018 has shown that the parameterization of the Tersoff potential proposed in 2005 by Ehrhart and Able (T05 potential) performs better than other potentials available for carbon, being able to reproduce structural and mechanical properties of the PG. In this work, we tried to improve the T05 potential by searching for its parameters giving a better reproduction of the structural and mechanical properties of the PG known from the ab initio calculations. We did this using Molecular Statics (MS) simulations and Neural Network (NN). Our test set consisted of the following structural properties: the lattice parameter a; the interlayer spacing h; two lengths of C-C bonds, d1 and d2 respectively; two valence angles, 1 and 2, respectively. We also examined the mechanical properties by calculating three elastic constants, C11, C12 and C66, and two elastic moduli, the Young’s modulus and the Poisson’s ratio . We used MS technique to compute the structural and mechanical properties of PG at = 0 K. The Neural Network used is composed of 2 hidden layers, with 20 and 10 nodes for the first and second layer, respectively. We used an Adams optimizer for the NN optimization and the Mean Squared Error as the loss function. We obtained inputs (about 80 000 different sets of potential parameters) for the Molecular Statics simulation by using randomly generated numbers. The outputs from these simulations became the inputs to our Neural Network. The Molecular Statics simulations were done with LAMMPS while the Neural Network and other computations were done with Python, Pytorch, Numpy, Pandas, GNUPLOT and Bash scripts. We obtained a parameterization which has a slightly better accuracy (lower relative errors of the calculated structural and mechanical properties) than the original parameterization.

  • Applying artificial neural networks for modelling ship speed and fuel consumption
    • Wiesław Tarełko
    • Krzysztof Rudzki
    2020 Full text NEURAL COMPUTING & APPLICATIONS

    This paper deals with modelling ship speed and fuel consumption using artificial neural network (ANN) techniques. These tools allowed us to develop ANN models that can be used for predicting both the fuel consumption and the travel time to the destination for commanded outputs (the ship driveline shaft speed and the propeller pitch) selected by the ship operator. In these cases, due to variable environmental conditions, making decisions regarding setting the proper commanded outputs to is extraordinarily difficult. To support such decisions, we have developed a decision support system. Its main elements are the ANN models enabling ship fuel consumption and speed prediction. To collect data needed for building ANN models, sea trials were conducted. In this paper, the decision support system concept, input and variables of the ship driveline system models, and data acquisition methods are presented. Based on them, we developed appropriate ANN models. Subsequently, we performed a quality assessment of the collected data set, data normalization and division of the data set, selection of an ANN model architecture and assessment of their quality.

  • Applying case studies to teaching architectural investment
    • Michał Kwasek
    • Rafał Janowicz
    2020 Full text World Transactions on Engineering and Technology Education

    Case studies enable students to encounter practical issues during their education. Experiments conducted in class employing this method often feature simplified models of real-world situations. However, they still enable students to encounter actual problems, to which theoretical knowledge is applied. In architectural education, students carrying out semester projects usually rely on data provided by the teacher, without wondering where the data came from. The case study method described here was implemented by means of a graph and in accordance with the principles of turquoise teaching. It has been implemented and used for several years in classes, where architecture students are taught how to manage their company and how to organise the investment process. The teaching covers essential guidelines that determine how the architect-manager works. Discussed in this article are the advantages of the method, the impact of it on the effectiveness of education and its application.

  • Approximation of Fractional Order Dynamic Systems Using Elman, GRU and LSTM Neural Networks
    • Bartosz Puchalski
    • Tomasz Rutkowski
    2020 Full text

    In the paper, authors explore the possibility of using the recurrent neural networks (RNN) - Elman, GRU and LSTM - for an approximation of the solution of the fractional-orders differential equations. The RNN network parameters are estimated via optimisation with the second order L-BFGS algorithm. It is done based on data from four systems: simple first and second fractional order LTI systems, a system of fractional-order point kinetics and heat exchange in the nuclear reactor core and complex nonlinear system. The obtained result shows that the studied RNNs are very promising as approximators of the fractional-order systems. On the other hand, these approximations may be easily implemented in real digital control platforms.

  • Aptamer based tools for environmental and therapeutic monitoring: A review of developments, applications, future perspectives
    • Błażej Kudłak
    • Monika Wieczerzak
    2020 Full text CRITICAL REVIEWS IN ENVIRONMENTAL SCIENCE AND TECHNOLOGY

    Nucleic acids in the form of aptamers play a growing and significant role in the targeted and rapid analysis of environmental sample composition and medical analyses. In this paper, the review of both aptamers synthesis methods as well as application of these short chain oligonucleotides (with critical comments on their strong and weak features) are given. The first ones include: systematic evolution of ligands by exponential enrichment (SELEX), high throughput aptamer identification screen (HAPIscreen), and a non-equilibrium capillary electrophoresis of equilibrium mixture (NECEEM). Afterwards, manuscript describes variety of sensors and biotests utilizing aptamers as active part of its action starting from electrochemical aptasensors, through optical to piezo-electric ones. Described biotests present basic developments in enzymelinked apta-sorbent assays (ELASA) that can be performed with different variations (enzyme-linked aptamer assay (ELAA), enzyme-linked oligonucleotide assay (ELONA) and aptamerlinked immobilized sorbent assay (ALISA)). Next, the review presents advantages and drawbacks of recent aptameric developments in versatile laboratory applications, namely medical ones, as well as analytical and bioassays. Utilitarian development of aptasensors and aptamers would strongly benefit from an assembly of interdisciplinary teams containing chemists, physicists, biologists, medical doctors, and material and electronic scientists, to determine the most effective application methodologies.

