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  • Estimation of Synchronous Generator and AVR Parameters Based on Gradient and Genetic Methods
    • Krzysztof Dobrzyński
    2023 Pełny tekst Przegląd Elektrotechniczny

    The author present a method for the estimation of selected synchronous generator model and AVR parameters using a gradient and a genetic algorithm. The paper shows an example of model parameter estimation for a turbogenerator, based on the generator voltage time responses obtained during an active and reactive power rejection test

  • Estimation of the Maximum Permissible PV Power to be Connected to the MV Grid
    • Agata Szultka
    • Seweryn Szultka
    • Stanisław Czapp
    • Kamil Makowski
    • Peter Sedlacek
    2023

    In recent decades, a significant increase in the share of renewable energy sources in power grids at various voltage levels has been observed. A number of articles have been published highlighting emerging problems in low-voltage grids with a large share of prosumers and in medium- and high-voltage grids to which photovoltaic (PV) plants are connected. The article analyzes the medium-voltage grid in terms of the possibility of connecting maximum PV power to it, while maintaining the criterion of the proper voltage level in the whole grid. The selection of suitable locations for PV power plants is analyzed, as well as the expected effect of the possible modernization of the grid – replacement of the main line with lines having a larger cross-section. As a result of the analysis, the percentage profits from both presented solutions (PV power plants optimal locations and main power line modernization) have been compared.

  • Estimation of the Regenerative Braking Process Efficiency in Electric Vehicles
    • Jacek Kropiwnicki
    • Tomasz Gawłas
    2023 Pełny tekst Acta Mechanica et Automatica

    In electric and hybrid vehicles, it is possible to recover energy from the braking process and reuse it to drive the vehicle using the batteries installed on-board. In the conditions of city traffic, the energy dissipated in the braking process constitutes a very large share of the total resistance to vehicle motion. Efficient use of the energy from the braking process enables a significant reduction of fuel and electricity consumption for hybrid and electric vehicles, respectively. This document presents an original method used to estimate the efficiency of the regenerative braking process for real traffic conditions. In the method, the potential amount of energy available in the braking process was determined on the basis of recorded real traffic conditions of the analysed vehicle. The balance of energy entering and leaving the battery was determined using the on-board electric energy flow recorder. Based on the adopted model of the drive system, the efficiency of the regenerative braking process was determined. The paper presents the results of road tests of three electric vehicles, operated in the same traffic conditions, for whom the regenerative braking efficiency was determined in accordance with the proposed model. During the identification of the operating conditions of the vehicles, a global positioning system (GPS) measuring system supported by the original method of phenomenological signal correction was used to reduce the error of the measured vehicle’s altitude. In the paper, the efficiency of the recuperation process was defined as the ratio of the accumulated energy to the energy available from the braking process and determined for the registered route of the tested vehicle. The obtained results allowed to determine the efficiency of the recuperation process for real traffic conditions. They show that the recuperation system efficiency achieves relatively low values for vehicle No. 1, just 21%, while the highest value was achieved for vehicle No. 3, 77%. Distribution of the results can be directly related to the power of electric motors and battery capacities of the analysed vehicles.

  • Estimation of the Ultimate Strength of FRP Strips-to-Masonry Substrates Bond
    • Reza Kamgar
    • Houman Ebrahimpour Komleh
    • Anna Jakubczyk-Gałczyńska
    • Robert Jankowski
    2023 Pełny tekst Applied Sciences-Basel

    Fiber-Reinforced Polymers (FRP) were developed as a new method over the past decades due to their many beneficial mechanical properties, and they are commonly applied to strengthen masonry structures. In this paper, the Artificial Neural Network (ANN), K-fold Cross-Validation (KFCV) technique, Multivariate Adaptive Regression Spline (MARS) method, and M5 Model Tree (M5MT) method were utilized to predict the ultimate strength of FRP strips applied on masonry substrates. The results obtained via ANN, KFCV, MARS, and M5MT were compared with the existing models. The results clearly indicate that the considered approaches have better efficiency and higher precision compared to the models available in the literature. The correlation coefficient values for the considered models (i.e., ANN, KFCV, MARS, and M5MT) are promising results, with up to 99% reliability.

  • Estimation of Vehicle Energy Consumption at Intersections Using Microscopic Traffic Models
    • Jacek Oskarbski
    • Konrad Biszko
    2023 Pełny tekst ENERGIES

    This paper addresses issues related to modeling energy consumption and emissions using microscopic traffic simulations. This paper develops a method in which a traffic model is used to calculate the energy needed to travel through selected types of intersections. This paper focuses on energy consumption and derived values of calculated energy, which can be, for example, carbon dioxide emissions. The authors present a review of the scientific literature on the study of factors affecting energy consumption and emissions and methods to estimate them in traffic. The authors implemented an energy consumption model into a microsimulation software module to estimate results as a function of varying traffic volumes at selected types of intersections and for selected traffic organization scenarios. The results of the study show the lowest energy consumption and the lowest emissions when road solutions are selected that contribute to reducing vehicle travel times on the urban street network at higher average vehicle speeds. In addition, the positive impact of the share of electric vehicles in the traffic flow on the reduction of energy consumption and emissivity was estimated.

  • Evaluating aerial laser scanning for seafloor mapping automation Shallow seabed mapping based on airborne Lidar bathymetry
    • Łukasz Janowski
    • Paweł Tysiąc
    • Agnieszka Kubowicz
    2023 GIM International-The Worldwide Magazine for Geomatics

    This article presents a novel methodological approach to understand and assess the suitability of ALB for the automatic classification and mapping of the seabed. ALB allows recording of the depth below the Secchi disk.

  • Evaluating Gelatin-Based Films with Graphene Nanoparticles for Wound Healing Applications
    • Piotr Kamedulski
    • Marcin Wekwejt
    • Lidia Zasada
    • Anna Ronowska
    • Anna Michno
    • Dorota Chmielniak
    • Paweł Binkowski
    • Jerzy P. Lukaszewicz
    • Beata Kaczmarek-Szczepańska
    2023 Pełny tekst Nanomaterials

    In this study, gelatin-based films containing graphene nanoparticles were obtained. Nanoparticles were taken from four chosen commercial graphene nanoplatelets with different surface areas, such as 150 m2/g, 300 m2/g, 500 m2/g, and 750 m2/g, obtained in different conditions. Their morphology was observed using SEM with STEM mode; porosity, Raman spectra and elemental analysis were checked; and biological properties, such as hemolysis and cytotoxicity, were evaluated. Then, the selected biocompatible nanoparticles were used as the gelatin film modification with 10% concentration. As a result of solvent evaporation, homogeneous thin films were obtained. The surface’s properties, mechanical strength, antioxidant activity, and water vapor permeation rate were examined to select the appropriate film for biomedical applications. We found that the addition of graphene nanoplatelets had a significant effect on the properties of materials, improving surface roughness, surface free energy, antioxidant activity, tensile strength, and Young’s modulus. For the most favorable candidate for wound dressing applications, we chose a gelatin film containing nanoparticles with a surface area of 500 m2/g.

