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  • Measuring Tilt with an IMU Using the Taylor Algorithm
    • Jerzy Demkowicz
    2024 Remote Sensing

    This article addresses the important problem of tilt measurement and stabilization. This is particularly important in the case of drone stabilization and navigation in underwater environments, multibeam sonar mapping, aerial photogrammetry in densely urbanized areas, etc. The tilt measurement process involves the fusion of information from at least two different sensors. Inertial sensors (IMUs) are unique in this context because they are both autonomous and passive at the same time and are therefore very attractive. Their calibration and systematic errors or bias are known problems, briefly discussed in the article due to their importance, and are relatively simple to solve. However, problems related to the accumulation of these errors over time and their autonomous and dynamic correction remain. This article proposes a solution to the problem of IMU tilt calibration, i.e., the pitch and roll and the accelerometer bias correction in dynamic conditions, and presents the process of calculating these parameters based on combined accelerometer and gyroscope records using a new approach based on measuring increments or differences in tilt measurement. Verification was performed by simulation under typical conditions and for many different inertial units, i.e., IMU devices, which brings the proposed method closer to the real application context. The article also addresses, to some extent, the issue of navigation, especially in the context of dead reckoning.

  • Mechanical Properties of 3D Printed Parts and Their Injection Molded Alternatives Subjected to Environmental Aging
    • Angela Jadwiga Andrzejewska
    2024 3D Printing and Additive Manufacturing

    Additive manufacturing is the technology used in medical, industrial, or lifestyle applications. The scientific literature include works reporting various manufacturing parameters’ influence on changes in additive manufacturing components’ mechanical behavior, especially with fused filament fabrication (FFF). The changes in mechanical strength and toughness of FFF compared to injection molding parts were studied. In the study, the FFF and injection molded parts were aged in buffered saline solution in temperature of 37C. The results show that by differentiating the orientation of the fibers during fabricating, it is possible to reach strength values similar to injection molded parts. Therefore, it was reported that the mechanical strength and toughness changed significantly after aging, and the FFF components lost strength more quickly than their injected alternatives. The research results can be useful during the fabrication of mechanically stable and biodegradable components, which can be more easily recycled than their injected alternatives when used with warmer temperatures and humidity. This article completes the present state of the art on the problem of environmental aging of parts produced from biodegradable materials. Especially, the research was related to the multilayer laminate structure.

  • Mechanical Properties of Additively Manufactured Polymeric Materials—PLA and PETG—For Biomechanical Applications
    • Rui F. Martins
    • Ricardo Branco
    • Miguel Martins
    • Wojciech Macek
    • Zbigniew Marciniak
    • Rui Silva
    • Daniela Trindade
    • Carla Moura
    • Margarida Franco
    • Cândida Malça
    2024 Pełny tekst Polymers

    The study presented herein concerns the mechanical properties of two common polymers for potential biomedical applications, PLA and PETG, processed through fused filament fabrication (FFF)—Material Extrusion (ME). For the uniaxial tension tests carried out, two printing orientations—XY (Horizontal, H) and YZ (Vertical, V)—were considered according to the general principles for part positioning, coordinates, and orientation typically used in additive manufacturing (AM). In addition, six specimens were tested for each printing orientation and material, providing insights into mechanical properties such as Tensile Strength, Young’s Modulus, and Ultimate Strain, suggesting the materials’ potential for biomedical applications. The experimental results were then compared with correspondent mechanical properties obtained from the literature for other polymers like ASA, PC, PP, ULTEM 9085, Copolyester, and Nylon. Thereafter, fatigue resistance curves (S-N curves) for PLA and PETG, printed along 45°, were determined at room temperature for a load ratio, R, of 0.2. Scanning electron microscope observations revealed fibre arrangements, compression/adhesion between layers, and fracture zones, shedding light on the failure mechanisms involved in the fatigue crack propagation of such materials and giving design reference values for future applications. In addition, fractographic analyses of the fatigue fracture surfaces were carried out, as well as X-ray Computed Tomography (XCT) and Thermogravimetric (TGA)/Differential Scanning Calorimetric (DSC) tests.

  • Mechanical response of human thoracic spine ligaments under quasi-static loading: An experimental study
    • Radosław Wolny
    • Tomasz Wiczenbach
    • Angela Andrzejewska
    • Jan Henryk Spodnik
    2024 Journal of the Mechanical Behavior of Biomedical Materials

    Purpose This study aimed to investigate the geometrical and mechanical properties of human thoracic spine ligaments subjected to uniaxial quasi-static tensile test. Methods Four human thoracic spines, obtained through a body donation program, were utilized for the study. The anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), capsular ligament (CL), ligamenta flava (LF), and the interspinous ligament and supraspinous ligament complex (ISL + SSL), were investigated. The samples underwent specimen preparation, including dissection, cleaning, and reinforcement, before being immersed in epoxy resin. Uniaxial tensile tests were performed using a custom-designed mechanical testing machine equipped with an environmental chamber (T = 36.6 °C; humidity 95%). Then, the obtained tensile curves were averaged preserving the characteristic regions of typical ligaments response. Results Geometrical and mechanical properties, such as initial length and width, failure load, and failure elongation, were measured. Analysis of variance (ANOVA) revealed significant differences among the ligaments for all investigated parameters. Pairwise comparisons using Tukey's post-hoc test indicated differences in initial length and width. ALL and PLL exhibited higher failure forces compared to CL and LF. ALL and ISL + SSL demonstrated biggest failure elongation. Comparisons with other studies showed variations in initial length, failure force, and failure elongation across different ligaments. The subsystem (Th1 – Th6 and Th7 – Th12) analysis revealed increases in initial length, width, failure force, and elongation for certain ligaments. Conclusions Variations of both the geometric and mechanical properties of the ligaments were noticed, highlighting their unique characteristics and response to tensile force. Presented results extend very limited experimental data base of thoracic spine ligaments existing in the literature. The obtained geometrical and mechanical properties can help in the development of more precise human body models (HBMs).

  • Mechanisms of Li deposition on graphite anodes: surface coverage and cluster growth
    • Arihant Bhandari
    • Jacek Dziedzic
    • John R. Owen
    • Denis Kramer
    • Chris-Kriton Skylaris
    2024 Pełny tekst Journal of Materials Chemistry A

    Li plating on the anode is a side reaction in Li-ion batteries which competes with Li intercalation and leads to loss of capacity. Growth of Li clusters into dendrites is a potential safety hazard for batteries which can lead to internal short-circuit and fires. We consider two possibilities of Li deposition on the surface of graphite anode: deposition of Li+ ions uniformly on the surface and deposition of clusters of metallic Li. Using ab initio simulations, we predict the operating voltage for the occurrence of the above processes and safety measures to prevent dendrite growth in batteries. We find that Li deposition occurs in the following stages: at positive voltages vs. Li, surface deposition of Li+ ions is the dominant process. Below a critical cross-over voltage, the process of reduction of aggregated Li+ ions and the formation of metallic Li clusters takes over. This cross-over voltage is found to be −12 mV on the basal plane of unlithiated graphite and −29 mV on lithiated graphite. To prevent formation of Li clusters and for safe operation of Li-ion batteries, the voltage on the graphite anode should be kept above the cross-over value.

  • Melanoma skin cancer detection using mask-RCNN with modified GRU model
    • K. M. Monica
    • J. Shreeharsha
    • Przemysław Falkowski-Gilski
    • Bożena Falkowska-Gilska
    • Mohan Awasthy
    • Rekha Phadk
    2024 Pełny tekst Frontiers in Physiology

    Introduction: Melanoma Skin Cancer (MSC) is a type of cancer in the human body; therefore, early disease diagnosis is essential for reducing the mortality rate. However, dermoscopic image analysis poses challenges due to factors such as color illumination, light reflections, and the varying sizes and shapes of lesions. To overcome these challenges, an automated framework is proposed in this manuscript. Methods: Initially, dermoscopic images are acquired from two online benchmark datasets: International Skin Imaging Collaboration (ISIC) 2020 and Human against Machine (HAM) 10000. Subsequently, a normalization technique is employed on the dermoscopic images to decrease noise impact, outliers, and variations in the pixels. Furthermore, cancerous regions in the pre-processed images are segmented utilizing the mask-faster Region based Convolutional Neural Network (RCNN) model. The mask-RCNN model offers precise pixellevel segmentation by accurately delineating object boundaries. From the partitioned cancerous regions, discriminative feature vectors are extracted by applying three pre-trained CNN models, namely ResNeXt101, Xception, and InceptionV3. These feature vectors are passed into the modified Gated Recurrent Unit (GRU) model for MSC classification. In the modified GRU model, a swish-Rectified Linear Unit (ReLU) activation function is incorporated that efficiently stabilizes the learning process with better convergence rate during training. Results and discussion: The empirical investigation demonstrate that the modified GRU model attained an accuracy of 99.95% and 99.98% on the ISIC 2020 and HAM 10000 datasets, where the obtained results surpass the conventional detection models.