  • Architektura pomników poświęconych ofiarom ataków terrorystycznych jako kontynuacja realizacji komemoratywnych kształtowanych w postpamięci
    • Agnieszka Gębczyńska-Janowicz
    • Anna Awtuch
    2020 Full text Politeja. Pismo Wydziału Studiów Międzynarodowych i Politycznych Uniwersytetu Jagiellońskiego

    architecture of Memorials Dedicated to the Victims of terrorist attacks as a continuation of commemorative Structures created within Post-memory Having the rich art of commemorating events of the Second World War as a key reference, this article will try to show how contemporary architectural interven- tions in public space make attempts to respond to the social need of dealing with traumatic events and formulating a new attitude towards threatened places. The point of reference for our reflections will be the events affecting contemporary city in the 21th century associated with terrorist attacks. In order to determine types of architectural narratives about traumatic events developed in urban space, some memorial places in Europe and the USA will be analysed (e.g. Atocha station in Madrid, 9/11 Memorial in New York, Oklahoma City Bombing Memorial). Referring to examples of memorials and monuments, we will look at contempo- rary tendencies in designing commemorative architecture and how architecture reflects and supports the social and individual process of trauma recovery.

  • Artificial Thermal Ageing of Polyester Reinforced and Polyvinyl Chloride Coated Technical Fabric
    • Paweł Kłosowski
    • Krzysztof Żerdzicki
    • Krzysztof Woźnica
    2020 Full text Jove-Journal of Visualized Experiments

    Architectural fabric AF9032 has been subjected to artificial thermal ageing to determine changes of the material parameters of the fabric. The proposed method is based on the accelerated ageing approach proposed by Arrhenius. 300 mm x 50 mm samples were cut in the warp and fill directions and placed in a thermal chamber at 80 °C for up to 12 weeks or at 90 °C for up to 6 weeks. Then after one week of conditioning at ambient temperature, the samples were uniaxially tensioned at a constant strain rate. Experimentally, the parameters were determined for the non-linear elastic (linear piecewise) and viscoplastic (Bodner–Partom) models. Changes in these parameters were studied with respect to the ageing temperature and ageing period. In both cases, the linear approximation function was successfully applied using the simplified methodology of Arrhenius. A correlation was obtained for the fill direction between experimental results and the results from the Arrhenius approach. For the warp direction, the extrapolation results exhibited some differences. Increasing and decreasing tendencies have been observed at both temperatures. The Arrhenius law was confirmed by the experimental results only for the fill direction. The proposed method makes it possible to predict real fabric behavior during long term exploitation, which is a critical issue in the design process

  • Assessing Industry 4.0 Features Using SWOT Analysis
    • Ahmad Reshad Bakhtari
    • Mohammad Waris
    • Bisma Mannan
    • Cesar Sanin
    • Edward Szczerbicki
    2020 Full text Communications in Computer and Information Science

    This paper assesses some features of industry 4.0 by using SWOT analysis that affects the adoption and implementation of industry 4.0. The paper identifies the strengths, weaknesses, opportunities, and threats related to industry 4.0. By the consideration of these four groups of factors, the industrial practitioners can understand how to implement industry 4.0. Moreover, industrial practitioners can use the strengths/opportunities offered by industry 4.0 to take strategic decisions to decrease the effect of the threats/weaknesses that come along with industry 4.0.

  • Assessment of Citizens’ Actions against Light Pollution with Guidelines for Future Initiatives
    • Karolina Zielińska-Dąbkowska
    • Kyra Xavia
    • Katarzyna Bobkowska
    2020 Full text Sustainability

    Due to the wide reach of media reports about scientific research and technological tools such as the world wide web (WWW), the Internet, and web browsers, citizens today have access to factual information about the negative impact of artificial light at night (ALAN) on their dark skies, and their health and well-being. This means they can now make educated decisions and take the necessary steps to help protect themselves and their communities from disruptive light pollution. Whilst this action is positive and welcomed, unfortunately, according to collected data, not all such initiatives have been successful. Although our understanding of this groundswell movement is deepening, further studies are required to complete a worldwide picture of the current situation. This paper therefore investigates the various actions taken by citizens, as well as the challenges, methods, and tools involved, regarding good practices initiated by grass roots activism on how to reduce existing and potential light pollution. The results of a comparative analysis of 262 international case studies (lawsuits and online petitions) reveal that, since the 1990s, there has been an increase in the number of legal cases related to light pollution due to the rise in public awareness, the availability of scientific knowledge via the Internet, and the ability to take accurate lighting measurements and perform lighting simulations. Also, in the last decade a new tool for digital participation in the form of online petitions has established a new movement of citizen action to mitigate the effects of light pollution. Based on this information, a seven-step framework involving recommendations for citizen action has been developed. It is expected that this new knowledge will benefit those citizens planning future efforts involving the development, implementation, and monitoring processes of outdoor lighting. Additionally, it might support the evolution of planning and policy approaches that are sustainable and necessary to improve the application and installation of ecologically/biologically responsible illumination for towns, cities, and natural habitats.

  • Assessment of Electronic Sensing Techniques for the Rapid Identification of Alveolar Echinococcosis through Exhaled Breath Analysis
    • Andrzej Kwiatkowski
    • Tomasz Chludziński
    • Tarik Saidi
    • Tesfalem Welearegay
    • Aylen Jaimes-Mogollón
    • Nezha El Bari
    • Sebastian Borys
    • Benachir Bouchikhi
    • Janusz Smulko
    • Radu Ionescu
    2020 Full text SENSORS

    Here we present a proof-of-concept study showing the potential of a chemical gas sensors system to identify the patients with alveolar echinococcosis disease through exhaled breath analysis. The sensors system employed comprised an array of three commercial gas sensors and a custom gas sensor based on WO3 nanowires doped with gold nanoparticles, optimized for the measurement of common breath volatile organic compounds. The measurement setup was designed for the concomitant measurement of both sensors DC resistance and AC fluctuations during breath samples exposure. Discriminant Function Analysis classification models were built with features extracted from sensors responses, and the discrimination of alveolar echinococcosis was estimated through bootstrap validation. The commercial sensor that detects gases such as alkane derivatives and ethanol, associated with lipid peroxidation and intestinal gut flora, provided the best classification (63.4% success rate, 66.3% sensitivity and 54.6% specificity) when sensors’ responses were individually analyzed, while the model built with the AC features extracted from the responses of the cross-reactive sensors array yielded 90.2% classification success rate, 93.6% sensitivity and 79.4% specificity. This result paves the way for the development of a noninvasive, easy to use, fast and inexpensive diagnostic test for alveolar echinococcosis diagnosis at an early stage, when curative treatment can be applied to the patients