  • Evaluating the risk of endometriosis based on patients’ self-assessment questionnaires
    • Krystian Zieliński
    • Dajana Drabczyk
    • Michał Kunicki
    • Damian Drzyzga
    • Anna Kloska
    • Jacek Rumiński
    2023 Pełny tekst Reproductive Biology and Endocrinology

    Background Endometriosis is a condition that significantly affects the quality of life of about 10 % of reproductive-aged women. It is characterized by the presence of tissue similar to the uterine lining (endometrium) outside the uterus, which can lead lead scarring, adhesions, pain, and fertility issues. While numerous factors associated with endometriosis are documented, a wide range of symptoms may still be undiscovered. Methods In this study, we employed machine learning algorithms to predict endometriosis based on the patient symptoms extracted from 13,933 questionnaires. We compared the results of feature selection obtained from various algorithms (i.e., Boruta algorithm, Recursive Feature Selection) with experts’ decisions. As a benchmark model architecture, we utilized a LightGBM algorithm, along with Multivariate Imputation by Chained Equations (MICE) and k-nearest neighbors (KNN), for missing data imputation. Our primary objective was to assess the model’s performance and feature importance compared to existing studies. Results We identified the top 20 predictors of endometriosis, uncovering previously overlooked features such as Cesarean section, ovarian cysts, and hernia. Notably, the model’s performance metrics were maximized when utilizing a combination of multiple feature selection methods. Specifically, the final model achieved an area under the receiver operator characteristic curve (AUC) of 0.85 on the training dataset and an AUC of 0.82 on the testing dataset. Conclusions The application of machine learning in diagnosing endometriosis has the potential to significantly impact clinical practice, streamlining the diagnostic process and enhancing efficiency. Our questionnaire-based prediction approach empowers individuals with endometriosis to proactively identify potential symptoms, facilitating informed discussions with healthcare professionals about diagnosis and treatment options.

  • Evaluation and cellular responses of modulators of TRF1/TRF2 protein’s function as potential anticancer drugs interfering with telomeric shelterin’s function
    • Wioletta Brankiewicz
    2023 Pełny tekst

    A number of proteins that interact with telomeres have been identified in human cells, indicating the high plasticity of human nucleoprotein complex organization. The most important complex is the "shelterin" complex, which consists of six proteins: TRF1, TRF2, TIN2, POT1, TPP1. The TRF1 and TRF2 directly bind to telomeric double-stranded DNA and the TIN2 protein. The TIN2 protein also binds to the TPP1 protein, stabilizing the structure of the entire "shelterin" complex. The PhD thesis presents the characterization of the effect of eleven small molecule compounds (B070, B087, B176, B280, B327, A822, A378, A670, A628, ST50, ST2S), which were designed in silico as potential inhibitors of interactions between TRF1-TIN2 and TRF2-TIN2 proteins. Human breast cancer cell lines were used for the studies: MDA-MB-231 (ER/PR-; HER2/Neu-), BT-20 (ER/PR-; HER2/Neu-), SK-BR-3 (ER/PR-; HER2/Neu+), BT-474 (ER/PR+; HER2/Neu+), MCF-7 (ER/PR+; HER2/Neu-) and T47D (ER/PR+; HER2/Neu), which represent the basic molecular subtypes of breast cancer. Experiments were also carried out on primary HMEC cells and material from patients (invasive ductal breast cancer, ER/PR+; HER2/Neu-). Based on the results obtained using molecular biology methods - starting from toxicity tests, through the advanced technique of fluorescent staining using confocal microscopy and SPR technique - two compounds (A822 and B327) were identified as promising, which were included in a patent application.

  • Evaluation and rationale of the performance of several elastomeric composites incorporating devulcanized EPDM
    • X. Colom
    • F. Carrillo-Navarrete
    • Mohammad Saeb
    • Marc Marín-Genescà
    • Krzysztof Formela
    • J Canavate
    2023 Pełny tekst POLYMER TESTING

    thylene Propylene Diene rubber (EPDM), is present in many applications. However, its crosslinked structure makes difficult its recycling. The use of devulcanized EPDM, (dEPDM) as a component of elastomeric composites, is a real possibility to reuse EPDM scraps. In this study, three matrices (natural rubber (NR), styrene butadiene rubber (SBR) and EPDM rubber) have been tested including devulcanized EPDM as a recycled component. The EPDM previously was devulcanized using a thermomechanical process followed by microwave irradiation. The resulting devulcanized EPDM was blended with the matrixes and then the new compound was vulcanized again. The samples showed a general increase of their mechanical properties and their thermal stability specially marked for NR and SBR. Compositions including about 40 phr dEPDM within the EPDM matrix exhibited a difference in their general behavior that it was manifested by a general decrease in properties compared with lower amounts of dEPDM. In order to further understand this behavior, the samples were analyzed in terms of cross-link density, swelling degree, and scanning electron microscopy. The study of the microstructure of the samples indicated that microagglomerates of dEPDM are formed inside the samples. In case of NR or SBR the agglomerates were very linked to the matrix through the covalent bonds established in the crosslinking process. In the case of the EPDM matrix, the agglomerates presented less interfacial cross-links. The cross-linking takes place preferentially within the dEPDM microdomains and this results in a relative decrease in mechanical properties and thermal stability when compared to NR and SBR.

  • Evaluation of adhesion strength, corrosion, and biological properties of the MWCNT/TiO2 coating intended for medical applications
    • Dorota Rogala-Wielgus
    • Beata Majkowska-Marzec
    • Andrzej Zieliński
    • Katarzyna Roszek
    • Malwina Liszewska
    2023 Pełny tekst RSC Advances

    Multi-wall carbon nanotube (MWCNT) coatings are gaining increasing interest because of their special properties used in many science fields. The titania coatings are known for their improvement of osteoblast adhesion, thus changing the surface architecture. Bi-layer coatings comprising 0.25 wt% of the MWCNTs and 0.30 wt% of titania (anatase structure) were synthesized in a two-stage procedure using the electrophoretic deposition method (EPD). The MWCNT and TiO2 coatings were deposited with voltage and time parameters, respectively, of 20 V and 0.5 min, and 50 V and 4 min. EDS, AFM, SEM, Raman spectroscopy, nano-scratch test, potentiodynamic corrosion tests, wettability studies, and cytotoxicity determined with MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test on human dermal fibroblasts (HDF) and mouse osteoblast precursors (MC3T3), and lactate dehydrogenase (LDH) activity test were carried out on examined surfaces. The prepared MWCNT/TiO2 coating is uniformly distributed by MWCNTs and agglomerated by TiO2 particles of size ranging from 0.1 to 3 mm. Raman spectroscopy confirmed the anatase structure of the TiO2 addition and showed typical peaks of the MWCNTs. The MWCNT/TiO2 coating had higher roughness, higher adhesion strength, and improved corrosion resistance compared to the MWCNT basic coating. The results of biological tests proved that physicochemical properties of the surface, such as high porosity and wettability of MWCNT/TiO2-coated material, would support cell adhesion, but toxic species could be released to the culture medium, thus resulting in a decrease in proliferation.

  • Evaluation of ChatGPT Applicability to Learning Quantum Physics
    • Agata Stefańska
    • Tomasz Stefański
    • Michał Czubenko
    2023

    ChatGPT is an application that uses a large language model. Its purpose is to generate answers to various questions as well as provide information, help solve problems and participate in conversations on a wide range of topics. This application is also widely used by students for the purposes of learning or cheating (e.g., writing essays or programming codes). Therefore, in this contribution, we evaluate the ability of ChatGPT to answer questions in quantum physics. That is, we develop a benchmark consisting of ten questions, whose difficulty is measured on a ten-grade scale. Then ChatGPT answers are evaluated and discussed. In this way, we can measure how well quantum-physics information is processed by this application. Our results demonstrate that ChatGPT does not notice subtle differences between physical terms, and can provide wrong answers to quantum-physics-related questions. It can also provide false mathematical formulas, claim that they are correct and confirm its answers. Note that this AI application is not sure of its answers, and in seven cases it apologizes for the first answer when a user has negated it. To sum up, AI represented by ChatGPT is only able to support students in the process of learning quantum physics at the fundamental level. Moreover, during collective exams in the future, where cheating and the use of AI by students may occur, exam questions should not be descriptive, but should be focused on solving computational problems.

