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Gdańsk University of Technology

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  • Establishing the allosteric mechanism in CRISPR‐Cas9
    • Łukasz Nierzwicki
    • Pablo Ricardo Arantes
    • Aakash Saha
    • Giulia Palermo
    2021 Full text Wiley Interdisciplinary Reviews-Computational Molecular Science

    Allostery is a fundamental property of proteins, which regulates biochemical information transfer between spatially distant sites. Here, we report on the critical role of molecular dynamics (MD) simulations in discovering the mechanism of allosteric communication within CRISPR‐Cas9, a leading genome editing machinery with enormous promises for medicine and biotechnology. MD revealed how allostery intervenes during at least three steps of the CRISPR‐Cas9 function: affecting DNA recognition, mediating the cleavage and interfering with the off‐target activity. An allosteric communication that activates concerted DNA cleavages was found to led through the L1/L2 loops, which connect the HNH and RuvC catalytic domains. The identification of these “allosteric transducers” inspired the development of novel variants of the Cas9 protein with improved specificity, opening a new avenue for controlling the CRISPR‐Cas9 activity. Discussed studies also highlight the critical role of the recognition lobe in the conformational activation of the catalytic HNH domain. Specifically, the REC3 region was found to modulate the dynamics of HNH by sensing the formation of the RNA:DNA hybrid. The role of REC3 was revealed to be particularly relevant in the presence of DNA mismatches. Indeed, interference of REC3 with the RNA:DNA hybrid containing mismatched pairs at specific positions resulted in locking HNH in an inactive “conformational checkpoint” conformation, thereby hampering off‐target cleavages. Overall, MD simulations established the fundamental mechanisms underlying the allosterism of CRISPR‐Cas9, aiding engineering strategies to develop new CRISPR‐Cas9 variants for improved genome editing.

  • Estimation of Average Speed of Road Vehicles by Sound Intensity Analysis
    • Józef Kotus
    • Grzegorz Szwoch
    2021 Full text SENSORS

    Constant monitoring of road traffic is important part of modern smart city systems. The proposed method estimates average speed of road vehicles in the observation period, using a passive acoustic vector sensor. Speed estimation based on sound intensity analysis is a novel approach to the described problem. Sound intensity in two orthogonal axes is measured with a sensor placed alongside the road. Position of the apparent sound source when a vehicle passes by the sensor is estimated by means of sound intensity analysis in three frequency bands: 1 kHz, 2 kHz and 4 kHz. The position signals calculated for each vehicle are averaged in the analysis time frames, and the average speed estimate is calculated using a linear regression. The proposed method was validated in two experiments, one with controlled vehicle speed and another with real, unrestricted traffic. The calculated speed estimates were compared with the reference lidar and radar sensors. Average estimation error from all experiment was 1.4% and the maximum error was 3.2%. The results confirm that the proposed method allow for estimation of time-averaged road traffic speed with accuracy sufficient for gathering traffic statistics, e.g., in a smart city monitoring station.

  • Estimation of structural stiffness with the use of Particle Swarm Optimization
    • Michał Mazur
    • Marek Galewski
    • Krzysztof Kaliński
    2021 Full text Latin American Journal of Solids and Structures

    The paper presents the theoretical background and four applications examples of the new method for the estimation of support stiffness coefficients of complex structures modelled discretely (e.g. with the use of the Finite Element Model (FEM) method based on the modified Particle Swarm Optimization (PSO) algorithm. In real-life cases, exact values of the supports’ stiffness coefficients may change for various reasons (e.g. order of fastening, state of the contact surfaces, environment changes, etc.). Becaus e of the unknown coefficients, reliable simulations of fixed structure (i.e. mounted, assembled, not in a free-free state) are difficult to perform. The method serves as a tool to obtain good correlation between the FEM of a structure and the experimental data. Simple modal tests are required to estimate the first few modes of the fixed system. The FEM of the structure is considered in a free-free state and the support stiffness coefficients of the FEM are estimated by the proposed method. Further simulations with test - tuned and correlated complete FEM could be performed in time or frequency domain.

  • Estimation of the size of informal employment based on administrative records with non‐ignorable selection mechanism
    • Maciej Berȩsewicz
    • Dagmara Nikulin
    2021 JOURNAL OF THE ROYAL STATISTICAL SOCIETY SERIES C-APPLIED STATISTICS

    In this study, we used company level administrative data from the National Labour Inspectorate and The Polish Social Insurance Institution in order to estimate the prevalence of informal employment in Poland in 2016. Since the selection mechanism is non‐ignorable, we employed a generalization of Heckman’s sample selection model assuming non‐Gaussian correlation of errors and clustering by incorporation of random effects. We found that 5.7% (4.6%, 7.1%; 95% CI ) of registered enterprises in Poland, to some extent, take advantage of the informal labour force. Our study exemplifies a new approach to measuring informal employment, which can be implemented in other countries. It also contributes to the existing literature by providing, to the best of our knowledge, the first estimates of informal employment at the level of companies based solely on administrative data

  • Estimators of covariance matrices in Msplit(q) estimation
    • Zbigniew Wiśniewski
    • Marek Zienkiewicz
    2021 SURVEY REVIEW

    This paper proposes methods for the determination of covariance matrices of Msplit(q) estimators. The solutions presented here allow Msplit(q) estimation to be supplemented by the operations from the domain of accuracy analysis (especially that concerning estimators of parameters). Theoretical forms of covariance matrices of Msplit(q) estimators were established using the empirical influence functions and the equivalent covariance matrices of observation errors. The estimators of covariance matrices of Msplit(q) estimators were determined based on the adopted statistical observation models and their random errors. The unknown variance coefficients of these models were estimated employing the principles of square estimation.

  • Eurozone or National Inflation Projections: Which has Greater Impact on Consumer Expectations?
    • Magdalena Szyszko
    • Karolina Tura-Gawron
    2021 Full text PANOECONOMICUS

    We compare the dependence of consumer inflation expectations on European Central Bank (ECB) inflation projections with that on national central bank (NCB) projections in four economies: Austria, Belgium, Finland, and Germany. We aim to assess whether the information published by central banks affects consumers, and whether inflation projections published by NCBs are more relevant to consumers than those published for the entire Eurozone. Inflation expectations were obtained from the Business and Consumer Surveys conducted by the Directorate General for Economic and Financial Affairs of the European Commission and quantified using the probabilistic method. The methodology covers: (1) forecast encompassing tests, (2) the Granger causality test, and (3) impulse response analysis complemented by (4) forecast error variance decomposition. The results suggest that the ECB outlook constitutes a more important factor in expectation formation. This article adds to the existing literature by comparing the impact of common and national projections on consumer expectations.

  • Evaluating architecture students' knowledge of the history of architecture by tests and by drawings: a comparative analysis
    • Maria Sołtysik
    2021 Full text World Transactions on Engineering and Technology Education

    The methods of evaluating students’ knowledge in architectural education, and in particular in education on history of architecture, are specific in many respects. Apart from checking the general knowledge of history concerning chronology, artistic trends, styles, main objects and architects, it should also check students’ ability to analyse the historic architecture in a drawing form. Such a form of presenting architecture has proven to be the most comprehensive and aimed on understanding its development throughout the ages. Thus, the methods of evaluating students’ historical knowledge at GUT include two main methods of examination – tests and drawings. Both methods and their results were closely investigated and compared after the first semester exam in the academic year 2020/2021. A comparative analysis was conducted in context of correctness, efficiency, usefulness and difficulty, both from the perspective of the students examination results and the student questionnaire

  • Evaluating Industry 4.0 Implementation Challenges Using Interpretive Structural Modeling and Fuzzy Analytic Hierarchy Process
    • Ahmad Reshad Bakhtari
    • Mohammad Waris
    • Cesar Sanin
    • Edward Szczerbicki
    2021 Full text CYBERNETICS AND SYSTEMS