  • ASSESSMENT OF FINANCIAL SECURITY OF AN ENTERPRISE ON THE BASIS OF BEHAVIORAL ECONOMICS
    • Oleksandr Melnychenko
    2020 Full text BULLETIN OF THE CHERKASY BOHDAN KHMELNYTSKY NATIONAL UNIVERSITY. ECONOMIC SCIENCES

    The article substantiates that the level of company’s financial security depends not so much on the indicators of its activity, but on its perception of decision-makers and other stakeholders. At the same time, this perception is formed due to the continuous participation of the stakeholder in operations, constant monitoring of financial indicators, the study of current approaches to enterprise management, changes in the environment, market conditions, etc. The role of economic analysis in assessing company’s financial security as a state is not in its complex study, but in the presented economic indicators, the processing of quantitative data on the company’s financial security. Instead, to speak of a comprehensive and thorough study of the level of financial security on the basis of economic analysis only would be incorrect and unreliable. Indices, indicators that are analyzed on the basis of financial or management reporting provide only a cursory view of the problem or even distort the overall picture, as they are taken at a particular point in time. For example, liquidity indicators change in certain groups of businesses and the country's economic or political environment can transform a liquid company with a solid stock of liquidity into absolutely illiquid in a few moments. However, considering the previous data of economic analysis without bearing in mind other aspects, it is possible to make fatal decisions for the company. Although, of course, such a scenario is impossible, since behind each enterprise there are people, whose decisions and experience depend on its further development, and practice shows that such people are not oriented solely to economic analysis data without context, to assess the situation in the economy of the country or the world in general. Their experience and perception of financial security are essencial in decision making. Thus, the paper argues that the method of expert assessment of company’s financial security is the most objective one, which, however, has disadvantages associated with cognitive limitations of people

  • Assessment of the Effective Variants Leading to Higher Efficiency for the Geothermal Doublet, Using Numerical Analysis‒Case Study from Poland (Szczecin Trough)
    • Anna Wachowicz-Pyzik
    • Anna Sowiżdżał
    • Leszek Pająk
    • Paweł Ziółkowski
    • Janusz Badur
    2020 Full text ENERGIES

    Numerical models of geothermal doublet allows us to reduce the high risk associated with the selection of the most eective location of a production well. Furthermore, modeling is a suitable tool to verify possible changes in operational geothermal parameters, which guarantees liveliness of the system. An appropriate selection of software as well as the methodology used to generate numerical models significantly aects the quality of the obtained results. In this paper, the authors discuss the influence of such parameters as grid density and distance between wells on the eciency of geothermal heating plant. The last stage of the analysis was connected with estimation of geothermal power potential for a hypothetical geothermal doublet. Numerical simulations were carried out using the TOUGH2 code, which applies the finite-dierence method. The research was conducted in the Szczecin Trough area (NW Poland), based on archival data from Choszczno IG-1 well. The results demonstrated that in the studied case of the Choszczno region, the changes in the distance of boreholes can have a visible influence on obtained results; however the grid density of the numerical model did not achieve a significant impact on it. The results show the significant importance of numerical modeling aimed at increasing the eciency of a potential geothermal heating plant.

  • Assessment of the Speed Management Impact on Road Traffic Safety on the Sections of Motorways and Expressways Using Simulation Methods
    • Jacek Oskarbski
    • Tomasz Kamiński
    • Kyandoghere Kyamakya,
    • Jean Chamberlain Chedjou,
    • Karol Żarski
    • Małgorzata Pędzierska
    2020 Full text SENSORS

    Methods used to evaluate the impact of Intelligent Transport System (ITS) services on road safety are usually based on expert assessments or statistical studies. However, commonly used methods are challenging to apply in the planning process of ITS services. This paper presents the methodology of research using surrogate safety measures calculated and calibrated with the use of simulation techniques and a driving simulator. This approach supports the choice of the type of ITS services that are beneficial for traffic efficiency and road safety. This paper presents results of research on the influence of selected scenarios of variable speed limits on the eciency and safety of traffic on the sections of motorways and expressways in various traffic conditions. The driving simulator was used to estimate the eciency of lane-keeping by the driver. The simulation traffic models were calibrated using driving simulator data and roadside sensor data. The traffic models made it possible to determine surrogate safety measures (number of conflicts and their severity) in selected scenarios of using ITS services. The presented studies confirmed the positive impact of Variable Speed Limits (VSLs) on the level of road safety and traffic efficiency. This paper also presents recommendations and plans for further research in this area.

  • Assessment of Trajectories of Non-bankrupt and Bankrupt Enterprises
    • Tomasz Korol
    2020 Full text European Research Studies Journal

    The aim of this study is to show how long-term trajectories of enterprises can be used to increase the forecasting horizon of bankruptcy prediction models. The author used seven popular forecasting models (two from Europe, two from Asia, two from North America and one from Latin America). These models (five multivariate discriminant analysis models and two logit models) were used to develop 17-year trajectories separately for non-bankrupt enterprises and those at risk of financial failure. Based on a sample of 200 enterprises, the author evaluated the differences between non-bankrupt and bankrupt firms in development during 17 years of activity. The long-term usability of the models was demonstrated. To date, these models have been used only to forecast bankruptcy risk in the short term (1–3 years’ prediction horizon). This paper demonstrates that these models can also serve to evaluate long-term growth and to identify the first symptoms of future bankruptcy risk many years before it actually occurs. It was proven and specified that long-term developmental differences exist between non-threatened and future insolvent companies. These studies proved that the process of going bankrupt is very long, perhaps even longer than the literature has previously demonstrated. This study is one of the first attempts in the literature globally to assess such long-term enterprise trajectories. Additionally by implementing a dynamic approach to the financial ratios in the risk-forecasting model let visualize the changes occurring in the company.