  • Evaluation of electrosynthesized reduced graphene oxide–Ni/Fe/Co-based (oxy)hydroxide catalysts towards the oxygen evolution reaction
    • Karolina Cysewska
    • Marcin Łapiński
    • Marcin Zając
    • Jakub Karczewski
    • Piotr Jasiński
    • Sebastian Molin
    2023 Pełny tekst Beilstein Journal of Nanotechnology

    In this work, the specific role of the addition of graphene oxide (GO) to state-of-the-art nickel–iron (NiFe) and cobalt–nickel–iron (CoNiFe) mixed oxides/hydroxides towards the oxygen evolution reaction (OER) is investigated. Morphology, structure, and OER catalytic activity of the catalysts with and without GO were studied. The catalysts were fabricated via a two-step electrodeposition. The first step included the deposition of GO flakes, which, in the second step, were reduced during the simultaneous deposition of NiFe or CoNiFe. As a result, NiFe-GO and CoNiFe-GO were fabricated without any additives directly on the nickel foam substrate. A significant improvement of the OER activity was observed after combining NiFe with GO (OER overpotential η(10 mA·cm−2): 210 mV) compared to NiFe (η: 235 mV) and GO (η: 320 mV) alone. A different OER activity was observed for CoNiFe-GO. Here, the overall catalytic activity (η: 230 mV) increased compared to GO alone. However, it was reduced in comparison to CoNiFe (η: 224 mV). The latter was associated with the change in the morphology and structure of the catalysts. Further OER studies showed that each of the catalysts specifically influenced the process. The improvement in the OER by NiFe-GO results mainly from the structure of NiFe and the electroactive surface area of GO.

  • Evaluation of fire hazard in electrical installations due to unfavorable ambient thermal conditions
    • Seweryn Szultka
    • Stanisław Czapp
    • Adam Tomaszewski
    • Hayat Ullah
    2023 Pełny tekst Fire

    Evaluation of fire hazard caused by electrical installations is a difficult and important topic, and it limits the possibility of loss of life or health of people, as well as the occurrence of significant property damage. In particular, this hazard was caused by power cables and especially photovoltaic (PV) installations. The authors proved that power cables directly exposed to strong solar radiation are likely to exceed maximum permissible temperature in unfavorable ambient conditions. Overheated and damaged cable insulation can be a source of electric shock and a strong leakage current causing fire. In the case of typical PV connectors (MC4 connectors), the main problem is poor contact at the connections of the PV cables. A poor connection can even cause the connector to melt, as shown in this study. In the paper, the authors present a computer simulation regarding critical thermal points of electrical installations, in particular, of the PV type. It may be an indication of what should be paid attention to when designing and implementing such installations. This is important for the safety of people and buildings.

  • Evaluation of Linkers’ Influence on Peptide-Based Piezoelectric Biosensors’ Sensitivity to Aldehydes in the Gas Phase
    • Tomasz Wasilewski
    • Damian Neubauer
    • Marek Wojciechowski
    • Bartosz Szulczyński
    • Jacek Gębicki
    • Wojciech Kamysz
    2023 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    Recent findings qualified aldehydes as potential biomarkers for disease diagnosis. One of the possibilities is to use electrochemical biosensors in point-of-care (PoC), but these need further development to overcome some limitations. Currently, the primary goal is to enhance their metrological parameters in terms of sensitivity and selectivity. Previous findings indicate that peptide OBPP4 (KLLFDSLTDLKKKMSEC-NH2) is a promising candidate for further development of aldehyde-sensitive biosensors. To increase the affinity of a receptor layer to long-chain aldehydes, a structure stabilization of the peptide active site via the incorporation of different linkers was studied. Indeed, the incorporation of linkers improved sensitivity to and binding of aldehydes in comparison to that of the original peptide-based biosensor. The tendency to adopt disordered structures was diminished owing to the implementation of suitable linkers. Therefore, to improve the metrological characteristics of peptide-based piezoelectric biosensors, linkers were added at the C-terminus of OBPP4 peptide (KLLFDSLTDLKKKMSE-linker-C-NH2). Those linkers consist of proteinogenic amino acids from group one: glycine, L-proline, L-serine, and non proteinogenic amino acids from group two: β-alanine, 4-aminobutyric acid, and 6-aminohexanoic acid. Linkers were evaluated with in silico studies, followed by experimental verification. All studied linkers enhanced the detection of aldehydes in the gas phase. The highest difference in frequency (60 Hz, nonanal) was observed between original peptide-based biosensors and ones based on peptides modified with the GSGSGS linker. It allowed evaluation of the limit of detection for nonanal at the level of 2 ppm, which is nine times lower than that of the original peptide. The highest sensitivity values were also obtained for the GSGSGS linker: 0.3312, 0.4281, and 0.4676 Hz/ppm for pentanal, octanal, and nonanal, respectively. An order of magnitude increase in sensitivity was observed for the six linkers used. Generally, the linker’s rigidity and the number of amino acid residues are much more essential for biosensors’ metrological characteristics than the amino acid sequence itself. It was found that the longer the linkers, the better the effect on docking efficiency.

  • Evaluation of long‑term immunity and protection against T. gondii after immunization with multivalent recombinant chimeric T. gondii proteins
    • Maciej Chyb
    • Bożena Dziadek
    • Katarzyna Dzitko
    • Bartłomiej Tomasz Ferra
    • Malwina Kawka
    • Lucyna Holec-Gąsior
    • Justyna Gatkowska
    2023 Pełny tekst Scientific Reports

    Toxoplasmosis caused by the opportunistic, cosmopolitan protozoan Toxoplasma gondii is one of the most common parasitoses in the world. Although it may prove dangerous or even fatal for immunocompromised individuals, immunoprophylaxis for humans is still nonexistent. Thus, the aim of the current work was to assess the ability of two immunogenic recombinant chimeric T. gondii proteins, SAG2-GRA1-ROP1 (SGR) and SAG1-MIC1-MAG1-GRA2 (SMMG), selected in previous experiments to induce long-lasting immunity when administered with a safe adjuvant. Thus, the determination of immunological parameters and parasite challenge were performed both two weeks after the last boost injection and 6 months postvaccination. Both experimental vaccines triggered specific humoral and cellular responses in immunized C3H/HeOuJ male mice, characterized by the production of specific IgG (IgG1/IgG2a) antibodies in vivo and the synthesis of key Th1/Th2 cytokines by Toxoplasma lysate antigen-stimulated splenocytes in vitro. Although the levels of specific antibodies and cytokine release were in most cases lower six months postimmunization, the protection rates conferred by the vaccination were comparable regardless of the time after the administration of the last vaccine dose. The results indicate that both preparations induce long-lasting immunity, which makes them attractive candidates for further research aimed at boosting their immunogenicity and immunoprotective capacity.

  • Evaluation of structural and electrical properties of multicomponent spinel oxide thin films deposited via spray pyrolysis technique
    • Bartosz Kamecki
    • Jakub Karczewski
    • Grzegorz Cempura
    • Piotr Jasiński
    • Sebastian Molin
    2023 Pełny tekst MATERIALS CHARACTERIZATION

    This work reports the preparation of (Mn,Co,Fe,Ni,Cr)3O4 high-entropy spinel oxide in the form of a ~ 500 nm thin film utilising a facile spray pyrolysis technique. The structural and electrical properties of the layers were characterised after exposure to temperatures in the range of 400–900 ◦C. The as-deposited layers were amorphous, and crystallised upon heat treatment at 500 ◦C. Microstructural analyses proved a homogeneous elemental distribution and the desired Fd-3 m cubic spinel structure. Electrical conductivity measurements indicated a dependence on the processing temperature, with the highest electrical conductivity values (~3 S cm 1 at 700 ◦C) obtained for layers heat-treated at 700 ◦C. The spray pyrolysis technique seems to be well suited to fabricating and exploring spinel-based high-entropy oxides synthesized as thin films, and to studying new compositions containing transition metal cations.