    The fourth industrial revolution known as Industry 4.0 is reshaping and evolving the way industries produce products and individuals live and work therefore, gaining massive attraction from academia, business and politics. The manufacturing industries are optimistic regarding the opportunities Industry 4.0 may offer such as, improved efficiency, productivity and customization. The present research contributes to the Industry 4.0 literature by identifying, modelling, analyzing and prioritizing the challenges in implementing Industry 4.0 in manufacturing industries. In doing so, the paper first introduces the interpretive structural modelling (ISM) to develop the hierarchical relationships among the challenges and analyzes their mutual interactions. Further, ‘Matrice d’Impacts Croises Multiplication Appliquee aun Classement’ (MICMAC) analysis is used to categorize the challenges into four categories namely, autonomous, driver, dependent and linkage based on their driving power and dependence power. Moreover, fuzzy-analytic hierarchy process (F-AHP) methodology is used to prioritize the challenges based on three criteria; driving power, dependence power and change management. The hierarchical model developed through ISM methodology shows that “lack of vision and leadership from top management (C12), lack of skills training program and education (C2) and uncertainty of return on investment (C9)” are the major challenges in implementing Industry 4.0 in manufacturing industries. The findings of F-AHP analysis suggests that “lack of vision and leadership from top management (C12), lack of skilled workforce (C3), lack of skills training program and education (C2) and uncertainty of return on investment (C9)” are some of the major challenges of implementing Industry 4.0. Finally, the obtained results show how challenges affect other so that to uncover the root cause triggering the other challenges. The industrial practitioners and managers can then take advantage of these analyzes to know which challenge acts as the main barrier in implementing Industry 4.0 and to be focused first in order to reach a solution.

  • Evaluating the antibacterial activity of muramyl dipeptide derivatives, retro-tuftsin derivatives, and anthraquinone oligopeptides against a range of pathogenic bacteria
    • Magdalena Wysocka
    • Krystyna Dzierzbicka
    • Beata Krawczyk
    2021 Full text Acta Biochimica Polonica

    Search for new and efficient antibiotic is crucial because of microbial drug resistance and problems with side effects of the administered medication. In this study, we evaluate the in vitro microbiological activity of muramyl dipeptide derivatives, retro-tuftsin derivatives (i.e., tuftsin with reversed amino acid sequences), and combinations of retro-tuftsin derivatives with substituted anthraquinones. The potency of the investigated derivatives towards methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae ESBL (extended-spectrum β-lactamases) was compared based on the spectroscopically-measured minimal inhibitory concentrations (MIC values). The bacterial growth have also been studied with different concentrations of compounds. Statistical analysis of the results revealed that certain modifications lead to promising activity against S. aureus (anthraquinone analogue – 3c and retro-tuftsin derivative – 2b), while other derivatives exhibit activity against P. aeruginosa (muramyl dipeptide derivative – 1d and retro-tuftsin derivative – 2b). The obtained results of microbiological activity indicate that the structure of the tested compounds may be the basis for further modifications.

  • Evaluating the convenience and safety effects of bicycle lanes in Gdańsk
    • Romanika Okraszewska
    • Karolina Kijewska
    • Joanna Wachnicka
    • Miroslava Mikusova
    2021 Full text Archives of Civil Engineering

    Bicycle lanes are lanes marked on a road and dedicated for exclusive use for cyclists.. Because they combine bike and motor traffic they provide directness and flow. However, a shared use of streets could result in bicycle-car accidents. Following up on the good practice Western countries have in planning cycle infrastructure, Gdańsk has recently introduced bike lanes on a few streets. The aim of the research was to assess the attractiveness and safety of bike lanes as a relatively new and rare solution in Gdansk. The attractiveness was assessed using the multi-criteria method. The data for the assessment came from surveys and fieldwork (inventory, observation of cyclist behaviour, traffic counts). Additionally, safety information was supplemented with police statistics on collisions and accidents. The results show that the level of bike lane usage is rather high (more than 70%). However, 80% of the respondents do not find them as attractive as separated bike paths. The advantages indicated by bike lane users included speed, surface quality, and comfort. Those who avoiding bike lanes have pointed to insufficient sense of safety. The main problems were identified such as speed and volume of motor traffic, width of bicycle lane, surface quality and parking places located next to bike lanes. The conclusions from the research are consistent with the literature. The findings could improve the attractiveness and safety of bike lanes in Gdańsk if implemented by bike infrastructure planners and designers

  • Evaluating the influence of radiative heat flux on convective heat transfer from a vertical plate in air using an improved heating plate
    • Michał Ryms
    • Witold Lewandowski
    2021 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER

    This article examines the influence of radiative heat flux on the accuracy of the results of free convective heat transfer in air. In order to carry out these tests, based on the experience gained during the operation of a plate heated on one side, compensated by a reverse heat loss flux counter-heater, a unique double-sided heating sandwich plate was designed and built, consisting of three thin epoxy resin plates reinforced with glass fibre. The paths of surface resistance thermometers were etched using photolithography on the two outer plates laminated on one side with copper. The traces of two resistance heaters were etched on both sides of the third, bilaterally laminated middle plate. This paper provides a detailed technical description of the new type of plate, the method of its implementation and determination of its operational range, calibration procedures (separately for integrated thermometers and heaters). Also described are the methods for conducting experimental tests in the vertical using the balance method in air and in water, and the gradient method using a thermal imaging camera and a detection mesh in order to validate the results obtained.

  • Evaluating the Internal and External Usability of Mobile Technologies in Facilitating Knowledge Transfer
    • Michał Kuciapski
    • Paweł Weichbroth
    2021 Full text

    A worker’s performance and productivity depend on a variety of factors including knowledge, to be essential for self-effectiveness and self-efficacy. In the literature, knowledge transfer is argued to enhance the quality of work, and therefore, its value. When addressing this issue, the latest studies have considered and evaluated the use of mobile technologies, which are evidenced to improve a worker’s capacity and skills. However, only a few have investigated the impact of the internal and external usability of mobile technologies in facilitating knowledge transfer. This study draws upon evidence from a survey (n = 237) which shows that both internal and external usability positively influence knowledge transfer. The results of this research shed new light on the importance of mobile technology acceptance by employees, providing a better understanding of how and why rich usability facilitates knowledge transfer and eventually impacts their performance and productivity.

  • Evaluation and start-up of an electro-Fenton-sequencing batch reactor for dairy wastewater treatment
    • Mohammad Reza Heidari
    • Mohammad Malakootian
    • Grzegorz Boczkaj
    • Xun Sun
    • Yang Tao
    • Shirish H. Sonawane
    • Hakimeh Mehdizadeh
    2021 Full text Water Resources and Industry

    This study examined the performance of an integrated wastewater (WW) treatment system, namely an electro-Fenton (EF)-sequencing batch reactor (SBR), for dairy industry WW. The EF process was used as the first stage of the SBR. It degrades bio-refractory compounds via advanced oxidation processes, thereby resulting in the formation of simple biodegradable intermediates. Several factors, including the hydraulic retention time (HRT), sludge volume index (SVI), and sludge retention time (SRT) of the EFSBR, were optimized. The effectiveness was studied for 1 y laboratory-scale experiments under stable conditions (HRT of 10 h, SRT of 15 d, mixed liquor suspended solids concentration of 3500 mg/L, and SVI of 89), which revealed 99% chemical oxygen demand, 97% total nitrogen, and 95% total phosphorus removal. Thus, the developed system is economically feasible and superior to other conventional biological treatment systems.