  • Meldrum’s acid assisted formation of tetrahydroquinolin‑2‑one derivatives a short synthetic pathway to the biologically useful scaffold
    • Małgorzata Ryczkowska
    • Alicja Trocka
    • Anna Hromova
    • Sławomir Makowiec
    2024 Pełny tekst Scientific Reports

    A new method for the preparation of tetrahydroquinolin-2-one derivatives is presented. This approach involves a two-step reaction between enaminones and acylating agents, immediately followed by electrophilic cyclization, all within a single synthesis procedure, eliminating the need to isolate intermediates. The entire process is facilitated by the use of acyl Meldrum’s acids which not only shortens the preparation time of the substrates but also easily extends the range of substituents That can be used. The method’s scope and limitations were evaluated with various reagent combinations thus demonstrating its general applicability to the synthesis of tetrahydroquinolin-2-one core. Interestingly, some exceptions to the regular reaction pathway were observed when a strong EDG (electron donating group) was introduced via acyl Meldrum’s acids. The underlying mechanism of this phenomenon was elucidated during the investigation.

  • MEMS Modeling in the Context of Inertial Navigation
    • Jerzy Demkowicz
    2024 International Journal of Electronics and Telecommunications

    Underwater navigation is a research topic current undertaken in many areas of underwater research. The article presents an analysis resulting from MEMS modelling in the context of inertial navigation. The ideal approach was confronted with its limitations, but a non-linear approach, close to the real one, was also presented. Both models were compared in the context of inertial navigation. Random disturbances and their impact on linear and nonlinear dynamic systems, and in this context on Brownian noise motion, were also analysed. The linear velocity and displacement estimates generated by the presented models were compared to the ideal responses. The phenomenon of bifurcation in the context of inertial measurements is presented. Some of the analysis is performed on real data, but for greater clarity, some is performed on simulated data to highlight design issues and limitations.

  • Merton-type default risk and financial performance: the dynamic panel moderation of firm size
    • Muhammad Mushafiq
    • Syed Ahmad Sami
    • Muhammad Khalid Sohail
    • Muzammal Ilyas Sindhu
    2024 Journal of Economic and Administrative Sciences

    Purpose – The main purpose of this study is to evaluate the probability of default and examine the relationship between default risk and financial performance, with dynamic panel moderation of firm size. Design/methodology/approach – This study utilizes a total of 1,500 firm-year observations from 2013 to 2018 using dynamic panel data approach of generalized method of moments to test the relationship between default risk and financial performance with the moderation effect of the firm size. Findings – This study establishes the findings that default risk significantly impacts the financial performance. The relationship between distance-to-default (DD) and financial performance is positive, which means the relationship of the independent and dependent variable is inverse. Moreover, this study finds that the firm size is a significant positive moderator between DD and financial performance. Practical implications – This study provides new and useful insight into the literature on the relationship between default risk and financial performance. The results of this study provide investors and businesses related to nonfinancial firms in the Pakistan Stock Exchange (PSX) with significant default risk’s impact on performance. This study finds, on average, the default probability in KSE ALL indexed companies is 6.12%. Originality/value – The evidence of the default risk and financial performance on samples of nonfinancial firms has been minimal; mainly, it has been limited to the banking sector. Moreover, the existing studies have only catered the direct effect of only. This study fills that gap and evaluates this relationship in nonfinancial firms. This study also helps in the evaluation of Merton model’s performance in the nonfinancial firms.

  • Mesoscopic simulations of a fracture process in reinforced concrete beam in bending using a 2D coupled DEM/micro-CT approach
    • Michał Nitka
    • Andrzej Tejchman-Konarzewski
    2024 Pełny tekst ENGINEERING FRACTURE MECHANICS

    W tej pracy zbadano numerycznie w warunkach 2D złożony proces pękania w krótkiej prostokątnej belce betonowej wzmocnionej jednym prętem podłużnym (bez zbrojenia pionowego) i poddanej quasi-statycznemu zginaniu w trzech punktach. Krytyczne pęknięcie poprzeczne w belce spowodowało jej uszkodzenie podczas doświadczenia. Symulacje numeryczne przeprowadzono klasyczną metodą elementów dyskretnych (DEM). Przyjęto trójfazowy opis betonu: kruszywa, zaprawa i międzyfazowe strefy przejściowe (ITZ) wokół kruszyw. W mezoskopowych obliczeniach DEM opartych na skanach rentgenowskich CT 2D przyjęto rzeczywisty kształt i połączenie cząstek kruszywa w betonie. W obliczeniach odtworzono pręt stalowy z żebrami. Założono także ITZ pomiędzy prętem a zaprawą. Bez narzucania prawa poślizgu, uwzględniono warunek geometryczny na granicy pręt/beton. W pracy skupiono się na wykresie siła-ugięcia, procesie pękania, siłach kontaktowych i naprężeniach wzdłuż pręta. Uzyskano dobry poziom zgodności ewolucji siły pionowej w zależności od ugięcia i mechanizmu zniszczenia w analizach DEM w porównaniu z testami laboratoryjnymi pomimo przyjęcia uproszczonych warunków 2D. Wykazano silny wpływ mezostruktury betonu na wzór pęknięcia.

  • Method for prediction of the frost resistance ability of air‐entrained concrete based on the 3D air void characteristics by x‐ray micro‐CT
    • Łukasz Skarżyński
    • Mikołaj Miśkiewicz
    2024 Structural Concrete

    In modern construction, one of the most important factors in the execution of contracts is time. Standard procedures for assessing the frost resistance or concrete are usually very time-consuming and can take up to 40 days. The current paper is experimentally and practically oriented. It presents an alternative testing method, based on air void network, that allows to assess the frost resistance of concrete within just a few days of taking the samples. X-ray micro-CT scans were introduced to obtain the quantitative and qualitative 3D information about the air void microstructure taking into account total air content: A [%], pores of the size below 300 μm in diameter content: A300 [%], specific surface of air voids: α [mm-1] and spacing factor: L [mm] in order to predict the freeze / thaw durability. To verify the assumptions of the frost resistance method, based on the analysis of pore microstructure, tests of freeze / thaw resistance in accordance with Polish supplement to European Standard [46] were carried out. Presented research revealed that the appropriate microstructure of air pores, in particular, content of micropores with the diameter less than 0.3 mm: A300 combined with a spacing factor: L [mm] can constitute a reliable basis for determining concrete freeze / thaw durability. Thus, method proposed in current paper can be effectively used for fast and trustworthy determination of the air-entrained concrete durability in a short time and without any special preparation of the tested sample, that allows immediate preventive or repair actions to be taken if required.

  • Method of Forming Road Surface Replicas Using 3D Printing Technology
    • Wojciech Owczarzak
    • Sławomir Sommer
    • Grzegorz Ronowski
    2024 Coatings

    Rolling resistance is a critical factor that influences vehicle energy consumption, emissions, and overall performance. It directly impacts fuel efficiency, tire longevity, and driving dynamics. Traditional rolling resistance tests are conducted on smooth steel drums, which fail to replicate real-world road surface textures, potentially skewing results. This article presents the process of designing surface replicas using 3D printing technology, which consisted of selecting the internal structure, material, and print parameters of the surface sample. In order to verify the designed structures, an original mechanical strength test was performed. The test was based on pressing the tire onto the test sample with an appropriate force that corresponded to typical conditions during rolling resistance measurements. The test results included surface texture profiles before and after the application of load, which were then superimposed to detect any possible sample deformation. The obtained strength test results confirmed the validity of using 3D printing technology in the process of obtaining road surface replicas.

  • Methodology Approach for Microplastics Isolation from Samples Containing Sucrose
    • Kornelia Kadac-Czapska
    • Beata Bochentyn
    • Aleksandra Maślarz
    • Sebastian Mahlik
    • Małgorzata Grembecka
    2024 MOLECULES

    The growing production and use of plastics significantly contribute to microplastics (MPs) contamination in the environment. Humans are exposed to MPs primarily through the gastrointestinal route, as these particles are present in beverages and food, e.g., sugar. Effective isolation and identification of MPs from food is essential for their elimination. This study aimed to evaluate factors influencing the isolation of MPs from sucrose solutions to determine optimal conditions for the process. Polyethylene particles were used to test separation methods involving chemical digestion with acids and filtration through membrane filters made of nylon, mixed cellulose ester, and cellulose acetate with pore sizes of 0.8 and 10 µm. The effects of temperature and acid type and its concentration on plastic particles were examined using scanning electron microscopy and µ-Raman spectroscopy. The results indicate that increased temperature reduces solution viscosity and sucrose adherence to MPs’ particles, while higher acid concentrations accelerate sucrose hydrolysis. The optimal conditions for MPs’ isolation were found to be 5% HCl at 70 ◦C for 5 min, followed by filtration using an efficient membrane system. These conditions ensure a high recovery and fast filtration without altering MPs’ surface properties, providing a reliable basis for further analysis of MPs in food.