  • Assessment of Wide-Sense Stationarity of an Underwater Acoustic Channel Based on a Pseudo-Random Binary Sequence Probe Signal
    • Iwona Kochańska
    2020 Full text Applied Sciences-Basel

    The performances of Underwater Acoustic Communication (UAC) systems are strongly related to the specific propagation conditions of the underwater channel. Designing the physical layer of a reliable data transmission system requires a knowledge of channel characteristics in terms of the specific parameters of the stochastic model. The Wide-Sense Stationary Uncorrelated Scattering (WSSUS) assumption simplifies the stochastic description of the channel, and thus the estimation of its transmission parameters. However, shallow underwater channels may not meet the WSSUS assumption. This paper proposes a method for testing the Wide-Sense Stationary (WSS) part of the WSSUS feature of a UAC channel on the basis of the complex envelope of a received probe Pseudo-Random Binary Sequence (PRBS) signal. Two correlation coefficients are calculated that can be interpreted, together, as a measure that determines whether the channel is WSS or not. A similar wide-sense stationarity assessment can be performed on the basis of the Time-Varying Impulse Response (TVIR) of a UAC channel. However, the method proposed in this paper requires fewer computational operations in the receiver of a UAC system. PRBS signal transmission tests were conducted in the UAC channel simulator and in real conditions during an inland water experiment. The correlation coefficient values obtained using the method based on the envelope of a probe signal and the method of analysing the TVIR estimates are compared. The results are similar, and thus, it is possible to assess if the UAC channel can be modelled as a WSS stochastic process without the need for TVIR estimation.

  • Association of Genes Related to Oxidative Stress with the Extent of Coronary Atherosclerosis
    • Milena Racis
    • Anna Stanisławska-Sachadyn
    • Wojciech Sobiczewski
    • Marcin Wirtwein
    • Michał Krzemiński
    • Natalia Krawczyńska
    • Janusz Limon
    • Andrzej Rynkiewicz
    • Marcin Gruchała
    2020 Full text Life

    Oxidative stress is believed to play a critical role in atherosclerosis initiation and progression. In line with this, in a group of 1099 subjects, we determined eight single nucleotide polymorphisms (SNPs) related to oxidative stress (PON1 c.575A>G, MPO c.463G>A, SOD2 c.47T>C, GCLM c.590C>T, NOS3 c.894G>T, NOS3 c.786T>C, CYBA c.214C>T, and CYBA c.932A>G) and assessed the extent of atherosclerosis in coronary arteries based on Gensini score. An increased risk of having a Gensini score in the higher half of the distribution was observed for the PON1 c.575G allele (odds ratio (OR) = 1.27, 95% confidence interval (CI): 1.004–1.617, p = 0.046). Next, the genetic risk score (GRS) for the additive eect of the total number of pro-oxidative alleles was assessed. We noted an increase in the risk of having a Gensini score above the median with the maximum number of risk alleles (OR = 2.47, 95% CI: 1.19–5.23, p = 0.014). A univariate Spearman’s test revealed significant correlation between the total number of pro-oxidant alleles (GRS) and the Gensini score ( = 0.068, p = 0.03). In conclusion, the PON1 c.575A>G variant and the high number of risk alleles (GRS) were independent risk factors for a high Gensini score. We suggest, however, that GRS might occur as a more valuable component in adding a predictive value to the genetic background of atherosclerosis.

  • Attempt to a Video-Transmission Capability in MV Mine Cable Network Using BPL-PLC Technology
    • Grzegorz Debita
    • Przemysław Falkowski-Gilski
    • Marcin Habrych
    • Bogdan Miedziński
    • Grzegorz Wiśniewski
    • Przemysław Jedlikowski
    • Bartosz Polnik
    2020

    This article presents and discusses the attempt to transmit video content using the BPL-PLC (Broadband over Power Line - Power Line Communication) technology. It includes simulation results of a specially developed digital transmitter and receiver, dedicated to a given predefined 6 kV mining power cable. The effect of two different transmission modes (2-7 MHz and 3-7.5 MHz) and two types of coupling (capacitive-inductive and induction-inductive), on the quality of bi-directional transmission, was also examined. The quality assessment of transmitted content, including both QoS (Quality of Service) and QoE (Quality of Experience) approaches, was evaluated on a set of samples processed in different resolution, namely: 480x270, 768x432, and 1280x720. Based on this, conclusions have been formulated, regarding the expected efficiency, as well as guidelines for further video transmission tests, including real-time mining conditions.

  • Atypical application of the parametric method for track infrastructure inventory
    • Krzysztof Czaplewski
    • Cezary Specht
    • Władysław Koc
    • Andrzej Wilk
    • Krzysztof Karwowski
    • Paweł Dąbrowski
    • Mariusz Specht
    • Piotr Chrostowski
    • Jacek Szmagliński
    2020 Full text Zeszyty Naukowe Akademii Morskiej w Szczecinie

    For many years, satellite systems have seen widespread use in a variety of technical applications, as well as in operations related to setting-out and the exploitation of track infrastructure. Their main applications include an inventory of the trackage course and detecting changes in its position. In both of these tasks, the most important element that determines the quality of an analyses is the high accuracy of the determinations being carried out. Satellite surveying techniques are not always sufficiently accurate, and in such cases, it is necessary to employ other land surveying methods to process surveying data. This article presents the authors’ considerations with regards to the possibility of applying one of the most common land surveying adjustment methods, the parametric method, to operations related to an inventory of tram infrastructure in Gdańsk. The results are based on surveys carried out during a surveying campaign in the autumn of 2018. The considerations presented in the article concern a small part of the research conducted under project No. POIR.04.01.01-00-0017/17 entitled “Development of an innovative method for determining the precise trajectory of a railborne vehicle” which is being implemented by a consortium of Gdansk University of Technology and Gdynia Maritime University.