  • Evaluation of antimicrobial activities of powdered cuttlebone against Klebsiella oxytoca, Staphylococcus aureus, and Aspergillus flavus
    • Ghazal Yazdanpanah
    • Neda Javid
    • Zhila Honarmandrad
    • Najmeh Amirmahani
    • Alireza Nasiri
    2021 Full text Environmental Health Engineering and Management Journal

    Background: The presence of medicines in the environment is considered as a serious threat to the human health. The entrance of these substances into the water sources causes soil pollution, which eventually leads to the environmental pollution and it creates some problems for the public health. Also, increasing antibiotic resistant bacteria has attracted the attention of researchers to the use of natural resources such as marine products, for producing new antibiotics. The aim of this study was to evaluate antimicrobial activities of powdered cuttlebone against Klebsiella oxytoca, Staphylococcus aureus, and Aspergillus flavus. Methods: At first, cuttlebones were washed, dried, and powdered. Then, the powdered cuttlebone was characterized. In the next step, its antimicrobial activities were evaluated using agar well diffusion technique, and minimum inhibitory concentration (MIC) was calculated. Results: The powdered cuttlebone was found to be effective against K. oxytoca (24 mm, MIC: 10-1 mg/mL), but no antimicrobial response was found against S. aureus. Also, the powdered cuttlebone antifungal activity and MIC against A. flavus were recorded 23 mm and 10-1 mg/mL, respectively. Conclusion: The obtained results suggest antimicrobial activities of powdered cuttlebone, which are concentration dependent. Furthermore, cuttlebone can be used as an accessible natural source to provide novel, low cost, and safe antimicrobial agents.

  • Evaluation of aspiration problems in L2 English pronunciation employing machine learning
    • Magdalena Piotrowska
    • Andrzej Czyżewski
    • Tomasz Ciszewski
    • Grazina Korvel
    • Adam Kurowski
    • Bożena Kostek
    2021 Full text Journal of the Acoustical Society of America

    The approach proposed in this study includes methods specifically dedicated to the detection of allophonic variation in English. This study aims to find an efficient method for automatic evaluation of aspiration in the case of Polish second-language (L2) English speakers’ pronunciation when whole words are analyzed instead of particular allophones extracted from words. Sample words including aspirated and unaspirated allophones were prepared by experts in English phonetics and phonology. The datasets created include recordings of words pronounced by nine native English speakers of standard southern British accent and 20 Polish L2 English users. Complete unedited words are treated as input data for feature extraction and classification algorithms such as k-nearest neighbors, naive Bayes method, long-short term memory, and convolutional neural network (CNN). Various signal representations, including low-level audio features, the so-called mid-term and feature trajectory, and spectrograms, are tested in the context of their usability for the detection of aspiration. The results obtained show high potential for an automated evaluation of pronunciation focused on a particular phonological feature (aspiration) when classifiers analyze whole words. Additionally, CNN returns satisfying results for the automated classification of words containing aspirated and unaspirated allophones produced by Polish L2 speakers.

  • EVALUATION OF EFFECTIVENESS OF WATERJET PROPULSOR FOR A SMALL UNDERWATER VEHICLE
    • Lech Rowiński
    2021 Full text Polish Maritime Research

    T he goal of the project described is to replace the existing propulsion system of a small underwater vehicle with a solution less prone to mechanical damage and ensuring a lower risk of the entanglement of fibrous objects suspended in the body of water. Four typical marine screws are utilised in the current design of the vehicle. One possible solution of the problem is the application of waterjet propulsors located inside the body of the vehicle instead. The general condition of the application of the new solution was to secure at least the same motion control capabilities of the vehicle while the basic capability is its propulsion effectiveness at the required speed. Specific features of the considered waterjet propulsor, when compared with their application in surface vessel propulsion, are the lack of the head losses and the low significance of cavitation issues. One of the difficulties in the considered case is the small diameter of the propulsor in comparison to commercially available waterjet units, which have diameters between 0.1 [m] and 1.0 [m]. There is very little data regarding the design and performance of devices in the 0.02 to 0.05 [m] range. Methods utilised to forecast the performance of the new propulsion system are presented and results compared. These were semi-empirical calculations, numerical calculations and tests of real devices. The algorithm that is based on semi-empirical calculations is of particular interest while it offers possibility quick assessment of performance of a propulsor composed of several well defined components. The results indicate the feasibility of modification of the propulsion system for the considered vehicle if all the existing circumstances are taken into account.

  • Evaluation of Langmuir and Freundlich Isotherms for Removal of Cephalexin and Tetracycline Antibiotics By Sistan Sand from Water and Wastewater Samples
    • Massoud Kaykhaii
    • Sayedeh Samaneh Hasheminasab
    • Sayyed Hossein Hashemi
    • Mojtaba Sasani
    2021 Full text Iranian Journal of Analytical Chemistry

    In this research, Sistan sand was used as a natural and inexpensive sorbent for removal of cephalexin and tetracycline antibiotics from water and wastewater samples. For a concentration 60.0 mg L-1 of cephalexin, optimum removal conditions were: pH of the sample 3.0, adsorbent amount 1.0 g, contact time 20.0 min, added amount of sodium chloride to adjust the ionic strength of the solution 7.0 g L-1. Langmuir isotherm was the best fitted model for this adsorption process and adsorbent capacity was calculated to be 0.26 g g-1. This adsorbent was able to remove up to 68.1% of cephalexin from wastewater. In case of tetracycline, for a 90.0 mg L-1 of the analyte, the optimum adsorption conditions were achieved at pH 8.0, 1.0 g of sorbent, contact time of 35.0 min and ionic strength of the solution as sodium chloride of 7.0 g L-1. The isotherm was best in agreement with Freundlich model. Adsorbent capacity was 0.76 g g-1 and up to 76.2% of this antibiotic could be removed from wastewater.

  • EVALUATION OF LIQUID-GAS FLOW IN PIPELINE USING GAMMA-RAY ABSORPTION TECHNIQUE AND ADVANCED SIGNAL PROCESSING
    • Robert Hanus
    • Marcin Zych
    • Volodymyr Mosorov
    • Anna Golijanek-Jędrzejczyk
    • Marek Jaszczur
    • Artur Andruszkiewicz
    2021 Full text Metrology and Measurement Systems

    Liquid-gas flows in pipelines appear in many industrial processes, e.g. in the nuclear, mining, and oil industry. The gamma-absorption technique is one of the methods that can be successfully applied to study such flows. This paper presents the use of thegamma-absorption method to determine the water-air flow parameters in a horizontal pipeline. Three flow types were studied in this work: plug, transitional plug-bubble, and bubble one. In the research, a radiometric set consisting of two sources Am-241 and two Nal(Tl) scintillation detectors have been applied. Based on the analysis of the signals from both scintillation detectors, the gas phase velocity was calculated using the cross-correlation method (CCM). The signal from one detector was used to determine the void fraction and to recognise the flow regime. In the latter case, Multi-Layer Perceptron type artificial neural network (ANN) was applied. To reduce the number of signal features, the principal component analysis (PCA) was used. The expanded uncertainties of gas velocity and void fraction obtained for the flow types studied in this paper did not exceed 4.3% and 7.4% respectively. All three types of analyzed flows were recognised with 100% accuracy. Results of the experiments confirm the usefulnessof gamma-ray absorption method in combination with radiometric signal analysis by CCM and ANN with PCA for comprehensive analysis of liquid-gas flow in the pipeline.

  • Evaluation of Six Degrees of Freedom 3D Audio Orchestra Recording and Playback using multi-point Ambisonic interpolation
    • Tomasz Ciotucha
    • Andrzej Rumiński
    • Tomasz Żernicki
    • Bartłomiej Mróz
    2021 Scopus

    This paper describes a strategy for recording sound and enabling six-degrees-of-freedom playback, making use of multiple simultaneous and synchronized Higher Order Ambisonics (HOA) recordings. Such a strategy enables users to navigate in a simulated 3D space and listen to the six-degrees-of-freedom recordings from different perspectives. For the evaluation of the proposed approach, an Unreal Engine-based navigable 3D audiovisual playback system was implemented. Subjective listening tests were conducted which compare the quality of the prepared walk-through.