  • Methodology of generation of CFD meshes and 4D shape reconstruction of coronary arteries from patient-specific dynamic CT
    • Krzysztof Psiuk-Maksymowicz
    • Damian Borys
    • Bartlomiej Melka
    • Maria Gracka
    • Wojciech Adamczyk
    • Marek Rojczyk
    • Jaroslaw Wasilewski
    • Jan Głowacki
    • Mariusz Kruk
    • Marcin Nowak
    • Ziemowit Ostrowski
    • Ryszard Bialecki
    2024 Pełny tekst Scientific Reports

    Due to the difficulties in retrieving both the time‑dependent shapes of the vessels and the generation of numerical meshes for such cases, most of the simulations of blood flow in the cardiac arteries use static geometry. The article describes a methodology for generating a sequence of time‑dependent 3D shapes based on images of different resolutions and qualities acquired from ECG‑gated coronary artery CT angiography. The precision of the shape restoration method has been validated using an independent technique. The original proposed approach also generates for each of the retrieved vessel shapes a numerical mesh of the same topology (connectivity matrix), greatly simplifying the CFD blood flow simulations. This feature is of significant importance in practical CFD simulations, as it gives the possibility of using the mesh‑morphing utility, minimizing the computation time and the need of interpolation between boundary meshes at subsequent time instants. The developed technique can be applied to generate numerical meshes in arteries and other organs whose shapes change over time. It is applicable to medical images produced by other than angio‑CT modalities.

  • Methods for Quality Assessment of Window View
    • Barbara Matusiak
    • Filomena Russo
    • Mandana Khanie, Sarey
    • Natalia Sokół
    • Christina Hemauer
    • Klaus Martiny
    • Carlo Volf
    • Siegrun Appelt
    • Natalia Giraldo Vasquez
    • Aicha Diakite-Kortlever
    2024 Pełny tekst Land

    This paper summarises findings from two workshops evaluating a series of views in various settings by an interdisciplinary group of experts. In the first one (Trondheim, June 2022), ten experts visited and assessed views from nine rooms. In the second one (Lausanne, June 2023), eleven experts assessed window views from four spaces. The workshops’ main objective was to develop and test multi-method assessments of window views. During both workshops, participants completed a survey that included close and open-ended questions about the perceived quality of the room and the view. Participants also measured lux level, took photographs, made hand drawings of the view, and answered a questionnaire about their mood and the environmental conditions in the room. After the workshop, point-in-time daylight simulations were performed for the visited rooms. The paper describes, compares, and recommends the use of the aforementioned methods depending on the type and complexity of the view, and the space, the evaluators’ professional background, and the type of collected data. It also discusses the overlap of the methods and estimates the preparation time, time spent on site, and the amount of work after the visit. Finally, it recommends the use of the tested methods depending on the application.

  • Miasta Nieskończone. Warsztaty animacji poklatkowej doodle-art. Bałtycki Festiwal Nauki 2024
    • Marta Koperska-Kośmicka
    • Agnieszka Kurkowska
    • Aleksandra Karpińska
    2024

    Warsztaty animacji poklatkowej w technice doodle-art, podczas których uczestnicy stworzyli wspólnie animowany film o mieście marzeń. Warsztaty z animacji poklatkowej są zajęciami rozwijającymi wyobraźnię i kreatywność. Film powstawał zespołowo, poprzez dodawanie nowych elementów rysunku przez każdego z uczestników. Kolejne fazy powstawania wymarzonego miasta zostały uwiecznione na zdjęciach, które po cyfrowej obróbce pozwoliły na stworzenie krótkiego, jednominutowego animowanego filmu.

  • Micro- and nano-Illite to improve strength of untreated-soil as a nano soil-improvement (NSI) technique
    • M Cheraghalikhani,
    • Hamed Niroumand
    • Lech Bałachowski
    2024 Pełny tekst Scientific Reports

    Soil stabilization is a technique of improving the geotechnical properties of soils for various engineering applications. However, conventional stabilizers such as cement and lime have some limitations, such as high cost, environmental impact, and durability issues. Therefore, there is a need for alternative and innovative stabilizers that can overcome these challenges. This study introduces nano-Illite, a type of clay mineral, as a novel and efective soil stabilizer. Nano-Illite can form nano-cementation (NC) in soil, which is a process of enhancing the durability of various building materials. NC is also known as nano soil-improvement (NSI), a technique that has been developed in recent years. Four formulations of micro- and nano-Illite with concentrations of 0, 1, 2, and 3% were separately added to soil samples. The unconfned compressive strength (UCS) and the secant modulus at 50% of peak stress (E50) of the treated samples were measured and compared with the untreated samples. The results showed that 3% nano-Illite increased the UCS of soil by more than 2.2 times and the E50 by more than 1.5 times after 7 days of curing. Micro-Illite also improved the UCS and E50 of soil, but to a lesser extent. X-ray fuorescence (XRF), scanning electron microscopy (SEM), and X-ray difraction (XRD) analyses revealed the micro- and nano-structures of the soil specimens and the performance of Illite as a nano-additive. This research demonstrates the efectiveness of nano-Illite in soil improvement as a NSI technique, and its potential to replace or reduce the use of conventional stabilizers. This study also contributes to the understanding of the mechanisms and factors that infuence the NC process in soil.

  • Microbe Cultivation Guidelines to Optimize Rhamnolipid Applications
    • Ilona Kłosowska-Chomiczewska
    • Adam Macierzanka
    • Karol Parchem
    • Pamela Miłosz
    • Sonia Sarach
    • Iga Płaczkowska
    • Weronika Hewelt-Belka
    • Christian Jungnickel
    2024 Pełny tekst Scientific Reports

    In the growing landscape of interest in natural surfactants, selecting the appropriate one for specific applications remains challenging. The extensive, yet often unsystematized, knowledge of microbial surfactants, predominantly represented by rhamnolipids (RLs), typically does not translate beyond the conditions presented in scientific publications. This limitation stems from the numerous variables and their interdependencies that characterize microbial surfactant production. We hypothesized that a computational recipe for biosynthesizing RLs with targeted applicational properties could be developed from existing literature and experimental data. We amassed literature data on RL biosynthesis and micellar solubilization and augmented it with our experimental results on the solubilization of triglycerides (TGs), a topic underrepresented in current literature. Utilizing this data, we constructed mathematical models that can predict RL characteristics and solubilization efficiency, represented as logPRL = f(carbon and nitrogen source, parameters of biosynthesis) and logMSR = f(solubilizate, rhamnolipid (e.g. logPRL), parameters of solubilization), respectively. The models, characterized by robust R2 values of respectively 0.581-0.997 and 0.804, enabled the ranking of descriptors based on their significance and impact — positive or negative — on the predicted values. These models have been translated into ready-to-use calculators, tools designed to streamline the selection process for identifying a biosurfactant optimally suited for intended applications.

  • Microextraction by packed sorbent: Uncommon detection techniques, sorbents, samples and analytes
    • Vasil Andruch
    • Alina Kalyniukova
    • Tanya Yordanova
    • Justyna Płotka-Wasylka
    • Viera Vojteková
    • Gokhan Zengin
    2024 TRAC-TRENDS IN ANALYTICAL CHEMISTRY

    Among sample preparation approaches, the most desirable are procedures that ensure high efficiency and reproducibility, that are cheap, fast and simple, that minimize the number of operational steps and that require a small amount of sample and solvent and are thus environmentally friendly. Microextraction by packed sorbent (MEPS) is a miniaturized form of solid-phase extraction, the use of which has been continuously expanding since its introduction in 2004. This technique can be considered green, and due to its many advantages, it has been widely accepted and used for sample pretreatment prior to instrumental analysis. This mini-review deals with the presentation and discussion of atypical, less described approaches and solutions with the MEPS technique, especially in regard to the detection techniques and sorbents used, the samples analyzed and the analytes determined. We hope this review will interest, inspire and motivate readers to explore new MEPS applications.