  • Evaluation of the energy efficiency of electric vehicle drivetrains under urban operating conditions
    • Jacek Kropiwnicki
    • Tomasz Gawłas
    2023 Pełny tekst Combustion Engines

    In electric vehicles, as in hybrids vehicles, a very important factor affecting the energy efficiency of the powertrain is the ability to use the regenerative braking energy. Depending on the settings available in electric vehicles, the driver can choose different modes of operation: switch off the regenerative braking mode altogether, select the intensity of regenerative braking, or leave the control system in automatic mode. The last mode is often the only one available on eclectic vehicles, so the driver cannot decide whether to switch off or increase intensity of the regenerative braking. This paper presents a new method for evaluating the energy efficiency of electric vehicle powertrains under urban operating conditions. The presented method uses a procedure for mapping the operating conditions allowing to determine the reference level of energy consumption in relation to those recorded during the identification tests. Identification tests were carried out in the Tri-City area using electric vehicles of different purposes and operating parameters. Performed tests allowed to evaluate the regenerative braking efficiency of tested vehicle, which varies over a relatively wide range, for vehicle A from 33 to 77%, for vehicle B from 27 to 55% and for vehicle C from 36 to 58%. It can be concluded that one of the main factors determining the regenerative braking efficiency is the level of state of charge of the accumulator and the management algorithm used by the vehicle for controlling this parameter.

  • Evaluation of the influence of the opening pressure of a marine Diesel engine injector on the results of numerical simulation of the working cycle and their comparison with the results of the laboratory experiment
    • Patrycja Puzdrowska
    2023 Pełny tekst Combustion Engines

    The article presents the results of a numerical simulation of the working process carried out in a diesel engine. In the applied utility program DIESEL-RK, the laboratory engine Farymann Diesel type D10 was implemented. A selected inoperability of its functional fuel supply system - reduced opening pressure of the injector pinj - was introduced. The values of adequate diagnostic parameters were determined: working gas temperature in the cylinder Tcyl, exhaust gas temperature Texh, combustion (flame) temperature Tcomb and concentration of nitrogen oxides in the exhaust gas NOx. Experimental tests were carried out on the experimental engine with the inoperative condition actually introduced, analogous to the numerical simulation, and the diagnostic parameters Texh and NOx were recorded. The results obtained by numerical simulation of the processes and during the active experiment on the experimental engine were compared.

  • EVALUATION OF THE USE OF M2M-TYPE NB-IoT AND LTE TECHNOLOGIES FOR MARITIME COMMUNICATION SYSTEMS
    • Sławomir Gajewski
    • Agnieszka Czapiewska
    • Małgorzata Gajewska
    2023 Pełny tekst Polish Maritime Research

    The development of IoT (the Internet of Things) wireless transmission opens a new era in communication systems. In the next years, the development and implementation of IoT systems will be very dynamic. It can be seen that the solutions of LTE – NB-IoT (Long Term Evolution – Narrowband IoT) transmission devices are implemented in a wide range of terrestrial solutions, e.g. smart grids. This paper aims to analyse the possibility of the use of NB-IoT technology for maritime communication applications and partially, for some maritime safety solutions, based on signal coverage analysis at sea. An interesting approach is the comparison of the results of NB-IoT coverage to the classic cellular LTE based communication systems. Proposed solutions are based on the practical implementation of a designed specialised data concentrator with implemented gateway and radio modems, for both NB-IoT technology as well as LTE. In the paper, analyses of radio link budget and propagation loss models for sea environment are presented. The coverage analysis is based on real measurements of the efficiency of transmissions using wireless modems implemented in the developed data concentrator.

  • Evaluation of the yield, chemical composition and biological properties of essential oil from bioreactor-grown cultures of Salvia apiana microshoots
    • Agata Krol
    • Adam Kokotkiewicz
    • Marcin Gorniak
    • Aleksandra M. Naczk
    • Bożena Zabiegała
    • Jakub Gebalski
    • Filip Graczyk
    • Daniel Zaluski
    • Adam Bucinski
    • Maria Luczkiewicz
    2023 Pełny tekst Scientific Reports

    Microshoot cultures of the North American endemic Salvia apiana were established for the first time and evaluated for essential oil production. Stationary cultures, grown on Schenk-Hildebrandt (SH) medium, supplemented with 0.22 mg/L thidiazuron (TDZ), 2.0 mg/L 6-benzylaminopurine and 3.0% (w/v) sucrose, accumulated 1.27% (v/m dry weight) essential oil, consisting mostly of 1,8-cineole, β-pinene, α-pinene, β-myrcene and camphor. The microshoots were adapted to agitated culture, showing biomass yields up to ca. 19 g/L. Scale-up studies demonstrated that S. spiana microshoots grow well in temporary immersion systems (TIS). In the RITA bioreactor, up to 19.27 g/L dry biomass was obtained, containing 1.1% oil with up to ca. 42% cineole content. The other systems employed, i.e. Plantform (TIS) and a custom made spray bioreactor (SGB), yielded ca. 18 and 19 g/L dry weight, respectively. The essential oil content of Plantform and SGB-grown microshoots was comparable to RITA bioreactor, however, the content of cineole was substantially higher (ca. 55%). Oil samples isolated from in vitro material proved to be active in acetylcholinesterase (up to 60.0% inhibition recorded for Plantform-grown microshoots), as well as hyaluronidase and tyrosinase-inhibitory assays (up to 45.8 and 64.5% inhibition observed in the case of the SGB culture).

  • Evaluation of thermal cracking probability for asphalt concretes with high percentage of RAP
    • Mariusz Jaczewski
    • Marek Pszczoła
    • Jacek Alenowicz
    • Dawid Ryś
    • Bohdan Dołżycki
    • Piotr Jaskuła
    2023 CONSTRUCTION AND BUILDING MATERIALS

    The paper presents determination of the probability of thermal cracking of asphalt mixtures with different reclaimed asphalt pavement (RAP) content on the basis of laboratory tests and analytical evaluation using thermal stress development method. Probability was evaluated taking into consideration: the type and gradation of the mixture and the quality and content of RAP. Thermal stresses were determined using two models: elastic and viscoelastic. Addition of RAP decreases the low-temperature properties of all the tested asphalt mixtures. In the case of wearing and binder courses, addition of 20% of RAP increases the cracking temperature by around 5–6 ◦C.

  • Evaluation of VSC Impact on Power System Using Adequate P-Q Capability Curve
    • Michal Brodzicki
    • Jacek Klucznik
    • Stanisław Czapp
    2023 Pełny tekst Electronics

    Renewable energy sources, which are becoming increasingly popular, often use a voltage source converter (VSC) for connection to the power system. Assessing the effects of connecting such a source to the power system is essential to ensure the proper operation of the power system and the connected source. For this purpose, it is necessary to know the range of active and reactive power generation by the converter. The authors indicate that the interaction between the power system and the converter affects its range of available active and reactive power. Therefore, a strictly defined range of the converter’s generating capability should not be assumed as invariant, but its capability for a given operating condition of the power system should be determined iteratively. In order to confirm this thesis, the authors analyzed the operation of the VSC-based energy source in an example power system using the PowerFactory software. Extending the calculation procedure to include iterative determination of the converter’s available power range showed a significant influence of the system’s operating state on the converter’s generating capabilities. The results obtained in this work extend the knowledge, and thanks to them, the operation of VSC systems can be modelled more accurately.

  • Event-Triggered Communication in Cooperative, Adaptive Model Predictive Control of a Nuclear Power Plant’s Turbo–Generator Set
    • Pawel Sokolski
    • Tomasz Rutkowski
    • Bartosz Ceran
    • Daria Złotecka
    • Dariusz Horla
    2023 Pełny tekst ENERGIES

    This paper discusses the issue of optimizing the communication between the components of a cooperating control system formed by a pair of MPC controllers of a nuclear power plant turbine set using online recursive least squares identification. It is proposed to use event-triggered communication, i.e., sending information only at selected time instants, as opposed to the standard approach where communication is triggered by time (time-triggered approach). The aim of this paper is to propose a change in the method of information exchange in the case of asynchronous communication between control system components and to prove its suitability for the selected application. Resignation from continuous communication in favor of sending information only at selected moments allows the load on the communication network to be reduced by approximately 90% while maintaining the quality of control.