  • Audio Feature Analysis for Precise Vocalic Segments Classification in English
    • Szymon Zaporowski
    • Andrzej Czyżewski
    2020

    An approach to identifying the most meaningful Mel-Frequency Cepstral Coefficients representing selected allophones and vocalic segments for their classification is presented in the paper. For this purpose, experiments were carried out using algorithms such as Principal Component Analysis, Feature Importance, and Recursive Parameter Elimination. The data used were recordings made within the ALOFON corpus containing audio signal recorded employing 7 speakers who spoke English at the native or near-native speaker level withing a Standard Southern British English variety accent. The recordings were analyzed by specialists from the field of phonology in order to extract vocalic segments and selected allophones. Then parameterization was made using Mel Frequency Cepstral Coefficients, Delta MFCC, and Delta Delta MFCC. In the next stage, feature vectors were passed to the input of individual algorithms utilized to reduce the size of the vector by previously mentioned algorithms. The vectors prepared in this way have been used for classifying allophones and vocalic segments employing simple Artificial Neural Network (ANN) and Support Vector Machine (SVM). The classification results using both classifiers and methods applied for reducing the number of parameters were presented. The results of the reduction are also shown explicitly, by indicating parameters proven to be significant and those rejected by particular algorithms. Factors influencing the obtained results were discussed. Difficulties associated with obtaining the data set, its labeling, and research on allophones were also analyzed.

  • AutoCAD: Examination of Factors Influencing User Adoption
    • Anna Baj-Rogowska
    2020 Full text Engineering Management in Production and Services

    The primary purpose of the research is to examine and validate determinants of user intention to use AutoCAD software, utilising the constructs from prior studies in a more integrated model. The paper proposes a revised Technology Acceptance Model (TAM) for measuring the adoption of AutoCAD. In the study, a latent construct PPA (perceived physical accessibility) was added to the proposed research model as a new determinant of AutoCAD adoption. An online survey of AutoCAD users was conducted to collect data. This data was empirically used to test the proposed research model. The Structural Equation Modelling (SEM) technique was used to evaluate the causal model, and the confirmatory factor analysis was performed to examine the reliability and validity of the measurement model. The study results show that user behavioural intention to use AutoCAD is significantly affected by three determinants: perceived usefulness, perceived ease of use and perceived physical accessibility of the software. This finding contributes to an expanded understanding of the factors that promote acceptance of AutoCAD software. Moreover, the main contribution of this study is to verify the impact of the added PPA variable on the behavioural intention to use and the actual use of AutoCAD, and also to create measurement scales for this new latent variable in TAM.

  • Autogenous Fiber Laser Welding of 316L Austenitic and 2304 Lean Duplex Stainless Steels
    • Michał Landowski
    • Aleksandra Świerczyńska
    • Grzegorz Rogalski
    • Dariusz Fydrych
    2020 Full text Materials

    This study presents results of experimental tests on quality of dissimilar welded joints between 316L austenitic and 2304 lean duplex stainless steels, welded without ceramic backing. Fiber laser welded butt joints at a thickness of 8 mm were subjected to non‐destructive testing (visual and penetrant), destructive testing (static tensile test, bending test, and microhardness measurements) and structure observations (macro‐ and microscopic examinations, SEM, element distribution characteristics, and ferrite content measurements). Non‐destructive tests and metallographic examinations showed that the welded joints meet the acceptance criteria for B level in accordance with EN ISO 13919–1 standard. Also the results of the destructive tests confirmed the high quality of the joints: specimens were fractured in base material with lower strength—316L austenitic stainless steel and a 180° bending angle was obtained confirming the high plasticity of the joints. Microscopic examination, SEM and EDS analysis showed the distribution of alloying elements in joints. The microhardness of the autogenous weld metal was higher by about 20 HV0.2 than that of the lean duplex steel. Ferrite content in the root was about 37% higher than in the face of the weld. The Schaeffler phase diagram was used to predict the phase composition of the welded joints and sufficient compliance with the magnetic method was found. The presented procedure can be used for welding of 316L–2304 stainless steels dissimilar welded joints of 8 mm thickness without ceramic backing.

  • Automated Classifier Development Process for Recognizing Book Pages from Video Frames
    • Adam Brzeski
    • Jan Cychnerski
    • Karol Draszawka
    • Krystyna Dziubich
    • Tomasz Dziubich
    • Waldemar Korłub
    • Paweł Rościszewski
    2020 Communications in Computer and Information Science

    One of the latest developments made by publishing companies is introducing mixed and augmented reality to their printed media (e.g. to produce augmented books). An important computer vision problem that they are facing is classification of book pages from video frames. The problem is non-trivial, especially considering that typical training data is limited to only one digital original per book page, while the trained classifier should be suitable for real-time utilization on mobile devices, where camera can be exposed to highly diverse conditions and computing resources are limited. In this paper we address this problem by proposing an automated classifier development process that allows training classification models that run real-time, with high usability, on low-end mobile devices and achieve average accuracy of 88.95% on our in-house developed test set consisting of over 20 000 frames from real videos of 5 books for children. At the same time, deployment tests reveal that the classifier development process time is reduced approximately 16-fold.

  • Automatic Marking of Allophone Boundaries in Isolated English spoken Words
    • Janusz Rafałko
    • Andrzej Czyżewski
    2020 Full text

    The work presents a method that allows delimiting the borders of allophones in isolated English words. The described method is based on the DTW algorithm combining two signals, a reference signal and an analyzed one. As the reference signal, recordings from the MODALITY database were used, from which the words were extracted. This database was also used for tests, which were described. Test results show that the automatic determination of the allophone limits in English words is possible with good accuracy. Tests have been carried out to determine the error of particular allophones borders marking and to find out the cost of matching the given allophone to the reference one. Based on this cost, a coefficient has been introduced that allows for determining in percentage how much the automatically marked allophone is similar to the reference one. This coefficient can be used for an assessment of the correctness of the pronunciation of the allophone. The possibilities of further research and development of this method were also analyzed.