  • Microfluidically Frequency-Reconfigurable Compact Self-Quadruplexing Tunable Antenna with High Isolation Based on Substrate Integrated Waveguide
    • Rusan Kumar Barik
    • Sławomir Kozieł
    2024 Pełny tekst Scientific Reports

    This communication presents a novel concept of microfluidically frequency-reconfigurable self-quadruplexing tunable antenna for quad-band applications. At the initial design stage, a substrate-integrated square cavity is divided into four unequal quarter-mode cavity resonators by inserting an X-shaped slot on the top surface of the cavity. Applying four 50-ohm microstrip feed-lines to these four quarter-mode cavity resonators enables quad-band operation with self-quadruplexing capabilities. The feed lines are organized orthogonally and off-center, which leads to port isolation greater than 32.3 dB. An equivalent network model is developed to validate the proposed antenna. To realize frequency reconfigurability, two microfluidic channels corresponding to each port are created by engraving the bottom surface of the cavity. To create a reconfigurable self-quadruplexing antenna, the channels are either filled with air or dielectric liquids of higher permittivity, so that the design offers independent tunability of the operating frequencies. As a proof of concept, the prototype of a self-quadruplexing tunable antenna is fabricated and validated through measurements. The antenna prototype occupies a footprint area of 0.37λg2. The design exhibits frequency tuning ranges of 350 MHz (8.3%), 500 MHz (10.3%), 610 MHz (11.2%), and 845 MHz (14.1%) for the first, second, third, and fourth operating bands, respectively. In all bands and across the entire tuning range, the realized gains of the designed antenna exceed 4.05 dBi. The electromagnetic modeling responses agree extremely well with the measured characteristics.

  • Microfluidically Frequency-Reconfigurable Self-Quadruplexing Antenna Based on Substrate Integrated Square-Cavity
    • Rusan Kumar Barik
    • Sławomir Kozieł
    2024 AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS

    In this article, a novel concept of self-quadruplexing tunable antenna (SQTA) enabled by microfluidic channels is investigated. The operating channels are either filled with air or dielectric liquids to enable frequency tunability. The proposed SQTA is implemented on the substrate-integrated square-cavity (SISC). A swastika-shaped slot is milled on the top-surface of the SISC to create four quarter-mode resonators. The resonators are excited by four 50-Ω microstrip lines to enable independent operating bands with self-quadruplexing properties. The working principle is validated by a custom-developed lumped-circuit model. The port isolations are better than 27dB due to the orthogonal and off-centered port allocation. Subsequently, two microfluidic channels corresponding to each quarter-mode resonator are milled from bottom-surface of the cavity. These two channels are filled with liquids of various permittivity to achieve frequency tunability. As a proof-of-concept, a prototype of the proposed SQTA is fabricated and demonstrated experimentally. The fabricated SQTA operates at 4.05-4.56 GHz, 4.645-5.295 GHz, 5.45-6.325 GHz, and 6.19-7.265 GHz. The measured realized gains of the SQTA are 4.4-4.5 dBi, 4.5-4.6 dBi, 4.8-4.9 dBi, and 4.9-4.95 dBi.

  • Microplastics in water resources: Global pollution circle, possible technological solutions, legislations, and future horizon
    • Saeed S. Albaseer
    • Hussein Al-Hazmi
    • Tonni Agustiono Kurniawan
    • Xianbao Xu
    • Sameer A.M. Abdulrahman
    • Peyman Ezzati
    • Sajjad Habibzadeh
    • Henner Hollert
    • Navid Rabiee
    • Eder C. Lima
    • Michael Badawi
    • Mohammad Saeb
    2024 SCIENCE OF THE TOTAL ENVIRONMENT

    Beneath the surface of our ecosystems, microplastics (MPs) silently loom as a significant threat. These minuscule pollutants, invisible to the naked eye, wreak havoc on living organisms and disrupt the delicate balance of our environment. As we delve into a trove of data and reports, a troubling narrative unfolds: MPs pose a grave risk to both health and food chains with their diverse compositions and chemical characteristics. Nevertheless, the peril extends further. MPs infiltrate the environment and intertwine with other pollutants. Worldwide, microplastic levels fluctuate dramatically, ranging from 0.001 to 140 particles.m-3 in water and 0.2 to 8766 particles.g-1 in sediment, painting a stark picture of pervasive pollution. Coastal and marine ecosystems bear the brunt, with each organism laden with thousands of microplastic particles. MPs possess a remarkable ability to absorb a plethora of contaminants, and their environmental behavior is influenced by factors such as molecular weight and pH. Reported adsorption capacities of MPs vary greatly, spanning from 0.001 to 12,700 μg·g−1. These distressing figures serve as a clarion call, demanding immediate action and heightened environmental consciousness. Legislation, innovation, and sustainable practices stand as indispensable defenses against this encroaching menace. Grasping the intricate interplay between microplastics and pollutants is paramount, guiding us toward effective mitigation strategies and preserving our health ecosystems.

  • Microstructural evolution and mechanical behavior of activated tungsten inert gas welded joint between P91 steel and Incoloy 800HT
    • Vishwa Bhanu
    • J. Manoj
    • Ankur Gupta
    • Dariusz Fydrych
    • Chandan Pandey
    2024 INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY

    This study examines the welded joint between P91 steel and Incoloy 800HT using the Activated Tungsten Inert Gas (A-TIG) welding process. The focus is on analyzing the microstructure and evaluating the mechanical properties of joints made with different compositions of activating flux. Owing to the reversal of the Marangoni effect in which the conventional direction of molten metal flow in the weld pool is reversed due to the application of oxide-based fluxes, a complete depth of penetration of 8 mm was successfully achieved. Conducting mechanical tests, such as microhardness, tensile, and Charpy impact toughness tests, elucidates the behavior of the welded specimens under different loading conditions. The findings highlight the effects of grain size, dislocations, and the evolution of fine-sized precipitates in the high-temperature matrix. This study highlights the importance of choosing suitable flux compositions to achieve consistent penetration and dilution in the base metals. Insights into different failure modes and the influence of temperature on the tensile strength were evaluated. Beneficial mechanical properties of the joints (meeting the criteria of ISO and ASTM standards) were found: ultimate tensile strength of 585 ± 5 MPa, elongation 38 ± 2%, impact toughness of 96  5 J, and maximum microhardness of 345 ± 5 HV.

  • Microstructure and mechanical properties of a dissimilar metal welded joint of Inconel 617 and P92 steel with Inconel 82 buttering layer for AUSC boiler application
    • Amit Kumar
    • Sachin Sirohi
    • Manohar Singh
    • Dariusz Fydrych
    • Chandan Pandey
    2024 INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING

    The application of the novel dissimilar metal welded (DMW) joint, utilizing Inconel 617 and P92 steel, was showcased in the advanced ultra-supercritical (AUSC) boiler. The work has been performed to investigate the effect of Inconel 82 (ERNiCr-3) buttering layer on microstructure and mechanical properties (high-temperature tensile strength, impact strength and microhardness) of gas tungsten arc welded (GTAW) dissimilar joint between Inconel 617 and P92 steel fabricated using the Inconel 617 (ERNiCrCoMo-1) filler. For optical microscopy and scanning electron microscopy (SEM), samples were machined along a transverse direction which comprised the butter layer, weld metal, and heat-affected zone of both sides. The energy-dispersive X-ray spectroscopy (EDS) was used to map the interface of the buttering layer and weld metal and butter layer and P92 steel. The high-temperature tensile testing and Charpy impact testing at room temperature were conducted for the integrity assessment of the welded joint. The examination of microstructure and hardness revealed that the buttering layer of Inconel 82 filler successfully mitigated a significant portion of the brittle martensitic microstructure from the coarse-grained heat-affected zone (CGHAZ), along with hardness peaks on the side of P92 steel. The conventional method of DMW joint fabrication, without the use of a buttering layer, has been demonstrated to be less favourable compared to the new fabrication method, which incorporates a buttering layer. The TiC/NbC carbides were identified in the Inconel 82 buttering layer, whereas M23C6 and Mo6C carbides were found in the Inconel 617 filler weld. Near the interface of the Inconel 82 buttering layer and P92 steel, the formation of peninsula and island structures, as well as Type I and Type II boundaries, were confirmed. Additionally, element diffusion of Ni, Cr, and Fe was observed. The tensile test results indicated an ultimate tensile strength of 620 ± 4 MPa and % elongation of 19 ± 4 % at room temperature, with fracture occurring in the buttering layer near the interface of the buttering layer and P92 steel. At temperatures of 550 °C and 650 °C, the ultimate tensile strength decreased to 448 MPa and 326 MPa, respectively, with fractures occurring in the P92 steel, irrespective of temperature. The hardness of the Inconel 82 buttering layer and Inconel 617 filler weld were 219 ± 10 HV and 248 ± 11 HV, respectively.