  • Evaluation of Street Lighting Efficiency Using a Mobile Measurement System
    • Piotr Tomczuk
    • Marcin Chrzanowicz
    • Piotr Jaskowski
    • Marcin Budzyński
    2021 Full text ENERGIES

    The issue concerns the initial stage of work on a method for performing a rapid assessment of the energy efficiency and illuminance of a street lighting installation. The proposed method is based on simultaneous measurement of illuminance from three lux meters placed on the roof of the vehicle. The data are acquired in road traffic, while the vehicle is driving. The proposed solution will allow in the future to quickly and reproducibly obtain data about the lighting parameters of the studied road section. The illumination values are localised using Global Navigation Satellite System (GNSS). Based on the collected measurement data, with the use of terrain maps, geographic information system (GIS) data and installation design documentation, it will be possible to determine in detail the parameters of energy efficiency indicators for a selected section of the street for the entire street according to the EN13201-5 standard. Preliminary tests were conducted on a section of about one kilometer of street illuminated in class C3. Detailed measurements reveal high variation of obtained energy indicators DP and DE for each road section. The reason for this condition is the variation of power, installation geometry and the presence of obstacles to light.

  • Evaluation of suspended rail vehicle movement parameters
    • Mateusz Kuczyk
    • Piotr Jędrzejewski
    • Paweł Załuski
    2021 Full text Pojazdy Szynowe

    Niniejsza publikacja została poświęcona ocenie parametrów ruchowych koncepcyjnego pojazdu kolei podwieszanej, którą dokonano w oparciu o jego charakterystykę trakcyjną oraz możliwości dynamiczne. W pierwszej kolejności skrótowo opisano konstrukcję proponowanego pojazdu wraz z wyszczególnieniem najważniejszych założeń projektowych. Następnie skupiono się na metodyce oraz samym wykreśleniu charakterystyki trakcyjnej pojazdu, jak również przebiegu jego przyspieszenia w funkcji prędkości. Na koniec poddano ocenie układ hamulcowy poprzez wyznaczenie średniego opóźnienia hamowania w zależności od jego rodzaju. Artykuł ten powstał na podstawie pracy dyplomowej pt. „Koncepcja wagonu silnikowego kolei podwieszanej”, na wydziale Mechanicznym Politechniki Gdańskiej.

  • Evaluation of Temperature Influence on Electrochemical Processes Occurring in a Lithium-Ion Supercapacitor with the Use of Dynamic Electrochemical Impedance Spectroscopy
    • Michał Mielniczek
    • Ewa Janicka
    • Łukasz Gaweł
    • Kazimierz Darowicki
    2021 Full text ENERGIES

    In order to obtain the full impedance characteristics of a lithium-ion capacitor as a function of temperature, the authors proposed the use of dynamic electrochemical impedance spectroscopy. Impedance tests were carried out under wide range of dynamic temperature changes for lithium-ion supercapacitors. Significant differences in electrochemical processes were observed as a result of working temperature. Moreover, the quality of fitting of the equivalent circuits most frequently used in impedance analysis of lithium-ion capacitors was discussed. The proposed methodology allows for a comprehensive characterization of the performance of these devices and provides key information for their optimization in wide range of operations.

  • Evaluation of the Macro- and Micro-Economic Factors Affecting the Financial Energy of Households
    • Tomasz Korol
    2021 Full text ENERGIES

    This paper is an evaluation of the common macro-economic, micro-economic, and social factors affecting households’ financial situations. Moreover, the author’s objective was to develop a fuzzy logic model for forecasting fluctuations in the number of nonperforming consumer loans in a country using the example of Poland. This study represents one of the first attempts in the global literature to develop such a forecasting model based on macro-economic factors. The findings confirm the usefulness of the proposed innovative approach to forecasting the volume of household insolvencies in a country.

  • Evaluation of the Possibility of Identifying a Complex Polygonal Tram Track Layout Using Multiple Satellite Measurements
    • Andrzej Wilk
    • Cezary Specht
    • Władysław Koc
    • Krzysztof Karwowski
    • Jacek Skibicki
    • Jacek Szmagliński
    • Piotr Chrostowski
    • Paweł Dąbrowski
    • Mariusz Specht
    • Marek Zienkiewicz
    • Sławomir Judek
    • Marcin Skóra
    • Sławomir Grulkowski
    2021

    We present the main assumptions about the algorithmization of the analysis of measurement data recorded in mobile satellite measurements. The research team from the Gda´nsk University of Technology and the Maritime University in Gdynia, as part of a research project conducted in cooperation with PKP PLK (Polish Railway Infrastructure Manager), developed algorithms supporting the identification and assessment of track axis layout. This article presents selected issues concerning the identification of a tramway line’s axis system. For this purpose, the supporting algorithm was developed and measurement data recorded using Global Navigation Satellite System (GNSS) techniques was evaluated and analyzed. The discussed algorithm identifies main track directions from multi-device data and repeated position recordings. In order to observe the influence of crucial factors, the investigated route was carefully selected. The chosen tramway track was characterized by its location in various field conditions and a diversified and complex geometric layout. The analysis of the obtained results was focused on the assessment of the signal’s dispersion and repeatability using residuals in relation to the estimated track’s direction. The presented methodology is intended to support railway infrastructure management processes, mainly in planning and maintenance through an efficient inventory of the infrastructure in service.

  • Evaluation of the potential of Microwave Plasma–Atomic Emission Spectrometry for trace elements leaching assessment from the concrete matrix with sewage sludge ash additives
    • Alicja Saczuk
    • Paulina Augustyniak
    • Elżbieta Haustein
    • Bartłomiej Cieślik
    2021

    The management of ash generated during the thermal utilization of sewage sludge is a significant environmental problem requiring an effective technological solution. One alternative way to dispose of sewage sludge is to bind it in concrete as a substitute for part of the aggregate. The properties of the C-S-H phase enable effective immobilization of harmful substances that sewage sludge contains. The amount of individual compounds and elements is variable and fully dependent on the characteristics of the wastewater flowing into the sewage sludge treatment plant. The research investigated the effect of the addition of sewage sludge as a replacement for part of the sand, on the fresh concrete mix and the characteristics of the hardened concrete. The behavior of heavy metals were subjected to observation using microwave plasma–atomic emission spectrometer in three environments, such as nitric acid (pH ≈ 3), artificial ground-water and seawater solutions. The validity of using advanced spectroscopic methods, such as mentioned microwave plasma–ato-mic emission spectrometer, for improving the assessment of the danger of using waste materials in modern building materials was considered.

  • Eventual Convergence of the Reputation-Based Algorithm in IoT Sensor Networks
    • Jacek Lebiedź
    • Piotr Cofta
    • Cezary Orłowski
    2021 Full text SENSORS

    Uncertainty in dense heterogeneous IoT sensor networks can be decreased by applying reputation-inspired algorithms, such as the EWMA (Exponentially Weighted Moving Average) algorithm, which is widely used in social networks. Despite its popularity, the eventual convergence of this algorithm for the purpose of IoT networks has not been widely studied, and results of simulations are often taken in lieu of the more rigorous proof. Therefore the question remains, whether under stable conditions, in realistic situations found in IoT networks, this algorithm indeed converges. This paper demonstrates proof of the eventual convergence of the EWMA algorithm. The proof consists of two steps: it models the sensor network as the UOG (Uniform Opinion Graph) that enables the analytical approach to the problem, and then offers the mathematical proof of eventual convergence, using formalizations identified in the previous step. The paper demonstrates that the EWMA algorithm converges under all realistic conditions.