  • Evolution of Physical Properties of RE 3 Ni 5 Al 19 Family (RE = Y, Nd, Sm, Gd, Tb, Dy, Ho, and Er)
    • Zuzanna Ryżyńska
    • Madalynn Marshall
    • Weiwei Xie
    • Tomasz Klimczuk
    • Michał Winiarski
    2023 Pełny tekst CRYSTAL RESEARCH AND TECHNOLOGY

    Single crystals of RE3Ni5Al19 series (RE = Y, Nd, Sm, Gd, Tb, Dy, Ho, and Er) are grown using the Al self-flux method. The crystal structure is examined by both single crystal and powder X-ray diffraction. Physical properties are studied for the first time for RE3Ni5Al19 (RE = Y, Nd, Gd, Tb, Dy, Ho, and Er) by means of magnetic susceptibility, electrical resistivity, and heat capacity measurements. Complex magnetic behaviors, with up to three transitions present for RE = Sm, Gd, Tb, and Dy, are revealed. Y3Ni5Al19 is found to be a nonmagnetic nonsuperconducting metal (above T = 1.8 K) with weak electron–phonon coupling strength.

  • Evolution towards simplicity in bacterial small heat shock protein system
    • Piotr Karaś
    • Klaudia Kochanowicz
    • Marcin Pitek
    • Przemysław Domański
    • Igor Obuchowski
    • Bartłomiej Tomiczek
    • Krzysztof Liberek
    2023 Pełny tekst eLife

    Evolution can tinker with multi-protein machines and replace them with simpler single-protein systems performing equivalent functions in an equally efficient manner. It is unclear how, on a molecular level, such simplification can arise. With ancestral reconstruction and biochemical analysis, we have traced the evolution of bacterial small heat shock proteins (sHsp), which help to refold proteins from aggregates using either two proteins with different functions (IbpA and IbpB) or a secondarily single sHsp that performs both functions in an equally efficient way. Secondarily single sHsp evolved from IbpA, an ancestor specialized in strong substrate binding. Evolution of an intermolecular binding site drove the alteration of substrate binding properties, as well as the formation of higher-order oligomers. Upon two mutations in the α-crystallin domain, secondarily single sHsp interacts with aggregated substrates less tightly. Paradoxically, less efficient binding positively influences the ability of sHsp to stimulate substrate refolding, since the dissociation of sHps from aggregates is required to initiate Hsp70-Hsp100-dependent substrate refolding. After the loss of a partner, IbpA took over its role in facilitating the sHsp dissociation from an aggregate by weakening the interaction with the substrate, which became beneficial for the refolding process. We show that the same two amino acids introduced in modern-day systems define whether the IbpA acts as a single sHsp or obligatorily cooperates with an IbpB partner. Our discoveries illuminate how one sequence has evolved to encode functions previously performed by two distinct proteins.

  • Examining the Impact of Distance Between VSL Road Signs on Vehicle Speed Variance
    • Andrzej Sroczyński
    • Andrzej Czyżewski
    2023 Pełny tekst IEEE Access

    Variable speed limit (VSL) is an intelligent transportation system (ITS) solution for traffic management. The speed limits can be changed dynamically to adapt to traffic conditions such as visibility and traffic volume, curvature, and grip coefficient of the road surface. The VSL traffic sign location problem and attempts to solve it using computer simulation are presented in this paper. Experiments on a selected road segment, carried out using the traffic simulator, have shown that the proposed method allows the driver’s habits to be taken into account so that the location of road signs can be optimized. The observable effect was a reduction in vehicle speeds and speed variance on critical road segments, translating directly into increased safety and harmonized traffic.

  • Exergetic Analysis of the nCO2PP Cycle with Particular Reference to the Exergy Destruction of Sewage Sludge Due to Gasification
    • Kamil Stasiak
    • Ivar Ståle Ertesvåg
    • Paweł Ziółkowski
    • Dariusz Mikielewicz
    2023

    An exergy analysis is carried out on the negative CO2 emission gas power plant (nCO2PP), which integrates the process sections of fuel preparation, power generation and carbon capture. Processes of exergy destruction are studied with particular focus on the process in the gasification unit of the fuel preparation section, where a large amount of exergy is destroyed in various chemical reactions from sewage sludge to producer gas conversion. The largest exergy losses are observed in the wet combustion chamber and in the fuel line with the gasification process and water condensation in the gas scrubber, amounting to 126 kW, 43-45 kW and 56 kW respectively, which corresponds to efficiencies of 62%, 89% and 84% of these units, while the exergy efficiency of the power plant is 29.5%. The integration of the gasification unit with the gas scrubber is investigated, and a heat exchanger combination is considered. Ambient air changes in relative humidity and, due to increasing global greenhouse gas emissions, CO2 concentration are analysed. Insight into the theoretical operation of the power plant through exergy analysis allows energy efficiency to be increased by improving areas of highest exergy destruction. To represent real power plant operation, the analysis is based on an optimized process simulation calculated using the most accurate published equations of state, verified with experimental thermophysical property data from the literature.

  • Exergy analysis of a negative CO2 emission gas power plant based on water oxy-combustion of syngas from sewage sludge gasification and CCS
    • Ivar S. Ertesvåg
    • Paweł Madejski
    • Paweł Ziółkowski
    • Dariusz Mikielewicz
    2023 Pełny tekst ENERGY

    A power cycle with water-injected oxy-combustion (water cycle) is investigated by exergy analysis. It is fueled with syngas (aka. producer gas) from gasification of sewage sludge. The cycle is equipped with a spray-ejector condenser (SEC). CO2 is separated and compressed for transportation and storage. The net delivered electric power is 31% of the fuel exergy. The task efficiency is 39% when the flue gas bleed to gasification and O2 penalty are subtracted from fuel, and CO2 capture is included in the useful product. The large part of exergy destruction, 80%, pertains to the combustor. Increasing the temperature or the pressure of the combustor outlet (turbine inlet) lead, as expected, to reduced exergy destruction and more power delivery. Reducing pressure of the gas turbine outlet (SEC inlet) also increases power production. Varying pressure and temperature of the SEC outlet affects the distribution of exergy destruction among units of the condenser, however scarcely the overall efficiency. Reducing the ambient temperature, including cooling water temperature, reduces the efficiency of the plant, contrary to the effect of conventional plants. The reason is that the low pressure of SEC relies on the pressure and mass flow of injected water, rather than the temperature.

  • Exfoliated graphite with spinel oxide as an effective hybrid electrocatalyst for water splitting
    • Malgorzata Skorupska
    • Kinga Kowalska
    • Magdalena Tyc
    • Anna Ilnicka
    • Mariusz Szkoda
    • Jerzy P. Lukaszewicz
    2023 Pełny tekst RSC Advances

    The aim of the conducted research was to develop hybrid nanostructures formed from MnCo2O4 and exfoliated graphite. Carbon added during the synthesis allowed for obtaining a well-distributed MnCo2O4 particle size with exposed active sites contributing to the increased electric conductivity. The influence of the weight ratios of carbon to a catalyst for hydrogen and oxygen evolution reactions was investigated. The new bifunctional catalysts for water splitting were tested in an alkaline medium with excellent electrochemical performance and very good working stability. The results for hybrid samples show better electrochemical performance compared to the pure MnCo2O4. The highest electrocatalytic activity was for sample MnCo2O4/EG (2/1), where the value of the overpotential was 1.66 V at 10 mA cm−2, and also for this sample a low value of Tafel slope (63 mV dec−1) was denoted.