  • Automatic Threat Detection for Historic Buildings in Dark Places Based on the Modified OptD Method
    • Wioleta Błaszczak-bąk
    • Czesław Suchocki
    • Joanna Janicka
    • Andrzej Dumalski
    • Robert Duchnowski
    • Anna Sobieraj-Żłobińska
    2020 Full text ISPRS International Journal of Geo-Information

    Historic buildings, due to their architectural, cultural, and historical value, are the subject of preservation and conservatory works. Such operations are preceded by an inventory of the object. One of the tools that can be applied for such purposes is Light Detection and Ranging (LiDAR). This technology provides information about the position, reflection, and intensity values of individual points; thus, it allows for the creation of a realistic visualization of the entire scanned object. Due to the fact that LiDAR allows one to ʹseeʹ and extract information about the structure of an object without the need for external lighting or daylight, it can be a reliable and very convenient tool for data analysis for improving safety and avoiding disasters. The main goal of this paper is to present an approach of automatic wall defect detection in unlit sites by means of a modified Optimum Dataset (OptD) method. In this study, the results of Terrestrial Laser Scanning (TLS) measurements conducted in two historic buildings in rooms without daylight are presented. One location was in the basement of the ruins of a medieval tower located in Dobre Miasto, Poland, and the second was in the basement of a century‐old building located at the University of Warmia and Mazury in Olsztyn, Poland. The measurements were performed by means of a Leica C‐10 scanner. The acquired dataset of x, y, z, and intensity was processed by the OptD method. The OptD operates in such a way that within the area of interest where surfaces are imperfect (e.g., due to cracks and cavities), more points are preserved, while at homogeneous surfaces (areas of low interest), more points are removed (redundant information). The OptD algorithm was additionally modified by introducing options to detect and segment defects on a scale from 0 to 3 (0—harmless, 1—to the inventory, 2—requiring repair, 3—dangerous). The survey results obtained proved the high effectiveness of the modified OptD method in the detection and segmentation of the wall defects. The values of area of changes were calculated. The obtained information about the size of the change can be used to estimate the costs of repair, renovation, and reconstruction.

  • Autonomous Ship Utility Model Parameter Estimation Utilising Extended Kalman Filter
    • Anna Witkowska
    • Krzysztof Armiński
    • Tomasz Zubowicz
    • Filip Ossowski
    • Roman Smierzchalski
    2020

    In this paper, a problem of autonomous ship utility model identification for control purposes is considered. In particular, the problem is formulated in terms of model parameter estimation (one-step-ahead prediction). This is a complex task due to lack of measurements of the parameter values, their time-variability and structural uncertainty introduced by the available models. In this work, authors consider and compare two utility models based on often utilised ship model structures with time-varying parameters identified recursively using the extended Kalman lter (EKF). The validation results have been obtained using simulation experiments in which the required information for the parameter estimation task had been generated using a cognitive model of B-481 ship. The results indicate the benefits and drawbacks, In terms of estimation accuracy and computational complexity, of using each of the investigated utility model structures.

  • Auto-tuning methodology for configuration and application parameters of hybrid CPU + GPU parallel systems based on expert knowledge
    • Paweł Czarnul
    • Paweł Rościszewski
    2020 Full text

    Auto-tuning of configuration and application param- eters allows to achieve significant performance gains in many contemporary compute-intensive applications. Feasible search spaces of parameters tend to become too big to allow for exhaustive search in the auto-tuning process. Expert knowledge about the utilized computing systems becomes useful to prune the search space and new methodologies are needed in the face of emerging heterogeneous computing architectures. In this paper we propose an auto-tuning methodology for hybrid CPU/GPU applications that takes into account previous execution experi- ences, along with an automated tool for iterative testing of chosen combinations of configuration, as well as application-related parameters. Experimental results, based on a parallel similarity search application executed on three different CPU+GPU parallel systems, show that the proposed methodology allows to achieve execution times worse by only up to 8% compared to a search algorithm that performs a full search over combinations of application parameters, while taking only up to 26% time of the latter.

  • Axial-Flux Permanent-Magnet Dual-Rotor Generator for a Counter-Rotating Wind Turbine
    • Filip Kutt
    • Krzysztof Blecharz
    • Dariusz Karkosiński
    2020 Full text ENERGIES

    Coaxial counter-rotating propellers have been widely applied in ships and helicopters for improving the propulsion efficiency and offsetting system reactive torques. Lately, the counter-rotating concept has been introduced into the wind turbine design. Distributed wind power generation systems often require a novel approach in generator design. In this paper, prototype development of axial-flux generator with a counter-rotating field and armature is presented. The design process was composed of three main steps: analytical calculation, FEM simulation and prototype experimental measurements. The key aspect in the prototype development was the mechanical construction of two rotating components of the generator. Sturdy construction was achieved using two points of contact between both rotors via the placement of the bearing between the inner and outer rotor. The experimental analysis of the prototype generator has been conducted in the laboratory at the dynamometer test stand equipped with a torque sensor. The general premise for the development of such a machine was an investigation into the possibility of developing a dual rotor wind turbine. The proposed solution had to meet certain criteria such as relatively simple construction of the generator and the direct coupling between the generator and the wind turbines. The simple construction and the lack of any gearbox would allow for such a system to be constructed relatively cheaply, which is a key aspect in further system development.

  • Badania bezczujnikowego układu napędowego z silnikiem pięciofazowym w normalnych i awaryjnych stanach pracy.
    • Filip Wilczyński
    • Marcin Morawiec
    • Krzysztof Blecharz
    • Andrzej Jąderko
    2020 Full text Przegląd Elektrotechniczny

    W artykule przedstawiono bezczujnikowe sterowanie polowo zorientowane dla pięciofazowego silnika indukcyjnego. Zaproponowany układ sterowania został przebadany pod kątem możliwej pracy w przypadku braku zasilania jednej oraz dwóch faz stojana silnika. Zaprezentowane wyniki badań eksperymentalnych przeprowadzono dla normalnego i awaryjnego trybu pracy napędu w zakresach prędkości ponad znamionowych oraz bardzo niskich.

  • Badania doświadczalne przyczepności
    • Marcin Burdziński
    • Maciej Niedostatkiewicz
    2020 Full text Builder

    W artykule przedstawiono podstawowe informacje dotyczące zjawisko przyczepności stalowych prętów i betonu, w sposób szczegółowy opisano autorski program badań tego zjawiska

  • Badania eksperymentalne stalowych łączników balkonowych typu podwójnego
    • Maciej Solarczyk
    • Paweł Piotrkowski
    • Maciej Niedostatkiewicz
    2020

    Artykuł stanowi prezentację wyników badań eksperymentalnych przeprowadzonych na czterech pełnowymiarowych prefabrykowanych zestawach balkonowych o wymiarach (szerokość × długość × wysokość): 2,0 m × 2,78 m × 0,186 m (w spadku do 0,17 m). Zestawy składały się z żelbetowych płyt (balkonowej oraz stropowej), połączonych ze sobą łącznikami balkonowymi typu podwójnego (łącznik składający się z dwóch prętów rozciąganych oraz dwóch blach ścinanych, połączonych ze sobą za pomocą środnika przekroju ceowego). Publikacja jest kontynuacją tematyki podjętej w pracy [1]. Przeanalizowano wpływ zmiennych parametrów na nośność elementów. Przedstawiono przegląd literatury naukowej z zakresu łączników balkonowych [2, 3].