  • Evolution of Edges and Porosity of Urban Blue Spaces: A Case Study of Gdańsk
    • Justyna Breś
    • Karolina Krośnicka
    2021 Full text Urban Planning

    Current waterfront studies focus mainly on a land-based perspective, failing to include the water side. Water is, however, not just a resource for port and industrial purposes and an edge to the waterfront; it is also a feature of the waterfront and the complex relation between water and city. Thus, the article suggests that water-land edges need to be re-contextualised, taking into consideration also their shape, functionality, and evolution over time. This article therefore introduces the concept of urban blue spaces, that is, spaces that include at least one land-water edge, such as a shoreline or river edge. The types and character of these edges define the porosity of urban blue spaces: Spaces with easy connections, such as boulevards or parks, are highly porous, while fenced areas have low porosity. The research first analyses the existing literature on the spatial and functional characteristics of the land-water edge in port cities, and explores existing typologies of urban blue spaces. The results of this investigation are used to examine the most iconic urban blue space of Gdańsk, the Motława river, over the last 1000 years. The case study shows that the porosity of the Gdańsk urban blue space has been increasing over time, in line with its spatial and functional development from an undeveloped riverbank to a ‘gated’ port and industry area, to urban living spaces today. The article thus presents the whole breadth of urban blue spaces through the case study of the Motława river urban blue space. The spatial evolution of the urban blue space is depicted through the transformation of its land-water edge—from a natural sloping edge to the dominance of vertical edged structures or ones overhanging the surface of the water, to the emergence of spatially ‘blurred’ sloping, slanted, terraced, and floating structures, partially independent of the riverbank. The transformation of the structure of the Motława urban blue space edges increased its complexity over time, from a single-edge structure to a double and multiple-edged one.

  • Evolutionary benefits of personality traits when facing workplace bullying
    • Anna Maria Dåderman
    • Beata Basińska
    2021 Full text PERSONALITY AND INDIVIDUAL DIFFERENCES

    Facing workplace bullying negatively affects physical and mental health, and consequently quality of life and well-being. Personality traits that can help an individual survive and reproduce entail more benefits than costs. Building on two evolutionary theories, Life History Theory and Costly Signaling Theory, this study aims to provide novel insights into how and why personality traits are associated with facing workplace bullying and health-related quality of life. A heterogeneous group of 324 employees in Sweden provided data on workplace bullying, perceived health-related quality of life, and personality traits, controlling for sex and age. We found that openness (HEXACO model) and Machiavellianism (Dark Triad model) served as moderators. Employees with high values of these traits experienced significantly less affected health-related quality of life when facing workplace bullying. Our results indicate evolutionary origins of the personality traits openness and Machiavellianism. A new finding is that possessing, exhibiting, and maintaining traits reflecting a more creative and competitive interpersonal style increases an employee’s ability to survive aversive environments.

  • Examination of selected failure criteria with asymmetric shear stresses in the collapse analysis of laminated shells
    • Jacek Chróścielewski
    • Agnieszka Sabik
    • Bartosz Sobczyk
    • Wojciech Witkowski
    2021 COMPOSITE STRUCTURES

    The paper is concerned with failure analysis of composite shells performed with the usage of the nonlinear 6‐parameter shell theory with drilling rotation degree of freedom. This special theory embodies naturally unlim-ited translations and rotations and is suitable for analysis of irregular shells for instance with various, partic-ularly orthogonal, intersections. The presence of the drilling rotation is inherently accompanied withasymmetry of in‐plane shear stresses and strains which must be taken into account in the composite failure cri-teria. In the paper in general two failure measures are applied: Hashin criterion and Tsai‐Wu criterion whichare appropriately modified to accommodate the stress asymmetry. It is shown, that depending on the used fail-ure criterion, it is possible to obtain slightly different damage zones and values of thefirst ply failure and ulti-mate load. These values are compared with those obtained experimentally.

  • Examination of Spectral Properties of Medicinal Plant Leaves Grown in Different Lighting Conditions Based on Mint Cultivation
    • Mateusz Feldzensztajn
    • Paweł Wierzba
    • Adam Mazikowski
    2021 Full text SENSORS

    Cultivation in controlled environmental conditions can provide good quality medicinal herbs with consistent properties. A sensing system that can determine the contents of medicinal substances in plants using spectral characteristics of leaves would be a valuable tool. Viability of such sensing approach for mint had to be confirmed experimentally, as no data correlating contents of medicinal substances with spectral characteristics of leaves are available, to the best of authors’ knowledge. In the first stage, presented in this paper, the influence of lighting on mint (Mentha rotundifolia) grown on a small hydroponic plantation was studied. Spectral characteristics of leaves were recorded by a spectrophotometer and colorimetric analysis was used to investigate the relationship between these characteristics and the spectrum of lighting. Dry mass yield was measured to test its dependence on the lighting. Dependence of chromaticity of leaves on the spectrum of light used in the cultivation was confirmed. Averaged spectra of leaves are distinguishable using a spectrophotometer and—in most cases—by a human observer. A partial correlation is observed between dry mass yield and the spectrum of lighting. Obtained results justify further research into the correlation between lighting and the contents of biological substances in medicinal plants using spectral characteristics of leaves.

  • Examining Statistical Methods in Forecasting Financial Energy of Households in Poland and Taiwan
    • Tomasz Korol
    2021 Full text ENERGIES

    This paper examines the usefulness of statistical methods in forecasting the financial energy of households. The study’s objective is to create the innovative ratios that combine both financial and demographic information of households and implement them in the forecasting models. To conduct this objective, six forecasting models are developed using three different methods—discriminant analysis, logit analysis, and decision trees separately for households in Poland and Taiwan. Such a research approach will answer the question whether the implementation of constructed ratios can increase effectiveness of the forecasting model and its’ versatility between different economic regions. The research relies on four samples of households—two learning samples and two testing samples (one for each country) consisting of 2400 households from both countries. This study is one of the first attempts in the literature globally to develop forecasting models based on ratios constructed with a combination of two different types of variables—one financial with one demographic variable. Findings confirm the high usability of the proposed innovative approach for forecasting the financial energy of households by taking into account a wide spectrum of diagnostic variables representing the financial strength of consumers.

  • Exergy and Energy Analyses of Microwave Dryer for Cantaloupe Slice and Prediction of Thermodynamic Parameters Using ANN and ANFIS Algorithms
    • Safoura Zadhossein
    • Yousef Abbaspour-Gilandeh
    • Mohammad Kaveh
    • Mariusz Szymanek
    • Esmail Khalife
    • Olusegun D. Samuel
    • Milad Amiri
    • Jacek Dziwulski
    2021 Full text ENERGIES

    The study targeted towards drying of cantaloupe slices with various thicknesses in a microwave dryer. The experiments were carried out at three microwave powers of 180, 360, and 540 W and three thicknesses of 2, 4, and 6 mm for cantaloupe drying, and the weight variations were determined. Artificial neural networks (ANN) and adaptive neuro-fuzzy inference systems (ANFIS) were exploited to investigate energy and exergy indices of cantaloupe drying using various afore-mentioned input parameters. The results indicated that a rise in microwave power and a decline in sample thickness can significantly decrease the specific energy consumption (SEC), energy loss, exergy loss, and improvement potential (probability level of 5%). The mean SEC, energy efficiency, energy loss, thermal efficiency, dryer efficiency, exergy efficiency, exergy loss, improvement potential, and sustainability index ranged in 10.48–25.92 MJ/kg water, 16.11–47.24%, 2.65–11.24 MJ/kg water, 7.02–36.46%, 12.36–42.70%, 11.25–38.89%, 3–12.2 MJ/kg water, 1.88–10.83 MJ/kg water, and 1.12–1.63, respectively. Based on the results, the use of higher microwave powers for drying thinner samples can improve the thermodynamic performance of the process. The ANFIS model offers a more accurate forecast of energy and exergy indices of cantaloupe drying compare to ANN model.

