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Gdańsk University of Technology

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Publications from the year 2024

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  • Robust asymptotic super twisting sliding mode observer for non-linear uncertain biochemical systems
    • Mateusz Czyżniewski
    • Rafał Łangowski
    2024 JOURNAL OF PROCESS CONTROL

    The problem of state estimation (reconstruction of the state vector) for a given class of biochemical systems under uncertain system dynamics has been addressed in this paper. In detail, the bioreactor at a water resource recovery facility represents the considered biochemical systems. The biochemical processes taking place in the bioreactor have been modelled using an activated sludge model. Based on this model, an appropriate utility model has been derived for estimation purposes. The internal dynamics of the model have been burdened with unstructured and parametric uncertainty due to the unknown reaction kinetics functions. Taking this uncertainty into account, an analysis of the observability and detectability of the utility model has been carried out. The utility model and the available set of inputs and measured outputs have been used to design a new robust non-linear observer that allows the estimation of state variables in the presence of uncertainty. In the synthesis of the observer, the asymptotic observer methodology has been combined with a second-order sliding mode observer, a so-called super twisting algorithm. The developed observer generates not only robust and stable estimates of the state variables but also enables the reconstruction of unknown kinetic functions. The stability of the designed observer has been proven using the Lyapunov stability theory. The observer has been implemented in the Matlab/Simulink environment. The comprehensive simulation studies carried out show the high efficiency of the estimation process using the developed state observer.

  • Rola zieleni w kształtowaniu tożsamości przestrzennej miasta na przykładzie Gdyni
    • Maura Zaworska
    2024

    Istnienie miast bez zieleni jest prawie niemożliwe, dlatego rola zieleni w kształtowaniu tożsamości przestrzennej miast była ważnym czynnikiem przy podejmowaniu prób tworzenia zieleni tam urządzonej. Sztuka kształtowania terenów zieleni w Gdyni obecna była od początku istnienia miasta, a nawet wcześniej. W pracy uporządkowano aparat pojęciowy związany z zagadnieniami architektury krajobrazu towarzyszącymi pojęciom tożsamości przestrzennej. Zebrano i usystematyzowano podstawowe definicje w oparciu o przegląd literatury naukowej i doświadczenia własne autorki. W kolejnych etapach pracy omówiono ewolucję koncepcji zieleni miejskiej oraz tendencje jej projektowania. Wykazano, że wraz ze wzrostem świadomości przemian cywilizacyjnych złożoność zagadnień przyrodniczych staje się domeną interdyscyplinarnych dyskursów nad rolą zieleni w kształtowaniu przyszłości życia w terenach zurbanizowanych. Od końca XIX wieku wyraźny jest wzrost świadomego udziału zieleni w kształtowaniu tożsamości przestrzennej miast. Wskazano, że zieleń komponowana w Gdyni towarzyszyła jej rozwojowi już w okresie przedmiejskim i była nieodłącznym elementem rozwoju miasta w okresie dwudziestolecia międzywojennego, następnie wojny i okresu powojennego aż do dziś. Na podstawie przeglądu literatury wskazano, że pamięć o przeszłości Gdyni stanowi istotny element w kształtowaniu jej tożsamości przestrzennej oraz że występuje silny związek terenów zieleni z kreowaniem tożsamości przestrzennej miasta. W różnych okresach rozwojowy miasta relacja ta przyjmuje odmienny charakter, bazując na innych komponentach przyrodniczych oraz ideowych....

  • Role of buttering layer composition on microstructural heterogeneity and mechanical properties of Alloy 617 and P92 steel dissimilar welded joints for future Indian AUSC program
    • Saurabh Rathore
    • Amit Kumar
    • Sachin Sirohi
    • Vivek Singh
    • Ankur Gupta
    • Dariusz Fydrych
    • Chandan Pandey
    2024 INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY

    Restrictive operating conditions (even exceeding 700 °C) of materials in advanced ultra super critical (AUSC) power plants and the need to minimize manufacturing and maintenance costs require the production of dissimilar metal welded joints (DMW). Significant differences in the physical and chemical properties of welded materials lead to phenomena that reduce the weldability of the metals used and force the search for solutions that limit unfavorable phenomena, e.g., the use of buttering layers. The study presents a comparison of two types of joints with Alloy 617 (UNS N06617) and ferritic P92 (UNS K92460) steel made using Inconel 82 (ENiCrFe-3) and Inconel 617 (ERNiCrCoMo-1) alloys buttering layer and the corresponding chemical composition of filler metals. All areas of the joints made with the gas tungsten arc welding process were subjected to structural investigations (optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) and mechanical tests (microhardness, room and high temperature tensile, and toughness testing). Despite the more complicated welding procedure, sound welded joints were obtained with favorable properties resulting, inter alia, from the reduced thickness of the martensite layer in HAZ of P92 steel and the limited diffusion of alloy components compared to welded joints without the buttering layer. This also resulted in a reduction of the maximum hardness (especially in the case of Inconel 82 buttering—by 15–30 HV0.5 in comparison with Inconel 617 buttering) and an increase in strength while limiting the decrease in plasticity (even 663 MPa tensile strength and 21% of elongation for Inconel 617 buttered joint). Moreover, improved high-temperature performance (approximately 70–100 MPa) of the welded joint following the application of the buttering layer was confirmed. The presented results allow for drawing general conclusions that both proposed welding procedures can be recommended for use in the working conditions occurring at AUSC.