  • Badania nieniszczące jakości spoin szyn poddźwigowych na nabrzeżu przeładunkowym T1 w DCT w Porcie Północnym
    • Wojciech Kiełczyński
    • Jacek Haras
    • Marian Siejka
    2020

    Celem podstawowym niniejszego opracowania było sprawdzenie za pomocą NDT jakości spoin wykonanych w ramach prac naprawczych w DCT w roku 2017 (styki szyn poddźwigowych typu A120 na nabrzeżu T1 w DCT Port Północny Gdańsk). W ramach opracowania: 1) Ustalono zakres badań - na podstawie potrzeb Kierownictwa Infrastrukury DCT; b) Analizowano wyniki badań nieniszczących wykonanych w sierpniu 2017r.; c) Wykonano badania UT-puls i MT oraz pomiary ugięcia szyn poddźwigowych na odcinkach 1m wg wskazań Zleceniodawcy; 4) Sporządzono raporty z badań NDT; 5) Opracowano wyniki badań nieniszczących.

  • Badania tribologicznych właściwości nanokompozytowych warstw Ni-P/Si3N4 osadzanych metodą redukcji chemicznej na stopie aluminium AW-7075
    • Kazimierz Czapczyk
    2020 Full text Przemysł Chemiczny

    Przedstawiono wyniki tribologicznych badań warstw nanokompozytowych Ni-P/Si3N4 i niklowych Ni-P osadzonych na stopie aluminium AW-7075 metodą redukcji chemicznej, a także stopu AW-7075 bez powłoki. Warstwy nanokompozytowe wytworzono, stosując azotek krzemu Si3N4 w postaci polidyspersyjnego proszku o wielkości cząstek 20–25 nm. Analizowano wpływ zawartości w materiale warstwy fazy dyspersyjnej na twardość i zużycie ścierne, którą określono metodą ball-on-disc. Topografię powierzchni zbadano metodą stykową za pomocą profilometru. Wprowadzenie cząstek Si3N4 do warstwy Ni-P spowodowało zwiększenie twardości oraz odporności na zużycie ścierne części ze stopu aluminium AW-7075 z osadzoną powłoką nanokompozytową. Warstwy Ni-P/Si3N4 charakteryzowały się lepszymi właściwościami tribologicznymi niż warstwy Ni-P oraz stop AW-7075 i stanowiły dobre zabezpieczenie przed zużyciem ściernym.

  • Badanie jakości sieci komórkowych w przededniu technologii 5G na wybranym przykładzie
    • Przemysław Falkowski-Gilski
    • Tadeus Uhl
    2020 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    Wraz z rosnącą popularnością i dostępnością urządzeń mobilnych, zwiększa się liczba abonentów w sieci. Fakt ten prowadzi do wzrostu świadomości użytkowników, pod kątem jakości treści, które konsumują. Wielu dostawców usług oraz operatorów skupia swoje działania na monitorowaniu parametrów jakościowych QoN (Quality of Network) i QoS (Quality of Service). Niniejsza praca przed-stawia wyniki badań przeprowadzonych na terenie kampusu uniwersyteckiego, uwzględniając ogólną wydajność sieci komórkowych w przededniu technologii 5G.

  • Badanie jakości wybranych produktów
    • Maria Szpakowska
    • Ewa Marjańska
    • Elwira Brodnicka
    • Wojciech Szpakowski
    2020

    W monografii „Badania jakości wybranych produktów” scharakteryzowano siedem grup produktów żywnościowych oraz dwie grupy produktów nieżywnościowych i opisano badania pozwalające na ocenę ich jakości, które można wykonać w laboratorium Katedry Nauk o Jakości Wydziału Zarządzania i Ekonomii Politechniki Gdańskiej. Są to: pieczywo, tłuszcze jadalne, mleko i płynne produkty mleczne, jaja i produkty jajeczne, wody pitne, gazowane napoje bezalkoholowe, produkty przemysłu fermentacyjnego, papier i opakowania z papieru, metale, stopy metali, minerały i kamienie szlachetne. Każdy rozdział opisujący poszczególną grupę produktów składa się z pięciu podroz¬działów: części teoretycznej (podrozdziały 1–4) i praktycznej (podrozdział 5). W części teoretycznej omówiono skład i rodzaje produktów z danej grupy, właściwości fizyko¬chemiczne, organoleptyczne i inne cechy jakościowe oraz – w niektórych przypadkach – procesy technologiczne. W części praktycznej opisano metody wyznaczania niektórych właściwości fizykochemicznych, sposoby oceny jakości wybranych produktów, a także rozpoznawania autentyczności niektórych wyrobów jubilerskich.. Dziewięć rozdziałów opisujących wybrane produkty i badania ich jakości poprzedzono dwoma rozdziałami, w których zaprezentowano sposoby przedstawienia wyników pomiarów i obserwacji oraz analizę błędów pomiarów wielkości fizycznych. Niniejsza książka jest przeznaczona dla studentów kierunków studiów społecznych w zakresie nauk o jakości, a w szczególności ma stanowić bazę do przedmiotu jakość produktu, realizowanego w ramach studiów I stopnia na Wydziale Zarządzania i Ekonomii Politechniki Gdańskiej. Ze względu na zamieszczone schematy blokowe procesów technologicznych produkcji wybranych produktów książka ta będzie pomocna dla studentów realizujących przedmiot technologia produktu. Opracowanie powinno być przydatne również studentom lub wykładowcom z innych uczelni, zajmującym się szeroko pojętą jakością różnych produktów oferowanych konsumentom w handlu.