  • Experimental and analytical analysis of punching shear in flat slabs supported on column topped with concrete head
    • Maciej Grabski
    • Andrzej Ambroziak
    2023 CONSTRUCTION AND BUILDING MATERIALS

    An experimental laboraatory test of the two series of slab-column elements topped with drop panels of varying sizes is described in this paper. The scope of the paper is to investigate the influence of the drop panel size and stiffness on the behaviour of the connection between the flat slab and the column topped by the concrete head. The impact of the head size and stiffness is analysed analytically and experimentally. The experimental test results show that at a ratio the heads are too flexible to cause punching shear outside the head, confirm significant concentrations of shear forces at the corners of the large support, and show a significant contribution of the linear parts of the control perimeter to the ultimate force transmitted by the slab-column joint. The authors compare the experimental test results with the considered standard calculation methods and indicate the correlations. The paper provides new experimental results and proposals for the application of a reduction factor for permissible shear stresses in the EC2 standard that depends on the dimension of the support. Simultaneously, the experimental results and the comparison with the standard calculations indicate a further need for research on the connection of a slab to a column topped by a drop panel.

  • Experimental and numerical analysis of the pyrolysis dynamics of a single wood particle: presentation of the radiographic technique
    • Paweł Kazimierski
    • Katarzyna Januszewicz
    • Paulina Hercel
    • Dariusz Kardas
    2023 Pełny tekst WOOD SCIENCE AND TECHNOLOGY

    Pyrolysis is an oxygen-free process for the thermal decomposition of raw materials. The heat conduction and flow of pyrolysis products (i.e., the gas fraction and liquid vapour generated during pyrolysis) influence the process and products. In this work, the influence of the orientation of wooden particle fibres with respect to the direction of the heat source on the dynamics of the process was investigated, where there were two particle sizes oriented along or across the heat source. The novelty of this work lies in the use of a radiographic technique for analysing the influence of wooden fibres' orientation on the degradation process. The research showed that during pyrolysis, the mass loss rate in the particles with fibres oriented across the heat source and along the heat source was different. A similar tendency was characteristic for the drying process. The dynamics of pyrolysis of a single wood particle depends on many factors—particle size, process parameters, arrangement of fibres in wood, etc. The analysis of the dynamics presented in the publications is based on the analysis of the dynamics of mass loss, which is a very large simplification. The publication contains experimental analysis and mathematical calculations of the pyrolysis process for samples of various sizes and samples with different fibre arrangement. The result of the research is the determination of trends regarding the shape of the particle and the arrangement of fibres on the process, which provides knowledge that can be translated into industrial pyrolysis processes.

  • Experimental and numerical investigation of mercury removal from flue gas by sorbent polymer composite
    • Arkadiusz Ryfa
    • Robert Żmuda
    • Sergiusz Mandrela
    • Ryszard Białecki
    • Wojciech Adamczyk
    • Marcin Nowak
    • Łukasz Lelek
    • Dominika Bandoła
    • Marcin Pichura
    • Joanna Płonka
    • Magdalena Wdowin
    2023 Pełny tekst FUEL

    This paper presents an experimental and numerical investigation of the performance of a sorbent polymer composite (SPC) material used for removing mercury from the flue gases in a full-scale industrial installation. The investigated material is an attractive alternative to activated carbon, which is commonly used for this purpose. While the application of the SPC is characterized by high capital expenditures, this technology offers not only very low operating expenditures but also high efficiency. This study investigates the SPC’s mercury reduction capabilities concerning the most important flow parameters such as gas velocity, temperature, humidity, and mercury concentration. Small scale laboratory experiment was used to tune the kinetic data of the mercury adsorption. The resulting sub-model has been built into the CFD simulations validated against measurements at an industrial installation. The results showed that the most important parameters affecting the mercury reduction efficiency were the gas velocity and mercury content in the sorbent material. Numerical simulation proved that the material absorbs mercury within the entire reasonable operating temperature and humidity ranges, regardless of mercury speciation.

  • Experimental and numerical investigation on shell and coil storage unit with biodegradable PCM for modular thermal battery applications
    • Rafał Andrzejczyk
    • Tomasz Muszyński
    • Kowalczyk Tomasz
    • Muhammad Saqib
    2023 INTERNATIONAL JOURNAL OF THERMAL SCIENCES

    Thermal energy storage (TES) in automotive applications is currently growing in importance. TES can visibly reduce primary energy consumptions, decrease CO2 emission, and improve thermal comfort in electric as well as hybrid vehicles. However, to meet the new ambitious target (15% reduction of CO2 emissions in the new cars until 2025) it is required to use plug-in electric vehicles. For this reason, this paper focuses on the optimization of key coil designing parameters. For the reference geometry, both experimental and CFD results have been presented. The optimization of coil geometrical parameters has been carried out based on numerical modelling. The prototype of TES is proposed as a honeycomb battery of individual modules. The results show that increasing the diameter and pitch of the coil decreases the melting and solidification time by 13.2% and 11.8% respectively for chosen geometry. CFD calculation has also been made for TES with a hexagonal geometry. The best results were obtained for the TES with a cylindrical shell. However, the results for the TES with hexagonal shell were, very similar (the difference was less than 1% of the share of the liquid phase). It is seen that presented coil optimization is also a good fit for TES with hexagonal shell geometry.

  • Experimental and Numerical Study on Mechanical Characteristics of Aluminum/Glass Fiber Composite Laminates
    • M. E. Golmakani
    • Tomasz Wiczenbach
    • Mohammad Malikan
    • E. Z. Karimi
    • M. Masoumi
    • Victor Eremeev
    2023 Pełny tekst MECHANICS OF COMPOSITE MATERIALS

    The fiber-metal composites made of aluminum sheets and glass fibers reinforced with a polyester resin as the matrix were studied. The composites were prepared by hand lay-up method. Some aspects of manufacturing affecting the composite behavior were considered. In particular, the influences of the arrangement of layers and their number on the mechanical and physical properties of composites with ten different compositions were investigated. In addition two different densities of glass fibers were considered. The tensile modulus, tensile and impact strengths were determined following ASTM D3039 and ASTM D6110 standards. The results obtained show that the arrangement of the laminate layers influences Young’s modulus and the tensile strength of the composite. The impact test results of the laminated structure reinforced with glass fibers illustrate a significant increase in the impact strength owing to adding the glass fibers compared to the control specimens. The simulations of tests using ABAQUS-based FEA were performed.

  • Experimental certification of more than one bit of quantum randomness in the two inputs and two outputs scenario
    • Alban Jean-Marie Seguinard
    • Amélie Piveteau
    • Piotr Mironowicz
    • Mohamed Bourennane
    2023 Pełny tekst NEW JOURNAL OF PHYSICS

    One of the striking properties of quantum mechanics is the occurrence of the Bell-type non-locality. They are a fundamental feature of the theory that allows two parties that share an entangled quantum system to observe correlations stronger than possible in classical physics. In addition to their theoretical significance, non-local correlations have practical applications, such as device-independent randomness generation, providing private unpredictable numbers even when they are obtained using devices delivered by an untrusted vendor. Thus, determining the quantity of certifiable randomness that can be produced using a specific set of non-local correlations is of significant interest. In this paper, we present an experimental realization of recent Bell-type operators designed to provide private random numbers that are secure against adversaries with quantum resources. We use semi-definite programming to provide lower bounds on the generated randomness in terms of both min-entropy and von Neumann entropy in a device-independent scenario. We compare experimental setups providing Bell violations close to the Tsirelson's bound with lower rates of events, with setups having slightly worse levels of violation but higher event rates. Our results demonstrate the first experiment that certifies close to two bits of randomness from binary measurements of two parties. Apart from single-round certification, we provide an analysis of finite-key protocol for quantum randomness expansion using the Entropy Accumulation theorem and show its advantages compared to existing solutions.

  • Experimental comparison of the transition speed of a hydrodynamic journal bearing lubricated with oil and magnetorheological fluid
    • G.h.g. van der Meer
    • F. Quinci
    • Wojciech Litwin
    • Michał Wodtke
    • R.a.j. van Ostayen
    2023 Pełny tekst TRIBOLOGY INTERNATIONAL

    A journal bearing test bench is used to find the transition speed between the hydrodynamic and mixed lubrication regimes for a modified magnetorheological (MR) fluid. It is shown that the transition speed of the bearing can be reduced by applying a local magnetic field near minimum film when it is lubricated with the MR fluid, and that this will only marginally increase friction. The lubricating performance of the MR fluid is compared to that of a reference oil, and all experimental results are compared with a Finite Element model based on the Reynolds equation.