  • Existence of Two Periodic Solutions to General Anisotropic Euler-Lagrange Equations
    • Magdalena Chmara
    2021 Full text TAIWANESE JOURNAL OF MATHEMATICS

    Abstract. This paper is concerned with the following Euler-Lagrange system d/dtLv(t,u(t), ̇u(t)) =Lx(t,u(t), ̇u(t)) for a.e.t∈[−T,T], u(−T) =u(T), Lv(−T,u(−T), ̇u(−T)) =Lv(T,u(T), ̇u(T)), where Lagrangian is given by L=F(t,x,v) +V(t,x) +〈f(t),x〉, growth conditions aredetermined by an anisotropic G-function and some geometric conditions at infinity.We consider two cases: with and without forcing termf. Using a general version ofthe mountain pass theorem and Ekeland’s variational principle we prove the existenceof at least two nontrivial periodic solutions in an anisotropic Orlicz-Sobolev space.

  • Expedited Acquisition of Database Designs for Reduced-Cost Performance-Driven Modeling and Rapid Dimension Scaling of Antenna Structures
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2021 Full text IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION

    Fast replacement models have been playing an increasing role in high-frequency electronics, including the design of antenna structures. Their role is to improve computational efficiency of the procedures that normally entail large numbers of expensive full-wave electromagnetic (EM) simulations, e.g., parametric optimization or uncertainty quantification. Recently introduced performance-driven modeling methods, such as the nested kriging framework, alleviate some of the common difficulties pertinent to conventional modeling methods. These include the curse of dimensionality but also the need for rendering models to be valid for broad ranges of antenna parameters and operating conditions, as dictated by the design utility of the surrogates. The keystone of performance-driven methods is an appropriate confinement of the model domain so that the training data is only acquired in the regions containing high-quality designs. Identification of such regions is realized using a set of so-called reference designs pre-optimized for selected ensembles of performance requirements. The CPU cost of generating the reference points may be considerable and compromise the savings obtained by operating in a constrained domain. In this paper, a technique for automated, reliable and low-cost acquisition of the reference designs is proposed. Our methodology involves inverse sensitivities, iterative correction procedures, and accelerated feature-based gradient search with sparse Jacobian updates. It is validated using three microstrip antenna examples and demonstrated as an efficient tool for lowering the cost of building surrogate models within the nested kriging framework. The intended use of our approach is expedited construction of database designs for constrained modeling frameworks, construction of inverse surrogates as well as procedures for rapid re-design and dimension scaling of antenna structures.

  • Expedited Trust-Region-Based Design Closure of Antennas by Variable-Resolution EM Simulations
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    • Leifur Leifsson
    2021

    The observed growth in the complexity of modern antenna topologies fostered a widespread employment of numerical optimization methods as the primary tools for final adjustment of the system parameters. This is mainly caused by insufficiency of traditional design closure approaches, largely based on parameter sweeping. Reliable evaluation of complex antenna structures requires full-wave electromagnetic (EM) analysis. Yet, EM-driven parametric optimization is, more often than not, extremely costly, especially when global search is involved, e.g., performed with population-based metaheuristic algorithms. Over the years, numerous methods of lowering these expenditures have been proposed. Among these, the methods exploiting variable-fidelity simulations started gaining certain popularity. Still, such frameworks are predominantly restricted to two levels of fidelity, referred to as coarse and fine models. This paper introduces a reduced-cost trust-region gradient-based algorithm involving variable-resolution simulations, in which the fidelity of EM analysis is selected from a continuous spectrum of admissible levels. The algorithm is launched with the coarsest discretization level of the antenna under design. As the optimization process converges, for reliability reasons, the model fidelity is increased to reach the highest level at the final stage. The proposed algorithm allows for a significant reduction of the computational cost (up to sixty percent with respect to the reference trust-region algorithm) without compromising the design quality, which is corroborated by thorough numerical experiments involving four broadband antenna structures.

  • Experience marketing in the service of the “secular religion” of big tech
    • Jan Kreft
    • Monika Boguszewicz-kreft
    2021 Full text

    The article proposes an interpretation of the meaning of experience marketing as a tool in the process of sacralisation of products, and in a broader context – the so-called secular religion accompanying some contemporary big tech organizations. The article is of theoretical nature and the authors have intended to explain how big tech corporations, in line with the concept of experience marketing (digital platforms, in particular), reinterpret their role in relations with users. The aim of the article is to inspire research on the experience marketing in the digital ecosystem in the context of the sacralisation of an organization, its goals, leaders, employees and products. The article has adopted hermeneutics as providing an appropriate theoretical framework for analysis.

  • Experience-Based Product Inspection Planning for Industry 4.0
    • Muhammad Ahmed
    • Farhat Majeed
    • Cesar Sanin
    • Edward Szczerbicki
    2021 Full text CYBERNETICS AND SYSTEMS

    In this paper we describe how our Smart Virtual Product Development (SVPD) system can be used to enhance product inspection planning. The SVPD system is comprised of three main modules, these being the design knowledge management (DKM) module, the manufacturing capability and process planning (MCAPP) module, and the product inspection planning (PIP) module. Experiential knowledge relating to formal decisional events is collected, stored and used by the system in the form of set of experiences (SOEs). Here we discuss the working mechanism of the PIP module and show how experiential knowledge relating to the inspection of products that have features and functions in common can be used to enhance product inspection planning during early stages of product development. Our discussion commences with an introduction to fundamental concepts and a general system overview. We then describe the development of our SVPD system’s PIP module, and a case study we undertook for validation purposes. Results of the case study show that our system is capable of supporting product inspection planning in smart manufacturing, and thus has a vital role to play in Industry 4.0.

  • Experimental analysis of the behaviour of different types of joints in the steel structure model subjected to earthquake loading
    • Tomasz Jaroszewski
    • Tomasz Falborski
    • Robert Jankowski
    2021 Full text Journal of Physics : Conference Series

    The present paper reports the results of the experimental study performed to investigate the behaviour of two different types of joints (destroyed and welded ones) in the model of the steel structure under seismic excitations. The structure was subjected to three earthquakes, namely Kobe, Loma Prieta and Northridge, using the shaking table investigation. The results obtained from the study indicate that there is a significant difference between the behaviour of destroyed joints and welded ones. It was concluded that the destroyed joints experience higher acceleration than the welded joints during different earthquakes.

  • Experimental and Computational Fluid Dynamics Studies on Straight and U-Bend Double Tube Heat Exchangers with Active and Passive Enhancement Methods
    • Rafał Andrzejczyk
    • Tomasz Muszyński
    • Przemysław Kozak
    2021 HEAT TRANSFER ENGINEERING

    In this work, the authors wanted to demonstrate the possibility to increase the heat transfer efficiency by using simple wire coil inserts to create turbulent flow in the boundary layer as well as air blowing into the annulus of the pipe. Experimental investigations were carried out for four heat exchanger constructions, i.e., plain double tube, turbulized double tube, plain U-bend double tube, U-tube with turbulator, plain double tube and U-bend double tube working with two-phase flow conditions (air-water mixture). For these geometries, the values of pressure drop and heat flux were determined. The comparison of heat transfer efficiency was performed based on NTU-e method. The computational fluid dynamics (CFD) technique was also employed to investigate the influence of coiled wire inserts and air bubbly injection at heat transfer, pressure drops and overall efficiency in double tube heatexchangers. For this purpose, six configurations of heat exchangers were meshed and simulated at various flow conditions by using the CFD package Autodesk CFD 2016 (Students & Educators version).