  • Microwave-Induced Processing of Free-Standing 3D Printouts: An Effortless Route to High-Redox Kinetics in Electroanalysis
    • Kornelia Kozłowska
    • Mateusz Cieślik
    • Adrian Koterwa
    • Krzysztof Formela
    • Jacek Ryl
    • Paweł Niedziałkowski
    2024 Materials

    3D-printable composites have become an attractive option used for the design and manufacture of electrochemical sensors. However, to ensure proper charge-transfer kinetics at the electrode/electrolyte interface, activation is often required, with this step consisting of polymer removal to reveal the conductive nanofiller. In this work, we present a novel effective method for the activation of composites consisting of poly(lactic acid) filled with carbon black (CB-PLA) using microwave radiation. A microwave synthesizer used in chemical laboratories (CEM, Matthews, NC, USA) was used for this purpose, establishing that the appropriate activation time for CB-PLA electrodes is 15 min at 70 °C with a microwave power of 100 W. However, the usefulness of an 80 W kitchen microwave oven is also presented for the first time and discussed as a more sustainable approach to CB-PLA electrode activation. It has been established that 10 min in a kitchen microwave oven is adequate to activate the electrode. The electrochemical properties of the microwave-activated electrodes were determined by electrochemical techniques, and their topography was characterized using scanning electron microscopy (SEM), Raman spectroscopy, and contact-angle measurements. This study confirms that during microwave activation, PLAs decompose to uncover the conductive carbon-black filler. We deliver a proof-of-concept of the utility of kitchen microwave-oven activation of a 3D-printed, free-standing electrochemical cell (FSEC) in paracetamol electroanalysis in aqueous electrolyte solution. We established satisfactory limits of linearity for paracetamol detection using voltammetry, ranging from 1.9 μM to 1 mM, with a detection limit (LOD) of 1.31 μM.

  • Mieszanki betonowe stosowane w technologii druku trójwymiarowego
    • Andrzej Ambroziak
    2024 Przegląd Budowlany

    W niniejszej pracy dokonano przeglądu literatury z zakresu mieszanek i zapraw betonowych stosowanych w druku trójwymiarowym. Przegląd literatury przygotowano z zachowaniem chronologii pojawienia się danej publikacji (daty publikacji). Na podstawie przeprowadzonego przeglądu dokonano tabelarycznego zestawienia receptur mieszanek wykorzystywanych w wydrukach trójwymiarowych (3D). Przedstawiony przegląd literatury z zakresu mieszanek i zapraw betonowych stosowanych w druku trójwymiarowym można traktować jako wstęp do szczegółowych badań związanych z projektowaniem nowych typów mieszanek i receptur.

  • Migration of trace elements and radioisotopes to various fractions of solid wastes generated as a result of the sewage sludge incineration process
    • Oskar Ronda
    • Bartłomiej Cieślik
    • Barbara Piotrowska
    • Krzysztof Isajenko
    • Satoki Okabayashi
    • Koichi Chiba
    • Motohiro Tsuboi
    • Justyna Płotka-Wasylka
    2024 Pełny tekst WASTE MANAGEMENT

    The research was aimed at providing new knowledge in the field of chemical characteristics of solid waste generated in the process of combustion of sewage sludge in fluidized bed furnaces. The research material consisted of disposed fluidized beds (DFB), sewage sludge ash (SSA) and air pollution control residues (APC) from three Polish installations for the thermal treatment of sewage sludge. Natural radionuclides as well as anthropogenic isotope 137Cs were determined in the tested materials and the migration of a wide spectrum of trace elements to various waste fractions generated in the process of sewage sludge combustion was examined. It was observed that both radioisotopes and most of the trace elements determined accumulate in SSA and DFB, while the APC fraction contains a much smaller amount of them. The exceptions are mercury and selenium, whose volatile compounds migrate to the exhaust gas dedusting system and accumulate in the APC fraction (up to 40 mg/kg and 13 mg/kg, respectively). A potential threat from the 226Ra isotope in SSA is identified in the context of the management of this waste in the production of building materials because the typical activity of 226Ra in SSA collected from areas with very low Ra content in natural environment exceeds 1.5–6 times the activity of this isotope in conventional cement mixtures. When managing SSA and DFB, special attention should be paid to the content of metalloids such as As, B and Se, due to the high content of mobile forms of these elements in the mentioned materials.

  • Millimeter Wave Negative Refractive Index Metamaterial Antenna Array
    • Rao Aziz
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2024 Pełny tekst Scientific Reports

    In this paper, a novel negative refractive index metamaterial (NIM) is developed and characterized. The proposed metamaterial exhibits negative effective permittivity (εeffe) and negative effective permeability (µeffe) at millimeter wave frequency of 28GHz. This attractive feature is utilized to enhance the gain of a microstrip patch antenna (MPA). Two thin layers of 5  5 subwavelength unit cell array of NIM are placed above a single MPA to enhance the gain of the antenna. Each unit cell has an area of 3.4  3.4 mm2. A gain increase of 7.9dBi has been observed when using the proposed NIM as a superstrate. Furthermore, the NIM array is placed over a 2  2 array of MPAs with four ports to demonstrate versatility of the metamaterial. The total size of the 2  2 antenna array system with N-MTM is about 61.1  34  16mm3 (5.71λ  3.18λ  1.5λ, where λ is the free-space wavelength at 28 GHz). The measurement result indicate that the maximum gain of the antenna array is 13.5dBi. A gain enhancement of 7.55 dB in E-Plane and 7.25 dB in H-Plane at the resonant frequency of 28 GHz is obtained. The proposed antenna structure is suitable for 5G millimeter wave communications, in particular, for possible implementation in future millimeter wave access points and cellular base stations.

  • Millimeter Wave Retrodirective Van Atta Arrays in LTCC Technology
    • Kamil Trzebiatowski
    • Martin Ihle
    • Benedykt Sikorski
    • Łukasz Kulas
    • Krzysztof Nyka
    2024 Pełny tekst

    The millimeter wave Van Atta arrays, intended for chipless RFID applications and fabricated in LTCC technology, are presented in this paper. The arrays are designed for 24 GHz and 60 GHz bands. The method for an easy modification of the RCS characteristic by increasing the number of single-dimensional arrays, intended for increasing the RCS level, is also presented. The LTCC manufacturing process is described in detail. The fabricated arrays are characterized in an anechoic chamber and exhibit RCS levels up to -26 dBsm with a small 51 x 17 mm footprint.

  • Millimeter Wave Wideband and Low-Loss Compact Power Divider Based on Gap Waveguide: For Use in Wideband Antenna Array System
    • Arefeh Kalantari Khandani
    • Ali Farahbakhsh
    • Davood Zarifi
    • Ashraf Uz Zaman
    2024 Pełny tekst IEEE Access

    This paper presents a wideband and low-loss design of a compact power divider based on gap waveguide technology. The proposed power divider consists of two adjacent E-plane groove gap waveguide and a small ridge section to couple and equally divide the EM energy from the input E-plane groove gap waveguide to the two output ones in-phase. The simulation results show that the proposed waveguide power divider has about 40% impedance bandwidth while its size is 0.7λ×0.6λ at the center frequency. An 8-way power divider is designed using the proposed 2-way power divider and the back-to-back configuration of the 8-way one is fabricated to investigate the performance of the proposed design. In addition, to show the application of the presented power divider, a wideband linear horn antenna array is designed and fabricated. The measured results agree well with the simulated ones and prove the excellent low-loss and wide bandwidth of the proposed power divider over the band of interest from 50-75GHz. The measured S11 of the entire 8-way power divider remains below -10 dB level, the insertion loss is around 1 dB over the band of interest. Also, the S11 of the horn array integrated with the 8-way feed network remains below -10 dB and the low sidelobes of the radiation pattern of the entire horn array indicates excellent phase and amplitude balance for the power divider over the entire bandwidth of interest.

  • Miniaturization-Oriented Design of Spline-Parameterized UWB Antenna for In-Door Positioning Applications
    • Adrian Bekasiewicz
    • Tom Dhaene
    • Ivo Couckuyt
    • Jacek Litka
    2024

    Design of ultra-wideband antennas for in-door localization applications is a challenging task. It involves development of geometry that maintains appropriate balance between the size and performance. In this work, a topologically-flexible monopole has been generated using a stratified framework which embeds a gradient-based trust-region (TR) optimization algorithm in a meta-loop that gradually increases the structure dimensionality. The optimization has been performed using a composite objective function that maintains acceptable size/performance trade-off. The final design features a reflection below –10 dB within the UWB spectrum and a small footprint of only 182 mm2. The considered method has been benchmarked against a standard TR-based routine executed directly on a multi-dimensional electromagnetic model of the antenna.