  • Experimental Evaluation of ND: YAG Laser Parameters and Sample Preparation Methods for Texturing Thin AISI 316L Steel Samples
    • Ewa Kozłowska
    • Sylwia Grabska-Zielińska
    2023 Pełny tekst Applied Sciences-Basel

    In mechanical and material engineering, the effect of laser texturing depends on many factors besides device specification, primarily the properties of the materials being processed, and, secondly, the preparation of the sample. Laser texturing of thin (<5 mm) samples is mostly performed utilizing short-pulse lasers, but depending on the power of the laser beam, the process can also be performed by using continuous operation lasers. When using a laser beam to modify the surface layer, special attention should be paid to the surface preparation process. Engraving a shiny metal surface can lead to laser beam dispersion and energy loss. Some materials require special preparation and surface darkening in order to be effectively engraved. In the case of engraving, maximizing the efficiency and repeatability of the process is the key to obtaining the desired properties. The aim of the conducted study was to establish satisfying parameters and a sample preparation method for texturing thin AISI 316L samples. Appropriately selected laser parameters added to proper sample preparation. The sanding, etching, and darkening of the surface layer improved the quality of the weld and eliminated problems such as deformation and spark formation that often occur with raw samples during the texturing process.

  • Experimental Investigation of the Performance of an Innovative Implantable Left Ventricular Assist Device—Proof of Concept
    • Krzysztof Tesch
    • Ryszard Jasiński
    • Leszek Dąbrowski
    • Jan Rogowski
    2023 Pełny tekst Applied Sciences-Basel

    This paper presents the results of experimental performance of an innovative left ventricular assist device working on a specially designed test stand. The introduced invention is mainly applied for supporting the heart in patients with end-stage heart failure accompanied by mitral valve regurgitation and pulmonary hypertension. Moreover, the developed device has the form of a flexible balloon forming an intracardiac inert gas-filled working chamber, which is divided into two smaller balloons (valve and ventricular) inflated with gas during use. In addition to supporting the heart, replacing the work of the left ventricle in a permanent manner is also possible. Furthermore, the designed test stand makes it possible to carry out realistic experiments in an environment resembling a human heart. Exemplary pressure measurements for hypotension and hypertension conditions are presented.

  • Experimental Investigations of Forced Convection of Nanofluids in Smooth, Horizontal, Round Tubes: A Review
    • Janusz Cieśliński
    • Przemysław Kozak
    2023 Pełny tekst ENERGIES

    A comprehensive review of published works dealing with experimental studies of forced convection heat transfer of nanofluids is presented. The survey is limited to straight, smooth, and round tubes. Moreover, only mono nanofluids exhibiting Newtonian behaviour are considered. Works on experimental research of forced convection in tubes are presented in a chronological order in the first part of the article. In this part, attention was paid to the influence of nanoparticles on the intensification of heat transfer. Information on the tested nanofluids, the measurement technique used, and the measurement range are presented in tabular form. Correlation equations proposed by individual researchers are also presented. In order to explain the controversy regarding the different influences of nanoparticles on the intensity of heat transfer during forced convection of nanofluids, the second part of the paper presents a comparison of the test results obtained by different researchers for the same nanofluid, possibly under the same thermal and flow conditions. Finally, the main conclusions are discussed.

  • Experimental investigations on the mechanical properties and damage detection of carbon nanotubes modified crumb rubber concrete
    • Suliman Khan
    • Shahzad Ashraf
    • Shehroze Ali
    • Khushal Khan
    2023 Pełny tekst Journal of Building Engineering

    This study presents a modified crumb rubber (MCR) concrete design mix reinforced with multi-walled carbon nanotubes (MWCNTs), mechanical characterization, and cracking monitoring using the acoustic emission (AE) technique. The results showed that the bridging effect of MWCNTs and MCR in the concrete mix mitigated the shortcomings of MWCNT-MCR concrete and improved the flexural and compressive strengths by 18.3% and 26.5%, respectively, at 28 days. The stress-strain behavior of the MWCNT-MCR concrete showed improved ductility (48.12%), axial strain (50.12%), and toughness (27.15%) compared to the reference specimens. The MWCNT–MCR concrete exhibited a mechanical response in three distinct loading phases. Overall, tensile failure (>4000 μs/v and >35 kHz) was observed in the tested specimens through the RA value (ratio of rise time to amplitude of AE waves) and average frequency (AF) distribution. Based on the amplitude distribution of the AE waves, the damping capacity of the MWCNT-MCR concrete was improved by 27.83%, and the fracture mechanism between micro and macro cracks was identified through a b-value approach. Finally, a regression model was established to predict the Ec of MWCNT-MCR concrete and the two-way interaction effect on the mechanical properties of the developed mix design.

  • Experimental review of the performances of protective coatings for interconnects in solid oxide fuel cells
    • Mareddy Jayanth Reddy
    • Bartosz Kamecki
    • Belma Talic
    • Elisa Zanchi
    • Federico Smeacetto
    • John S. Hardy
    • Jung Choi Choi
    • Łukasz Mazur
    • Robert Vaßen
    • Soumendra N. Basu
    • Tomasz Brylewski
    • Jan-Erik Svensson
    • Jan Froitzheim
    2023 Pełny tekst JOURNAL OF POWER SOURCES

    Ferritic stainless steel interconnects are used in solid oxide fuel cells; however, coatings are required to improve their performance. Although several types of coatings have been proposed, they have been scarcely investigated under similar conditions. This study compares the characteristics of uncoated Crofer 22 APU and eight different coatings on Crofer 22 APU for up to 3000 h at 800 ◦C. The coatings were deposited at various research laboratories around the world, and the experiments were performed at Chalmers University of Technology, Sweden. Cross-sections of the samples were analysed using scanning electron microscopy and energy-dispersive x-ray spectroscopy. The (Co,Mn)-based coated steels showed more than 50-fold lower chromium evaporation and at least 3 times thinner Cr2O3 scale thickness compared to uncoated steel. The coated steel samples showed lower area-specific resistance (ASR) values than the uncoated steel after 3000 h of exposure, irrespective of the coating thickness, composition and deposition method.

  • Experimental study and numerical simulation of the dynamic penetration into dry clay
    • Victor Eremeev
    • V Balandin
    • Vl Balandin
    • Anatoly Bragov
    • Alexander Konstantinov
    • Leonid Igumnov
    2023 Pełny tekst CONTINUUM MECHANICS AND THERMODYNAMICS

    Tests of dry clay were carried out in a uniaxial stress state using the experimental setup which implements the split Hopkinson pressure bar method. Based on the results of these experiments, the compressive strength of clay was determined as an important element of S.S. Grigoryan’s model of the soil medium. In addition, the parameters of this model are determined from the results of experiments using the modified Kolsky method with a sample enclosed in a rigid cage. To verify the model of the soil medium, special experiments were carried out on the penetration of striker with conical tips into dry clay in a reversed settings. Using this identified model in the LS-Dyna software package, numerical simulation of penetration into clay was carried out under conditions similar to those carried out the reversed experiments. Comparison of the results of physical and numerical experiments showed their satisfactory agreement at a dry friction coefficient of 0.5.