  • Experimental and Numerical Investigation of Tensile and Flexural Behavior of Nanoclay Wood-Plastic Composite
    • M. E. Golmakani
    • Tomasz Wiczenbach
    • Mohammad Malikan
    • Seyed M. Mahoori
    • Victor Eremeev
    2021 Full text Materials

    In this study, the effect of wood powder and nanoclay particle content on composites’ mechanical behavior made with polyethylene matrix has been investigated. The wood flour as a reinforcer made of wood powder was at levels of 30, 40, and 50 wt.%, and additional reinforcement with nanoclay at 0, 1, 3, and 5 wt.%. Furthermore, to make a composite matrix, high-density polyethylene was used at levels of 70, 60, and 50% by weight. Wood-plastic composite (WPC) specimens were manufactured in injection molding. After preparing the specimens, tensile and bending tests were performed on samples. The mechanical properties such as tensile and flexural strength and flexural modulus were measured. Results showed that nanoclay particle content increases flexural modulus, flexural strength, modulus of elasticity, and tensile strength. The experimental test results show that Young’s moduli increased with the volume of wood flour. The biggest modulus of elasticity was achieved in the samples having 50 wt.% of wood powder. Furthermore, the highest value of tensile strength was achieved at the level of 30 wt.%. The highest flexural strength was for the sample containing 50% wood powder by weight. Additionally, a numerical model was made utilizing the Abaqus software using the finite element method (FEM). Comparing the numerical and experimental results, it was found that they are compatible in the linear-elastic and plastic state of the material. There are no crucial differences between experiment and FEM.

  • EXPERIMENTAL AND NUMERICAL INVESTIGATION ON SPECIMEN GEOMETRY EFFECT ON THE CTOD VALUE FOR VL-E36 SHIPBUILDING STEEL
    • Jakub Kowalski
    2021 Full text Polish Maritime Research

    There are special cases in the marine industry, where additional material tests, such as the fracture toughness test, must be performed. Additional fracture toughness tests, such as CTOD (Crack Tip Opening Displacement), are typically performed on three-point bend specimens. The dimension that defines all the specimen dimensions is the thickness of the material to be tested. It is recommended by classification societies (e.g. DNVGL) to test specimens that are twice as high as the material thickness. The width determines the length and, therefore, the weight of the specimen which, for a 100 mm plate is over 140 kg. Current ASTM E1820, BS7448-1 and ISO 12135 testing standards also allow for proportions other than those recommended. This results in a much smaller test piece. Reducing the specimen size allows the testing machine to achieve lower forces than a specimen with a width to thickness ratio of two. This paper presents the effect of changing the specimen geometry on CTOD test results. Research was performed for specimens with a height to thickness ratio of one and two. Abaqus software was used for numerical calculations. The numerical results were, at selected points, verified experimentally.

  • Experimental and numerical investigations of ultimate strength of degradated structures
    • Krzysztof Wołoszyk
    2021 Full text

    The presented work investigates the corrosion influence on the structural behaviour of structural elements. Nine welded large-scale stiffened plates, and 30 standard small specimens have been subjected to the accelerated marine immersed conditions. After corrosion testing, the specimens have been accurately measured in terms of surface characteristics. The coupon specimens were furtherly subjected to tensile loading to develop the mechanical properties conditional on the severity of corrosion degradation. The FE analyses employing the technique of random field modelling were developed and validated against experiments. The stiffened plates were subjected to the compressive loading, and the structural response has been analysed, accounting for initial imperfection, corrosion degradation, welding-induced residual stresses, and material nonlinearity. The numerical models of different accuracy of corrosion degradation models were validated with the experimental results showing that only when non-uniform thickness reduction with subsequent changes in mechanical properties is taken into account, the structural behaviour could be accurately simulated. An analytical formulation allowing for a fast estimation of the structural capacity of corroded stiffened plates and the reliability formulation taking into account the time-dependent development of corrosion degradation has been developed.

  • Experimental and theoretical investigation of conformational states and noncovalent interactions in crystalline sulfonamides with a methoxyphenyl moiety
    • Mateusz Kowalik
    • Jakub Brzeski
    • Małgorzata Gawrońska
    • Katarzyna Kazimierczuk
    • Mariusz Makowski
    2021 CRYSTENGCOMM

    Four sulfonamide derivatives with a methoxyphenyl moiety, namely N-{4-[(2-methoxyphenyl)sulfamoyl] phenyl}acetamide (1a), N-{4-[(3-methoxyphenyl)sulfamoyl]phenyl}acetamide (1b), 4-amino-N-(2- methoxyphenyl)benzenesulfonamide (2a) and 4-amino-N-(3-methoxyphenyl)benzenesulfonamide (2b), have been synthesized and characterized physiochemically by CHNS, MS, FT-IR, 1H NMR, 13C NMR, PXRD and TG methods. Crystal structures were determined by SC-XRD and their conformational and noncovalent interaction properties were examined by both experimental and theoretical (HS, MEPS, NBO, dimerization energy, QTAIM) methods. The conformational flexibility of the bridge connecting two phenyl rings was studied and minimum-energy conformations were theoretically found. The packing architecture and hydrogen bond networks were described by graph set notation. Hirshfeld surface analysis revealed regions of stronger contacts and allowed us to indicate the relative contributions of different noncovalent contacts in the crystal packing. MEPS calculations helped to distinguish the electron rich and electron poor regions and to find the best H-bond donors and acceptors. The use of the QTAIM method enabled us to explain the influence of functional groups and molecular arrangement on the strength of noncovalent interactions in the crystals and overall packing efficiency

  • Experimental and theoretical investigation of the reactivity of [(BDI*)Ti(Cl){η2-P(SiMe3)-PiPr2}] towards selected ketones
    • Aleksandra Ziółkowska
    • Natalia Szynkiewicz
    • Łukasz Ponikiewski
    2021 DALTON TRANSACTIONS

    In this work, we report a new type of reactivity of [(BDI*)Ti(Cl){η2-P(SiMe3)-PiPr2}] (1) towards ketones (BDI* = 2,6-diisopropylphenyl-β-methyldiketiminate ligand). In the reaction of 1 with acetone, cyclopentanone or cyclohexanone, a ketone moiety is inserted into Ti–Pphosphanyl or Ti–Pphosphido bonds to form complexes with a new C–P–P moiety, providing [(BDI*)Ti(Cl){η2-P(SiMe3)-PiPr2-C(Me)2O}] (2a), [(BDI*)Ti(Cl){η2-OC(Me)2P(SiMe3)-PiPr2}] (2b), [(BDI*)Ti(Cl){η2-P(SiMe3)-P(iPr)2-{C(CH2)4}O}] (3a), and [(BDI*)Ti(Cl){η2-P(SiMe3)-P(iPr)2-{C(CH2)5}O}] (4a). Starting complex 1 reacts with cyclohexanone, yielding a monocrystalline complex [{(ArN[double bond, length as m-dash]C(Me)CHC(Me)[double bond, length as m-dash]NAr)C(CH2)5O}Ti(Cl){PiPr2-P(SiMe3)C(CH2)5O}] (4d) with the insertion of two ketone molecules. Interestingly, we found that monoinserted complexes 2a and 3a may be oxidized via a reaction with AgCl, leading to elimination of the –SiMe3 group and oxidation of the titanium atom. This reaction led us to isolate the Ti(IV) complex [(BDI*)Ti(Cl){η2-P-P(iPr)2-{C(CH2)5}O}] (5) in crystalline form. To identify the kinds of products that may be formed and determine which products are the most energetically favoured ones, we conducted a thermodynamic DFT study of 1 towards acetone, cyclopentanone and cyclohexanone. Structures 2a, 2b, 3a, 3e, 4a, 4d, and 5 were characterized by X-ray crystallography, and complex 5 was also identified by NMR spectroscopy.