  • Miniaturized and Lightweight ESPAR Antenna for WSN and IoT Applications
    • Luiza Leszkowska
    • Mateusz Czeleń
    • Mateusz Rzymowski
    • Krzysztof Nyka
    • Łukasz Kulas
    2024 Pełny tekst

    A new compact ESPAR antenna is investigated in this paper. The proposed antenna has 12 directional radiation patterns based on 12 passive elements and can be successfully used in Wireless Sensor Network applications. In proposed antenna design, the possibilities of 3D printing were used to implement a dielectric miniaturization overlay that allowed for reducing antenna occupied area by almost 60% and antenna profile by 27% in comparison to the standard ESPAR antenna. The total dimensions of the antenna are 98 mm in diameter and 20.25 mm in height, while the weight of the antenna is only 86 g, which makes it much more suitable for potential use in UAV-based wireless communication applications.

  • Miniaturized Dual-Band Bandpass Filter with Wide Inter Stopband for 5G Applications
    • Earla Shankar
    • Kanaparthi V. Phani Kumar
    • Vamsi Krishna Velidi
    • Sławomir Kozieł
    2024 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS

    This article presents the design of a miniaturized dual-band bandpass filter with a wide inter-stopband and improved isolation. A novel topology comprising the series connection of shunt cascaded coupled lines and quarter-wavelength open stubs is proposed to realize the dual-band filter along with half-wavelength stepped-impedance stubs. The circuit characteristics contain nine transmission zeros and four poles. The transmission zeros frequencies of the dual-band filter response have been theoretically verified using even-odd mode analysis. For experimental validation purposes, a dual-band filter with a center frequency ratio of 5.17 covering 5G applications (N12 & N48) has been implemented and fabricated using the microstrip technology. The full-wave simulated and measured filter responses are in good congruence.

  • Minikin’s equation mistake — a mystic art of systems of measuring units
    • Waldemar Magda
    2024 PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-MARITIME ENGINEERING

    This paper deals with one of the most controversial equations in coastal engineering — the so-called Minikin’s equation, describing the impact pressure due to wave breaking on a vertical-wall caisson of a composite breakwater. This equation has been used worldwide for many years, although it has been reported many times to overestimate real values of the impact pressure measured in nature and in the laboratory. Units of measurement, problems with dimensionality of parameters and conversion between different unit systems were suspected as causes. This paper explores in rigorous detail the reason behind the problems associated with Minikin’s equation. After a thorough literature review and a detailed analysis of all previously published forms of Minikin’s equation, a question of coherence/incoherence of systems of measuring units has been specially addressed. By adopting the incoherent English Engineering system of units, the most proper and satisfactory explanation of the curious mistake in Minikin’s formula has been found and formally correct forms of the equation, followed by appropriate units of measurement, are presented.

  • Minimization of a ship's magnetic signature under external field conditions using a multi-dipole model
    • Mirosław Wołoszyn
    • Jarosław Tarnawski
    2024 Pełny tekst Scientific Reports

    The paper addresses the innovative issue of minimizing the ship's magnetic signature under any external field conditions, i.e., for arbitrary values of ambient field modulus and magnetic inclination. Varying values of the external field, depending on the current geographical location, affect only the induced part of ship's magnetization. A practical problem in minimizing the ship signature is separating permanent magnetization from induced magnetization. When the ship position changes, a signature measurement has to be made under new magnetic field conditions to update the currents in the coils. This is impractical or even difficult to do (due to the need for a measuring ground), so there is a need to predict the ship's magnetization value in arbitrary geographical location conditions based on the reference signature determined on the measuring ground. In particular, the model predicting the signatures at a new geographical location must be able to separate the two types of magnetization, as permanent magnetization is independent of external conditions. In this paper, a FEM model of the vessel is first embedded in an external field and permanent magnetization is simulated using DC coils placed inside the model. Then, using the previously developed rules for data acquisition and determination of model parameters, a multi-dipole model is synthesized in which the induced and permanent parts are separated. The multi-dipole model thus developed has been successfully confronted with the initial model in FEM environment. The separation of permanent and induced magnetization allows the latter to be scaled according to new values of the external field. In the paper, the situation of determining a signature at one geographical position and its projection onto two other positions is analyzed. Having determined the signature with a high degree of accuracy anywhere in the world, it is possible to perform classical signature minimization by determining DC currents in coils placed inside the ship's hull. The paper also analyzes the effectiveness of ship's signature minimization and the influence of ship's course on the signature value. The advantage of the method presented in this paper is an integrated approach to the issue of scaling and minimization of ship magnetic signature, which has not been presented in the literature on such a scale before.

  • Min-max optimization of node‐targeted attacks in service networks
    • Bernard Fortz
    • Mariusz Mycek
    • Michał Pióro
    • Artur Tomaszewski
    2024 NETWORKS

    This article considers resilience of service networks that are composed of service and control nodes to node-targeted attacks. Two complementary problems of selecting attacked nodes and placing control nodes reflect the interaction between the network operator and the network attacker. This interaction can be analyzed within the framework of game theory. Considering the limited performance of the previously introduced iterative solution algorithms based on non-compact problem models, new compact integer programming formulations of the node attack optimization problem are proposed, which are based on the notion of pseudo-components and on a bilevel model. The efficiency of the new formulations is illustrated by the numerical study that uses two reference networks (medium-size and large-size), and a wide range of the sizes of attacks and controllers placements.

  • M-integral for finite anti-plane shear of a nonlinear elastic matrix with rigid inclusions
    • Victor Eremeev
    • Konstantin Naumenko
    2024 Pełny tekst INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE

    The path-independent M-integral plays an important role in analysis of solids with inhomogeneities. However, the available applications are almost limited to linear-elastic or physically non-linear power law type materials under the assumption of infinitesimal strains. In this paper we formulate the M-integral for a class of hyperelastic solids undergoing finite anti-plane shear deformation. As an application we consider the problem of rigid inclusions embedded in a Mooney–Rivlin matrix material. With the derived M-integral we compute weighted averages of the shear stress acting on the inclusion surface. Furthermore, we prove that a system of rigid inclusions can be replaced by one effective inclusion.

  • Missing Puzzle Pieces in Dementia Research: HCN Channels and Theta Oscillations
    • Paulina Kaźmierska-Grębowska
    • Maciej Jankowski
    • Bruce M. MacIver
    2024 Pełny tekst Aging and Disease

    Increasing evidence indicates a role of hyperpolarization activated cation (HCN) channels in controlling the resting membrane potential, pacemaker activity, memory formation, sleep, and arousal. Their disfunction may be associated with the development of epilepsy and age-related memory decline. Neuronal hyperexcitability involved in epileptogenesis and EEG desynchronization occur in the course of dementia in human Alzheimer’s Disease (AD) and animal models, nevertheless the underlying ionic and cellular mechanisms of these effects are not well understood. Some suggest that theta rhythms involved in memory formation could be used as a marker of memory disturbances in the course of neurogenerative diseases, including AD. This review focusses on the interplay between hyperpolarization HCN channels, theta oscillations, memory formation and their role(s) in dementias, including AD. While individually, each of these factors have been linked to each other with strong supportive evidence, we hope here to expand this linkage to a more inclusive picture. Thus, HCN channels could provide a molecular target for developing new therapeutic agents for preventing and/or treating dementia.

  • Mixed-use buildings as the basic unit that shapes the housing environment of smart cities of the future
    • Mateusz Gerigk
    2024 Środowisko Mieszkaniowe

    The contemporary approach to creating the residential function is confronted with the trend of increasing the volume of buildings and expectations regarding the future urban environment focused on sustainable development. This paper presents an overview of the residential structure in the context of defined thematic scopes. Namely, it is a systemic approach to the problem of designing mixed-use buildings which create a modern residential structure in developing urban centres. The creation of smart cities from existing urban areas and newly designed centres involves comprehensively defined design guidelines. The key is the integrity and interoperability of the dynamic structure which can serve as a basis for developing new systems and/or improving the existing ones. The developed model structure for creating and maintaining the system is based on a genetic algorithm and is presented in the form of a neural network that involves the use of artificial intelligence (AI). The specific structure is intended as a tool to support supervision and decision-making in the process of designing and managing contemporary mixed-use buildings in their newly planned surroundings.