  • Experimental study of flow boiling pressure drop and heat transfer of R1233zd(E) at moderate and high saturation temperatures
    • Michał Pysz
    • Stanisław Głuch
    • Dariusz Mikielewicz
    2023 Pełny tekst INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER

    The paper presents the results of experimental study of flow boiling of R1233zd(E) in minichannel at moderate and high saturation temperatures. The heat transfer coefficient and pressure drop were measured for flow boiling in a stainless steel tube with 2 mm inside diameter and a length of 300 mm. Experiment has been conducted for saturation temperatures ranging from 83 to 145 °C which corresponds to values of reduced pressures ranging from 0.2 to 0.7. Three different heat fluxes were analyzed, namely 20, 30 and 45 kW/m2 and mass velocities ranged from 200 to 1000 kg/m2s. The effects of reduced pressure, mass velocity, heat flux, vapor quality and flow regime were analyzed. At low reduced pressures (pr≤ 0.3) heat transfer is driven by convective boiling mostly with nucleate boiling having effect only in the case of low mass velocities. Heat transfer in this case increases with mass velocity and vapor quality and is independent of heat flux. For reduced pressures of 0.4 and 0.5 both nucleate and convective boiling are present, however the nucleate boiling starts to be more dominant here, especially for low mass velocities and high heat fluxes. For low mass velocities and/or higher heat fluxes the heat transfer decrease or is independent of vapor quality, whereas for higher mass fluxes and/or lower heat fluxes it is initially independent of vapor quality and starts to increase close to the transition from intermittent to annular flow. At the range of high reduced pressures (pr ≥ 0.6) nucleate boiling is the dominant heat transfer mechanism. Experimental results were compared with some well-known two-phase flow correlations.

  • Experimental Study of Flow Rate in Hydraulic Satellite Motor with the Rotating Case at a Low Constant Rotational Speed
    • Paweł Śliwiński
    • Piotr Patrosz
    • Marcin Bąk
    • Michał Stosiak
    • Kamil Urbanowicz
    • Šarūnas Šukevičius
    2023

    In this article was described the methodology for the experimental study of flows in the prototype of a satellite hydraulic motor with a rotating body. The experimental tests of the motor were carried out at a low constant rotational speed in a wide range of pressure drop in this motor. The constant rotational speed of the motor was kept by a worm gear. Based on the test results, the leakage characteristics in the flat gaps of the curvature, satellites and in the commutation unit gaps were determined. The test results also allowed to evaluate the correct operation of the commutation unit and the compensation unit of axial clearances of the curvature and satellites in the working mechanism of the motor.

  • Experimental Study of Polish Sausage Drying Kinetics and Contraction by Image Data Analysis
    • Blanka Jakubowska
    2023 Pełny tekst Acta Universitatis Cibiniensis - Series E: Food Technology

    The goal of this paper has been to add an experimental data set for drying a meat product and provide a comparison with well-established thin-layer drying models. This article presented experimental investigations on the convective drying of Polish sausage slices at a temperature of 40°C. Slices have been in the thickness of 3 to 8mm. Measurements of mass loss and size change were performed. The data have been presented in the form of standard drying kinetics. Additionally, the estimation of the diffusion coefficient according to the simplified graphical approach is made. Based on the best-fit approach the coefficients for typical semiempirical correlations for MR (moisture ratio) estimation have been calculated and presented.

  • Experimental study on earthquake-induced pounding between steel structures
    • Barbara Sołtysik
    • Robert Jankowski
    2023 ce/papers

    Pounding between adjacent structures has been repeatedly observed during major earthquakes. The phenomenon may cause some local damage at the points of interactions, it may also lead to substantial destruction, permanent deformations or total collapse of colliding structures. The effects of earthquake-induced structural pounding have been studied for more than three decades now. However, most of the studies concerned masonry as well as reinforced concrete structures and investigations on steel structures are very limited. The aim of the present paper is to show the results of the shaking table experimental investigation focused on earthquake-induced pounding between three models of steel structures in a row. The models were constructed out of four steel columns made from rectangular box section with additional steel skew bracings so as to prevent transverse and torsional vibrations. To obtain different dynamic characteristics of the models, additional plates were added at the top of each tower. Two configurations were investigated. In the first one, two plates were mounted on the external structures and only one plate at the top of the middle tower. In the second configuration, only one plate was mounted at the top of external towers and two plates on the middle structure. Firstly, the free vibration tests were conducted. Then, the steel towers with different in-between gap sizes were tested under different earthquakes. The results of the study confirm that interactions between insufficiently separated steel structures may significantly influence the structural behaviour during earthquakes. In most of the cases, pounding has resulted in the increase in the peak responses. In some cases, however, it has played a positive role leading to the decrease in the structural response under seismic excitation. Anyway, even if the response is reduced, interactions should be prevented at the design stage of steel structures since they may result in considerable damage at the points of impacts.

  • Experimental study on the effect of selected sterilization methods on mechanical properties of polylactide FFF specimens
    • Angela Andrzejewska
    2023 Pełny tekst RAPID PROTOTYPING JOURNAL

    Purpose: Biodegradable polymers are widely used in personalized medical devices or scaffolds for tissue engineering. The manufacturing process should be finished with sterilization procedure. However, it is not clear how the different sterilization methods have an impact on the mechanical strength of the three-dimensional (3D)-printed parts, such as bone models or personalized mechanical devices. This paper aims to present the results of mechanical testing of polylactide-based bone models before and after sterilization. Design/methodology/approach: Polylactide specimens prepared in fused filament fabrication technology were sterilized with different sterilization methods: ultraviolet (UV) and ethylene oxide. Mechanical properties were determined by testing tensile strength, Young’s modulus and toughness. Findings: The tensile strength of material after sterilization was significantly higher after ethylene oxide sterilization compared to the UV sterilization, but in both sterilization methods, the specimens characterized lower tensile strength and Young’s modulus when compared to the control. In comparison of toughness results, there was no statistically significant differences. The findings are particularly significant in the perspective of using individual implants, bone grafts and dental guides. Originality/value: Although fused filament fabrication (FFF) 3D printing devices equipped with UV light sterilization options are available, experimental results of the effect of selected sterilization methods on the mechanical strength of additively manufactured parts have not been described. This paper completes the present state of the art on the problem of sterilization of FFF parts from biodegradable materials.

  • Experimental ultimate strength assessment of stiffened plates subjected to marine immersed corrosion
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    • Jakub Kowalski
    2023 Pełny tekst APPLIED OCEAN RESEARCH

    This study experimentally analyses the impact of marine immersed corrosion degradation on the compressive strength of the stiffened plates where the lower degradation levels were considered. The corrosion degradation test was accelerated by controlling the natural corrosion environmental factors, avoiding applying an electric current. Different groups of corrosion degradation levels and initial plate thicknesses were investigated. The specimens were subjected to a compressive load via a universal testing machine. The estimated force-displacement relationships and lateral displacements as a function of the degree of degradation were analysed. Several analyses and discussions showed that considering only the mean value of the corrosion thickness loss, it is insufficient to evaluate the stiffened plates' ultimate strength correctly, and the type of corrosion degradation needs to be accounted for appropriately.

  • Experimental Verification of the CFD Model of the Squeeze Film Lifting Effect
    • Bartosz Bastian
    • Rafał Gawarkiewicz
    • Michał Wasilczuk
    • Michał Wodtke
    2023 Pełny tekst Applied Sciences-Basel

    Abstract: The presented study shows the results of the research into the squeeze film levitation phenomena. The system introduced in the investigation is composed of a vibrating surface, air squeeze film, and the surface of the body freely suspended over the film. The use of the CFD (Computational Fluid Dynamics) model used in the system allows us to determine the steady state, periodic behavior of the air film (described by Navier–Stokes, continuity equations, and ideal gas law), and the lifted object dynamics. The model allows us to determine multiple factors, among others, mean film thickness and pressure distribution inside the fluid film. The influence of factors, such as vibration amplitude, frequency, and load on the lifting conditions, was presented. A series of calculations show the levitations height in the range of 5.61 up to 58.12 microns, obtained for masses of samples between 5–20 g, vibration frequency of 5–25 kHz, and the motions amplitude of 0.5–1.5 m. A series of CFD multivariable calculations for a standing wave inducer were not previously published. The CFD model was validated with the use of experiments on a specially developed test rig. The authors experimentally obtained the height of levitation up to 200 microns.