  • Experimental and theoretical study of a vertical tube in shell storage unit with biodegradable PCM for low temperature thermal energy storage applications
    • Rafał Andrzejczyk
    • Tomasz Kowalczyk
    • Przemysław Kozak
    • Tomasz Muszyński
    2021 Full text APPLIED THERMAL ENGINEERING

    This article presents the experimental investigations of the coconut oil-based TES module for HVAC applications in the ambient and-sub ambient temperature range. To properly study this problem modular experimental module and test loop were developed. Special attention has been paid to study the physical mechanism of the melting/solidification process for natural substance (coconut oil) which has perspectives to be used in thermal energy storage systems. It has been a highlight that the melting/solidification process is much more complex for non-eutectic mixtures and there are limited analytical models witch could be used to design TES working with such substances. Due to the limit of literature data for thermophysical properties of coconut oil own experimental data has been conducted. The article presents both visual and thermal characteristics of the melting and solidification process. It has been confirmed the strong influence of natural convection phenomena at the melting process. What is more, it has been observed that in the case of coconut oil it is better to talk about appearance melting temperature than melting temperature. The experimental analysis confirmed that appearance melting temperature is a function of radial distance from the heat source. In the case of solidification, the influence of natural convection is reduced quickly due to the increasing domination of the conduction heat transfer mechanism. For the solidification temperature profiles are characteristic of the occurrence of subcooling temperature. The level of temperature drop in sub cooling is a function of radial distance from the heat source. It has been also confirmed that in case of melting as well as solidification process the shape of the phase-change profile seems to form a truncated cone (in case of melting inverted). To validate the engineering approach to vast discrepancies in the literature data own experiment has been evaluated with a simple mathematical model to verify the applicability of the literature data in system behavior prediction. Based on the best-fit approach the parameters thermal resistance of the module R = 1.3 W/K was found. Additionally the latent heat of the coconut oil of 178 kJ/kg with Gaussian distribution for melting in temperature of 25 °C and solidification at 21 °C. The proposed correlation can be easily used to optimize latent thermal energy storage cooperated with the HVAC system.

  • Experimental Investigation of Free Convection Heat Transfer from Horizontal Cylinder to Nanofluids
    • Dorota Sawicka
    • Janusz Cieśliński
    • Slawomir Smolen
    2021 Full text ENERGIES

    The results of free convection heat transfer investigation from a horizontal, uniformly heated tube immersed in a nanofluid are presented. Experiments were performed with five base fluids, i.e., ethylene glycol (EG), distilled water (W) and the mixtures of EG and water with the ratios of 60/40, 50/50, 40/60 by volume, so the Rayleigh (Ra) number range was 3 104 Ra 1.3 106 and the Prandtl (Pr) number varied from 4.4 to 176. Alumina (Al2O3) nanoparticles were tested at the mass concentrations of 0.01, 0.1 and 1%. Enhancement as well as deterioration of heat transfer performance compared to the base fluids were detected depending on the composition of the nanofluid. Based on the experimental results obtained, a correlation equation that describes the dependence of the average Nusselt (Nu) number on the Ra number, Pr number and concentration of nanoparticles is proposed.

  • Experimental investigation of performance and emission characteristics of a miniature gas turbine supplied by blends of kerosene and waste tyre pyrolysis oil
    • Tomasz Suchocki
    • Łukasz Witanowski
    • Piotr Lampart
    • Paweł Kazimierski
    • Katarzyna Januszewicz
    • Bartosz Gawron
    2021 ENERGY

    Fossil fuels are non-renewable sources of energy that could be depleted in the near future, giving rise to amajor energy crisis. Scientists from all over the world are working on new technologies to produce fuelnot only from renewable sources but also from waste. This article is concerned with: (i) waste tyremanagement by means of the pyrolysis process, (ii) investigation of physico-chemical parameters ofwaste tyre pyrolysis oil (TPO), and (iii) investigation of performance and emission characteristics of aminiature GTM-140 turbine engine supplied by blends of kerosene and waste tyre pyrolysis oil. Thefinalaim of the research is to determine the influence of the applied blend composition (between 10 and 50%of TPO in the blends) on the performance and emission parameters of a small gas turbine. Turbine inletand outlet temperatures, fuelflow, static thrust, thrust specific fuel consumption (TSFC) and emissionsindex of NOx, CO, SO2are measured in a wide range of turbine load. The differences are the largest for thehighest rotational speeds, where the temperatures, TSFC and emissions of NOxespecially tend to increasewith the increasing fraction of pyrolytic oil in the blends, as compared to those of kerosene. However,emissions of SO2are lower for the all blends in the entire range of load.

  • Experimental Research of an Axial Piston Pump with Displaced Swash Plate Axis of Rotation
    • Paweł Załuski
    2021

    The article describes the influence of displacement of the swash plate rotation axis on the efficiency of axial piston pumps. The dead space volume was defined as the volume of the working chamber in the extreme position of the piston at the end of the pumping phase and its variability was determined as a function of the position of the axis of rotation of the swash plate and the swing angle of swash plate. The influence of swash plate rotation axis displacement on leaks between piston and cylinder was determined. It has been proven that displacement of the swash plate rotation axis reduces the dead space volume and leaks, thus improving the volumetric efficiency visible at small swash plate swing angles. The results of a comparative study of the volumetric and total efficiency of a modified design of a pump that allows the rotation axis to be repositioned are presented. The efficiency curves for the swash plate rotation axis crossing the shaft rotation axis and for the displaced swash plate axis of rotation are compared. The article also presents the author’s construction of an axial piston pump with displaced swash plate rotation axis with a follow-up mechanism of capacity change controlled by a stepper motor. The diagram and view of the test stand are shown, as well as the results of tests of volumetric and hydromechanical pump efficiency.

  • Experimental research of the effect of face milling strategy on the flatness deviations
    • Michał Dobrzyński
    • Daniel Chuchała
    • Kazimierz Orłowski
    • Mateusz Kaczmarczyk
    2021 Full text MATERIALS AND MANUFACTURING PROCESSES

    In this paper the dependencies between face milling strategy of EN AW6082-T6 aluminum alloy samples, with difference thicknesses (6, 8, and 12 mm) and two cold rolling directions, and flatness deviations were presented. Three strategies of milling included different proportions of material removed from both sides of the plates. This approach allowed to control the proportions of residual surface stresses on both sides of the specimens, which were created by the cold rolling process. The face milling strategy involving the symmetrical removal of material from both sides of the sample resulted in the best results of flatness deviations. This strategy was most effective for both rolling directions. It has been observed that the use of an appropriate face milling strategy is particularly important for thin sheets (6 mm thick). In the case of thicker plates (12 mm thick), the selected strategy has less impact on the final values of flatness deviations.

  • Experimental Study of the Resistance to Influence of Aggressive Liquids on Lightweight Concrete
    • Marzena Kurpińska
    • Elżbieta Haustein
    2021 Full text Materials

    In light of the scientific research, the corrosion of concrete structures is one of the main problems that may reduce their durability due to the negative impact of the natural environment. The paper analyzes the influence of the type of component on the selected properties of lightweight concrete subjected to the influence of aggressive liquids. Four concrete mixes were prepared with a granular aggregate made of foamed glass (GEGA) and aggregate made of sintered fly ash (GAA) with the use of a mineral additive: silica fly ash. The prepared lightweight concrete after one year was exposed for 60 days to the following environments: strong acid—HCl, 1% and 2% concentration, weak acid—CH3COOH, 1% and 2% concentration, and an aqueous salt solution of Na2SO4 , 1% and 2% concentration. Then, the compressive strength was tested, and the microstructure analysis of the ready-made lightweight concrete (LWC) was performed. The degree of penetration of aggressive solutions into the cracks of the samples was assessed by means of applying 1% phenolphthalein solution. Changes in the weight of lightweight concrete samples after the test period were estimated. The obtained test results indicate that the decrease in the durability of lightweight concrete can be classified as a long-term process. Concrete with GEGA and GAA showed high resistance to aggressive environments. Moreover, the environment containing chlorides turned out to be the most aggressive, while the environment containing sulfates proved to be the least aggressive. The higher the concentration of the destructive factor was, the faster the corrosion process went. This has been proven by measuring the pH using phenolphthalein and carrying out microscopic examination. Concretes containing aggregates made of foamed glass and sintered fly ash are suitable for use both in traditional construction and in facilities exposed to an aggressive environment (e.g., in the chemical industry and at gas stations.