  • MnWO4/reduced graphene oxide-based electrochemical sensing platform for simultaneous detection of catechol and resorcinol
    • Somayeh Tajik
    • Reza Zaimbashi
    • Fariba Garakani Nejad
    • Mohammad Taghi Tourchi Moghadam
    • Mohammad Bagher Askari
    • Hadi Beitollahi
    2024 DIAMOND AND RELATED MATERIALS

    n this study, a novel electrochemical sensor for accurate and sensitive catechol determination was demonstrated employing a screen-printed graphite electrode (SPGE) modified with MnWO4/reduced graphene oxide (MnWO4/rGO) nanocomposite. The MnWO4/rGO nanocomposite has been successfully prepared by using hydrothermal technique, and it was then characterized using several microscopic and spectroscopic methods (XRD, FE-SEM, and EDS). SPGE modified with MnWO4/rGO nanocomposite compared to the unmodified SPGE by creating a synergistic effect and having unique properties (large surface area of MnWO4 nanoparticles along with high electrical conductivity and large surface area of rGO sheets) by enhancing the speed of electron transfer and effective interaction of the analyte with the electrode surface, significantly improved the efficiency of electrochemical reactions and the catalytic effect for detection of catechol. The MnWO4/rGO/SPGE response was shown to be linear with the change in catechol concentration in the concentration range of 0.01–600.0 μM under optimal conditions, and the detection limit was 0.005 μM, utilizing the differential pulse voltammetry (DPV) technique. Moreover, as a means of simultaneous detection of catechol and resorcinol, the modified SPGE demonstrated good catalytic performance. These two analytes' oxidation peaks were completely separated, with an apparent peak potential difference of 380 mV, which made it possible to determine both of these chemicals simultaneously. Eventually, catechol and resorcinol were effectively detected in water samples with acceptable recovery values.

  • Mobilenet-V2 Enhanced Parkinson's Disease Prediction with Hybrid Data Integration
    • Sameer Ahmad Bhat
    • Piotr Szczuko
    2024 Pełny tekst

    This study investigates the role of deep learning models, particularly MobileNet-v2, in Parkinson's Disease (PD) detection through handwriting spiral analysis. Handwriting difficulties often signal early signs of PD, necessitating early detection tools due to potential impacts on patients' work capacities. The study utilizes a three-fold approach, including data augmentation, algorithm development for simulated PD image datasets, and the creation of a hybrid dataset. MobileNet-v2 is trained on these datasets, revealing higher generalization or prediction accuracy of 84% with hybrid datasets. Future research will explore the impact of high variability synthetic datasets on prediction accuracies and investigate the MobileNet-v2 architecture's memory footprint for timely inferences with low latency

  • Modal modification of structural damping applied to increase the stability and convergence of numerical integration
    • Krzysztof Lipiński
    2024 Pełny tekst

    The presented paper refers to numerical tests done on systems fused of multibody and finite-element parts. The appearance of its multibody part gives rise to significant nonlinear components, i.e., second-order nonlinear differential equations express the dynamics. We usually solve these equations by “step-by-step” integration methods. When using the currently available integration algorithms, we approximate these initial systems of equations by their associated sets of difference equations. The resulting approximated answers enclose superfluous solutions not related to the true one. Calculation that does not magnify these approximation errors is called numerically stable. The initial task is to find robust algorithms, i.e., such that do not produce extraordinarily different results for tiny changes in the initial data. We should underline that numerical instability is a phenomenon due to the employed numerical method but not due to the problem itself. We apply a modal modification of the damping matrix to eliminate these instabilities. The idea of modal modification is not a novelty. We should recall the modal reduction of system degrees of freedom as the example (suppression of its highest damped modes). With the Author's proposition, we do not eliminate these modes but reduce their damping to correlate them with the user-optimal time step. The highest damped modes of the resulting model diminish slower but still under the supposition of vanishing in a period lower than the assumed interval of the observations.

  • Model Management for Low-Computational-Budget Simulation-Based Optimization of Antenna Structures Using Nature-Inspired Algorithms
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    2024 APPLIED SOFT COMPUTING

    The primary objective of this study is investigation of the possibilities of accelerating nature-inspired optimization of antenna structures using multi-fidelity EM simulation models. The primary methodology developed to achieve acceleration is a model management scheme which the level of EM simulation fidelity using two criteria: the convergence status of the optimization algorithm, and relative quality of the individual designs within the solution pool. The search process is initiated using the lowest-fidelity (therefore, the fastest) EM model. The fidelity is step-by-step increased towards the conclusion of the process. At the same time, lower-quality designs are evaluated at lower resolution level as compared to the better ones. Our technique has been extensively validated using several microstrip antennas, and particle swarm optimization (PSO) algorithm as the search engine. The obtained results demonstrate that making the EM model fidelity dependent on just the convergence status of the algorithm allows for relative savings from forty to seventy percent, depending on the algorithm setup. At the same time, managing model fidelity as a function of both convergence status and relative design quality (within the population processed by the algorithm) allows for up to 85 percent savings, as compared to high-fidelity-based algorithms. Furthermore, the achieved acceleration is not detrimental to the optimization process reliability. Apart from the computational efficiency, the attractive feature of the proposed approach is implementation simplicity and versatility: the presented management scheme can be readily incorporated into most nature-inspired routines.

  • Model oceny dojrzałości przedsiębiorstw do zastosowania zwinnych metodyk zarządzania projektami IT
    • Piotr Zejer
    2024 Pełny tekst

    Dysertacja koncentruje się na budowie modelu, który ocenia gotowość przedsiębiorstw do wdrożenia zwinnych metodyk zarządzania projektami IT. Analizuje istniejące metody oceny dojrzałości projektowej i wprowadza własny model, biorąc pod uwagę krytyczne czynniki sukcesu i skuteczność zwinnych metod. Rozprawa zawiera badania literaturowe, empiryczne studium przypadku oraz weryfikację i rekomendacje modelu, dostarczając wglądu w praktyczne zastosowanie zwinnych metod zarządzania projektami w sektorze IT. Głównym celem modelu jest wskazanie uwarunkowań i obszarów funkcjonalnych przedsiębiorstwa, które wymagają poprawy dla skutecznego stosowania tych metod. Praca dostarcza praktycznego narzędzia dla organizacji, umożliwiającego ocenę ich dojrzałości w kontekście zwinnych praktyk zarządzania projektami, co ma kluczowe znaczenie dla sukcesu projektów IT w dynamicznie zmieniającym się środowisku biznesowym.

  • Model Pomorskiej Nagrody Jakości w świetle wyników badań opinii stron zainteresowanych
    • Anna Wendt
    • Piotr Grudowski
    2024 Problemy Jakości

    Cel - prezentacja oryginalnego modelu wykorzystywanego do oceny/samooceny organizacji w regionalnym konkursie o Pomorską Nagrodę Jakości na podstawie oceny dotychczasowych doświadczeń oraz badania opinii i potrzeb głównych interesariuszy tej inicjatywy. Podstawowym założeniem przy opracowaniu tego modelu jest jego dostosowanie do współczesnych trendów dotyczących doskonałości organizacyjnej oraz upowszechnienie jego stosowania jako obiektywnej podstawy ewaluacji skuteczności i efektywności organizacji prywatnych i publicznych. Projekt badania, metodyka badawcza, koncepcja - na podstawie integracyjnego przeglądu literatury określono cel opracowania. Dla osiągnięcia tego celu przeprowadzono badania empiryczne, które wykorzystują studium przypadku (case study) konkursów o Pomorską Nagrodę Jakości. W tym kontekście zastosowano metody badań jakościowych takie jak ustrukturyzowane wywiady bezpośrednie, analizę materiałów źródłowych oraz obserwacje uczestniczące. Wyniki/ wnioski - uczestnicy konkursów pozytywnie ocenili proces organizacji konkursu. Dostrzegali jednak problemy związane z wykorzystaniem arkusza samooceny. Były to m.in. zbyt duża pracochłonność związana z wypełnianiem arkusza przez uczestników konkursu oraz niezrozumienie zawartych w nim stwierdzeń i pojęć. Uwagi te potwierdzili także organizatorzy konkursu. W związku z aktualizacją Modelu EFQM, na którego założeniach i zasadach opierały się stosowane dotąd kryteria konkursowe, postanowiono uaktualnić Model Pomorskiej Nagrody Jakości. W tym celu wykorzystano Model EFQM w wersji z roku 2020, aktualną wersję modelu CAF oraz wnioski z przeprowadzonych przez autorów badań jakościowych. Opracowano nową wersję kwestionariusza samooceny oraz dostosowano skalę ocen i punktację stanowiącą podstawę określenia wyników w konkursach. Zastosowanie praktyczne - opracowany w roku 2023 model oceny w ramach Pomorskiej Nagrody Jakości może być stosowany jako podstawa rozwoju systemu zarządzania organizacją. Ankieta samooceny jest narzędziem doskonalenia obejmującym wiele obszarów działalności organizacji. Sam udział w konkursie jest poświadczeniem wysokiego poziomu świadomości projakościowej organizacji oraz sprzyjać może wymianie dobrych praktyk na szczeblu regionalnym oraz krajowym i międzynarodowym.