  • Room vs. Body Temperature to Evaluate Electrical Interface Parameters of State-Of-The-Art PEDOT : PSS-Based Electrodes
    • Karolina Cysewska
    2024 ChemElectroChem

    In this work, the effect of the simulated body fluid temperature on the electrical interface parameters of the state-of-the-art PEDOT-PSS electrode was studied. PEDOT-PSS was synthesized by electrodeposition on graphite and gold-coated-graphite electrodes. All electrochemical measurements were performed in phosphate-buffered saline aqueous solution (pH 7.4) at room temperature (25 °C) and body temperature (37 °C). The results of the work confirmed that the modification of the carbon or metallic electrode with conducting polymer PEDOT : PSS significantly reduced the interfacial impedance and improved charge storage capacity and current injection limit due to its high electroactive surface area, roughness and porosity compared to the bare substrates. The work showed that solution temperature is a critical factor that can influence the electrical interface parameters of electrodes for neural stimulation. Understanding and controlling these temperature-dependent effects are essential for ensuring the reliability, safety, and efficacy of neural stimulation applications in both research and clinical settings.

  • Rotating rod and ball
    • Sergey Kryzhevich
    • Alexander Plakhov
    2024 JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS

    We consider a mechanical system consisting of an infinite rod (a straight line) and a ball (a massless point) on the plane. The rod rotates uniformly around one of its points. The ball is reflected elastically when colliding with the rod and moves freely between consecutive hits. A sliding motion along the rod is also allowed. We prove the existence and uniqueness of the motion with a given position and velocity at a certain time instant. We prove that only 5 kinds of motion are possible: a billiard motion; a sliding motion; a billiard motion followed by sliding; a sliding motion followed by a billiard one; and a constant motion when the ball is at the center of rotation. The asymptotic behaviors of time intervals between consecutive hits and of distances between the points of hits on the rod are determined.

  • Rotational stiffness of a connection made using a single prestressed bolt
    • Paweł Pieczka
    • Piotr Iwicki
    2024 Full text ENGINEERING STRUCTURES

    The often overlooked rotational stiffness of connections utilizing a single prestressed bolt leads to the common assumption of treating such connections as pinned or even modeling them as rigid. Nevertheless, considering the friction between interconnected elements, it is evident that the actual rotational stiffness lies between these simplified assumptions. This study is dedicated to quantifying this stiffness and addressing the question of whether simplifying such connections to pinned or rigid is justifiable. Experimental, theoretical, and numerical analyses were conducted. The results reveal a substantial variability in this phenomenon, which can be effectively described by a normal distribution. Illustrated through a case study involving built-up battened columns, it was demonstrated that the maximum normal force in the column, when considering rotational stiffness of connections, significantly surpasses that obtained for a model assuming pinned connections. This underscores the necessity of employing a model with nonlinear rotational stiffness for an accurate analysis of such constructions.

  • Rotor flux and EEMF observer for interior permanent magnet synchronous machine
    • Deepak Vyas
    • Marcin Morawiec
    • Daniel Wachowiak
    2024 Full text Bulletin of the Polish Academy of Sciences-Technical Sciences

    In recent years, the use of the interior permanent magnet synchronous machine (IPMSM) in various applications has grown significantly due to numerous benefits. Sensors are used to achieve high efficiency and good dynamic response in IPMSM drives but due to their high cost and reduced overall size of the system, sensorless control techniques are preferred. Non-sinusoidal distribution of rotor flux and slot harmonics are present in the considered IPMSM. In this article, these problems are considered control system disturbances. With the above-mentioned problems, the classical observer structure based on (d-q) fails to estimate at low-speed ranges. This article proposes an observer structure based on a rotor flux vector in (-) stationary reference frame, which works using the adaptive control law to estimate speed and position, and a non-adaptive EEMF-based observer to estimate speed and position. Moreover, a comparative analysis between both observer structures at different speed ranges is also considered in this article. The effectiveness of the observer structure is validated by simulation tests and experimental tests using the sensorless control system with a field-oriented control scheme for a 3.5 kW IPMSM drive system.