  • Badanie jakościowe zachowań w organizacji
    • Tomasz Ochinowski
    • Marta Szeluga-Romańska
    2020

    Publikacja jest zbiorem specjalistycznych tekstów przygotowanych przez polskich psychologów pracy, organizacji oraz zachowań konsumenckich. To rezultat współdziałania ekspertów z wielu dziedzin, których łączy ciekawość zachowań ludzkich w przestrzeni biznesu. Publikacja prezentuje psychologię biznesu szeroko, zgodnie z aktualnymi programami kształcenia w prestiżowych ośrodkach, ale zakorzenia ją w polskich realiach, uwzględniając pokaźny dorobek polskich teoretyków i badaczy.

  • Badanie wytrzymałości połączeń klejonych węglowych i aluminiowych elementów zawieszenia bolidu formuły student
    • Michał Formela
    • Adrian Pluto-Prondziński
    • Andrzej Grucza
    2020

    Podczas projektowania innowacyjnego zawieszenia, które pozwoliłoby uzyskać przewagę nad konkurencyjnymi bolidami Formuły Student, postawiono warunek, aby jak najbardziej zmniejszyć masę elementów. Używane do tej pory rurki wykonane ze stali S235 o średnicy zewnętrznej 12 mm i grubości 2 mm oraz w miejscach bardziej obciążonych o średnicy zewnętrznej 14 mm i grubości 2 mm cechowały się znaczną masą. Ich głównym zadaniem jest połączenie ramy bolidu ze zwrotnicą (rys. 1 i rys. 2). Po porównaniu własności wytrzymałościowych rurki stalowe postanowiono zastąpić kompozytowymi rurkami z włókna węglowego. Wiele zespołów, mających już wieloletnie doświadczenie, zajmujących corocznie znaczące pozycje w zawodach Formuły Student zdecydowało, że takie rozwiązanie korzystnie wpływa na zachowanie się bolidu. W starym zawieszeniu końcówki wpustów zabezpieczano promieniową zawleczką, ale przy kompozycie takie rozwiązanie mogło nie być trwałe, więc zdecydowano się na połączenie klejone. Głównym problemem mogłoby być wykonanie promieniowego otworu w kompozycie, co nie tylko zmniejsza wytrzymałość samej rurki kompozytowej, ale podczas wiercenia lub powiercenia uszkadza poszczególne włókna, które są wcześniej nawijane w kolejnych warstwach na siebie. Próbki, a później gotowe elementy zawieszenia bolidu, wykonywane w ten sposób nie gwarantują powtarzalności, co za tym idzie, nie można jasno określić, czy dany element nie ulegnie uszkodzeniu bądź nawet zniszczeniu podczas wyścigu. Dlatego do połączenia elementów zawieszenia (metalowych insertów i rurek kompozytowych) zdecydowano się na połączenie klejone.Układ kinematyczny zawieszenia został zaprojektowany w taki sposób, że na wahacze działają w dużej mierze wyłącznie siły rozciągające i ściskające. Przekłada się to na powstawanie naprężeń ścinających w połączeniu rurka-wpust. W tym celu zaplanowano badanie rozciągania statycznego, które miało na celu sprawdzenie wytrzymałości na rozciąganie elementów zawieszenia (metalowych insertów i rurek kompozytowych) połączonych klejowo. Jest to ważniejsze tym bardziej, że w kartach technologicznych klejów z reguły podawana jest jedynie statyczna wytrzymałość połączeń (naprężenia normalne). Spośród wielu rodzajów kleju, które przeznaczone są do spajania kompozytów i metali wytypowano trzy, które uznano za umożliwiające uzyskanie najbardziej wytrzymałego połączenia klejonego. Kleje użyte do badania to: SCIGRIP SG5000-06, LOCTITE EA3423 i VIVTEK X705.06.B.

  • Balancing energy consumption in limited power grid with active front-end and three phase dual active bridge system
    • Konstantin Vorobev
    • Ryszard Strzelecki
    • Nikolai Poliakov
    2020 Full text

    Paper deals with simulation analysis of bidirectional power converters system for charging station of electric vehicle in condition of limited power source in city infrastructure. In case of incapability to provide additional power supply through the grid by virtue of historical, architectural and economic reasons it is possible to solve this issue by implementation of mobile battery-powered supply source. The proposed bidirectional power converters system for consist of three-phase dual active bridge two-directional converter and active front end. Bidirectional power converters system operation modes considered in the paper include transmission of energy from both the battery station, and grid and the joint power supply with battery and grid

  • Balkan Stock Exchanges – Consideration of the Length of the Estimation Window in Similar Markets
    • Katarzyna Kubiszewska
    • Marcin Potrykus
    2020 Full text European Research Studies Journal

    Purpose: We study if capital markets in the Balkan are closely and positively related in terms of rate of return, risk, efficiency, and maximum cumulative loss in relation to different lengths of the estimation window. Design/Methodology/Approach: The research was carried out for the period from 01/01/2017 to 31/12/2019 using portfolio analysis. It was divided into an estimation window (01/01/2019 to 31/12/2019) and another with observations from the remaining days. The results were compared with a naive strategy. Four-element portfolios, consisting of three investments in companies from a given stock exchange and one investment in gold as a haven, were created. After determining all possible combinations of portfolios for each stock exchange and for all lengths of estimation window, the obtained results for rate of return, risk, efficiency, for each length of estimation window were averaged and were subjected to correlation analysis. Findings: In Balkan capital markets, a change in the length of the estimation window (optimal length 120 observations) had the same impact on the results for investment portfolio risk, efficiency, and maximum cumulative loss, but not for the rate of return. Practical Implications: An investor from one of the Balkan countries using a strategy based on portfolio theory would not be able to gain a competitive advantage over another investor from this region if he built a portfolio based on the same number of observations from the past. The investor should construct an investment portfolio based on historical data from the previous six months. Longer estimation periods are not recommended, as the results for the studied portfolio were worse than a naive strategy. Originality/Value: The study concentrates on the unique region of Europe, which was the subject of system transformation latest therefore it should not be compared directly to the current achievements in the stock changes which tradition of operation is longer.