  • Modele biznesu akademickich spółek spin-off w Polsce
    • Kamil Brodnicki
    2024

    Przesłankami do podjęcia tematu w niniejszej pracy były luki badawcze dotyczące m.in. braku jednoznacznego i spójnego pojmowania akademickich spółek spin-off. Podmiotem badań były akademickie spółki spin-off w Polsce, utworzone w latach 2011 – 2020, za pośrednictwem spółek celowych uczelni, natomiast przedmiotem badań były modele biznesu tychże spółek. Celem głównym dysertacji było: zweryfikowanie i zdefiniowanie modeli biznesu akademickich spółek spin-off w Polsce, powstałych przy udziale spółek celowych uczelni, wraz z elementami stanowiącymi te modele. W części teoretycznej zawarto zagadnienia opisujące spółki spin-off, dokonano przeglądu literatury przedmiotu, koncentrując się na akademickim podejściu do ich tworzenia i funkcjonowania. Ponadto przedstawiono rozważania definicyjne, zagadnienia klasyfikacyjne oraz podstawy prawne tworzenia akademickich spółek spin-off w Polsce. Opisano czynniki sprzyjające tworzeniu i funkcjonowaniu oraz bariery ograniczające powstawanie tychże spółek. Przedstawiono również rozważania dotyczące definicji pojęcia modelu biznesu na podstawie przeglądu krajowej i zagranicznej literatury przedmiotu oraz elementy kształtujące ten model. W części empirycznej przedstawiono metodykę badań (badania ilościowe i jakościowe), zastosowane narzędzia i metody badawcze (m.in. kwestionariusz ankietowy, Analiza Głównych Składowych - PCA, Analiza Wiązkowa - Cluster Analysis, Analiza Korelacji, Analiza porównawcza) oraz wyniki z przeprowadzonych badań. W dysertacji opracowano autorski teoretyczny model biznesu akademickich spółek spin-off oraz bazę spółek celowych i akademickich spółek spin-off w Polsce. Zdefiniowano i sklasyfikowano czynniki oddziałujące na modele biznesu akademickich spółek spin-off w świetle prowadzonych badań empirycznych, tj. determinanty, ocena cech inicjatora/założyciela, które oddziaływały na zakładanie akademickiej spółki spin-off, bariery wewnętrzne i zewnętrzne mające wpływ na proces zakładania i funkcjonowania akademickich spółek spin-off. Następnie dokonano weryfikacji modeli biznesu akademickich spółek spin-off funkcjonujących w Polsce. W wyniku przeprowadzonych analiz PCA i CA oraz analizy porównawczej stwierdzono pięć rodzajów modeli akademickich spółek spin-off, z czego tylko jeden model jest tożsamy z modelem opisanym w literaturze, zaś pozostałe cztery modele biznesu nie zostały dotychczas scharakteryzowane w teorii.

  • Modeling and Accuracy Assessment of Determining the Coastline Course Using Geodetic, Photogrammetric and Satellite Measurement Methods: Case Study in Gdynia Beach in Poland
    • Francesco Giuseppe Figliomeni
    • Mariusz Specht
    • Claudio Parente
    • Cezary Specht
    • Andrzej Stateczny
    2024 Pełny tekst Electronics

    The coastal environment represents a resource from both a natural and economic point of view, but it is subject to continuous transformations due to climate change, human activities, and natural risks. Remote sensing techniques have enormous potential in monitoring coastal areas. However, one of the main tasks is accurately identifying the boundary between waterbodies such as oceans, seas, lakes or rivers, and the land surface. The aim of this research is to evaluate the accuracy of coastline extraction using different datasets. The images used come from UAV-RGB and the Landsat-9 and Sentinel-2 satellites. The method applied for extracting the coast feature involves a first phase of application of the Normalized DifferenceWater Index (NDWI), only for satellite data, and consequent application of the maximum likelihood classification, with automatic vectorization. To carry out a direct comparison with the extracted data, a coastline obtained through a field survey using a Global Navigation Satellite System (GNSS) device was used. The results are very satisfactory as they meet the minimum requirements specified by the International Hydrographic Organization (IHO) S-44. Both the UAV and the Sentinel-2 reach the maximum order, called the Exclusive order (Total Horizontal Uncertainty (THU) of 5 m with a confidence level of 95%), while the Landsat-9 falls into the Special order (THU of 10 m with a confidence level of 95%).

  • Modeling and Strength Calculations of Parts Made Using 3D Printing Technology and Mounted in a Custom-Made Lower Limb Exoskeleton
    • Szczepan Śpiewak
    • Wiktoria Wojnicz
    • Jan Awrejcewicz
    • Magdalena Mazur
    • Michał Ludwicki
    • Bartosz Stańczyk
    • Bartłomiej Zagrodny
    2024 Pełny tekst Materials

    This study is focused on the application of 3D-printed elements and conventional elements to create a prototype of a custom-made exoskeleton for lower limb rehabilitation. The 3D-printed elements were produced by using Fused Deposition Modeling technology and acrylonitrile butadiene styrene (ABS) material. The scope of this work involved the design and construction of an exoskeleton, experimental testing of the ABS material and numerical research by using the finite element method. On the basis of the obtained results, it was possible to deduce whether the load-bearing 3D-printed elements can be used in the proposed mechanical construction. The work contains full data of the material models used in FEM modeling, taking into account the orthotropic properties of the ABS material. Various types of finite elements were used in the presented FE models. The work is a comprehensive combination of material testing issues with the possibility of implementing the obtained results in numerical strength models of machine parts.

  • Modeling lignin extraction with ionic liquids using machine learning approach
    • Karol Baran
    • Beata Barczak
    • Adam Kloskowski
    2024 Pełny tekst SCIENCE OF THE TOTAL ENVIRONMENT

    Lignin, next to cellulose, is the second most common natural biopolymer on Earth, containing a third of the organic carbon in the biosphere. For many years, lignin was perceived as waste when obtaining cellulose and hemicellulose and used as a biofuel for the production of bioenergy. However, recently, lignin has been considered a renewable raw material for the production of chemicals and materials to replace petrochemical resources. In this context, an increasing demand for high-quality lignin is to be expected. It is, therefore, essential to optimize the technological processes of obtaining it from natural sources, such as biomass. In this work, an investigation of the use of machine learning-based quantitative structure-property relationship (QSPR) modeling for the preliminary processing of lignin recovery from herbaceous biomass using ionic liquids (ILs) is described. Training of the models using experimental data collected from original publications on the topic is assumed, and molecular descriptors of the ionic liquids are used to represent structural information. The study explores the impact of both ILs' chemical structure and process parameters on the efficiency of lignin recovery from different bio sources. The findings give an insight into the extraction process and could serve as a foundation for further design of efficient and selective processes for lignin recovery using ionic liquids, which can have significant implications for producing biofuels, chemicals, and materials.

  • Modeling of free vibrations and resonant frequencies of simply-supported submerged horizontal plate
    • Justyna Slawinska-Budzich
    • Wojciech Sulisz
    • Jarosław Przewłócki
    2024 Pełny tekst PLOS ONE

    A theoretical approach was applied to study the vibration of simple-supported submerged horizontal plate. The derived analytical solution was used to determine natural frequencies for a horizontal plate vibrating in fluid. The investigations were conducted for a very wide range of material density and elasticity modulus covering all materials used in engineering practice. Analysis shows that plate vibration frequency decreases with increasing plate width and draft, and decreases with decreasing plate thickness. Moreover, the results show that a substantial effect on vibration of submerged plate has mass of water above plate. The results also show that plate vibration frequency decreases with increasing plate material density and decreases with decreasing elasticity modulus. The dominant factors affecting the vibration of the submerged plate are the plate width, the plate thickness, and elasticity modulus. For moderate and low values of elasticity modulus, vibration frequency is becoming lower than frequency of water waves. This is very important because wave frequencies overlap with the natural plate vibration frequencies, which may lead to resonance and failure of a structure. The problem is that the overlap of plate vibration frequencies and wave frequencies occurs for very wide range of wave and plate parameters. Laboratory experiments confirm theoretical results.