  • Rozwój nowej generacji bezzałogowych pojazdów nawodnych i podwodnych z wykorzystaniem zaawansowanych technologii i osiągnięć w zakresie zastosowania systemów sterowania przez sztuczną inteligencję AI
    • Mirosław Gerigk
    • Mateusz Gerigk
    2024

    Ostatnia dekada to ciągła praca nad dalszym rozwojem i wdrażaniem bezzałogowych pojazdów morskich. Między nimi są autonomiczne pojazdy podwodne (ang. autonomous underwater vehicle - AUV) i bezzałogowe pojazdy nawodne (ang. unmanned surface vehicle - USV). Niektóre pojazdy USV mogą być typu WIG (ang. wing in ground, 'w ziemi'), co związane jest z wykorzystaniem efektu przypowierzchniowego występującego w czasie ruchu skrzydła w pobliżu powierzchni czy swobodnej powierzchni wody. Rośnie zainteresowanie opracowywaniem i wdrażaniem w pełni rozwiniętych implementacji bezzałogowych pojazdów morskich. Głównym motorem rozwoju takich pojazdów są technologie, takie jak innowacyjne formy kadłuba pojazdu, innowacyjne materiały konstrukcyjne, w tym nanomateriały i materiały ,,inteligentne", innowacyjne źródła zasilania w energię, układy napędowe łączące wydajne i ciche silniki i pędniki, technologie systemów autonomicznych, technologie systemów sensorycznych i efektorowych oraz innowacyjne technologie informatyczne, w tym zaawansowane systemy nawigacji, komunikacji i sterowania. Pomiędzy tymi technologiami ważną rolę do odegrania ma sztuczna inteligencja wykorzystywana przez zaawansowane systemy sterowania. Dodatkowy zestaw cech, jakie mogą posiadać morskie pojazdy bezzałogowe, oferują rozwiązania oparte na technologii stealth i biotechnologii.

  • Saint-Venant torsion based on strain gradient theory
    • Przemysław Podulka
    • Wojciech Macek
    2024 INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES

    In this study, the Saint-Venant torsion problem based on strain gradient theory is developed. A total form of Mindlin's strain gradient theory is used to acquire a general Saint-Venant torsion problem of micro-bars formulation. A new Finite Element formulation based on strain gradient elasticity theory is presented to solve the Saint-Venant torsion problem of micro-bars. Moreover, the problem is solved for both micro and macro scale. In addition, six different cross sections in solid and hollow condition are considered, which the Saint-Venant torsion problem is solved on them. Torsional response of micro-bars is predicted by using the modified couple stress theory and the strain gradient theory of Aifantis which both of them employ only one length scale parameter. Some micro-bars with different cross-sectional area are investigated to show the performance of current study and conclusions are drawn from the micron-scale torsional feedback for micro-bars.

  • Sampling-based novel heterogeneous multi-layer stacking ensemble method for telecom customer churn prediction
    • Fatima E. Usman-Hamza
    • Abdullateef O. Balogun
    • Ramoni Tirimisiyu Amosa
    • Luiz Fernando Capretz
    • Hammed Mojeed
    • Shakirat A. Salihu
    • Abimbola G. Akintola
    • Modinat Abolore Mabayoje
    2024 Full text Scientific African

    In recent times, customer churn has become one of the most significant issues in business-oriented sectors with telecommunication being no exception. Maintaining current customers is particularly valuable due to the high degree of rivalry among telecommunication companies and the costs of acquiring new ones. The early prediction of churned customers may help telecommunication companies to identify the causes of churn and design industrial tactics to address or mitigate the churn problem. Controlling customer churn by developing efficient and reliable customer churn prediction (CCP) solutions is essential to achieving this objective. Findings from existing CCP studies have shown that numerous methods, such as rule-based and machine-learning (ML) mechanisms, have been devised to solve the CCP problem. Nonetheless, the problems of adaptability and the resilience of rule-based CCP solutions are its major weaknesses, and the skewed pattern of churn datasets (class imbalance) is detrimental to the prediction performances of conventional ML models in CCP. Hence, this research developed a robust heterogeneous multi-layer stacking ensemble method (HMSE) for effective CCP. Specifically, in the HMSE method, the prediction prowess of five ML classifiers (Random Forest (RF), Bayesian network (BN), Support Vector Machine (SVM), K-Nearest Neighbour (KNN), and Repeated Incremental Pruning to Produce Error Reduction (RIPPER)) with distinct computational characteristics are ensembled based on stacking and the resulting model is further enhanced using a forest penalizing attribute (FPA) model. The synthetic minority oversampling technique (SMOTE) is integrated with the proposed HMSE to balance the skewed class label present in the original experimental datasets. Extensive tests were carried out to determine the effectiveness of the proposed HMSE and S-HMSE on standard telecom CCP datasets. Observed findings from the experimental results showed that HMSE and S-HMSE can effectively predict churners even with the class imbalance (skewed datasets) problem. In addition, comparison studies demonstrated that the suggested S-HMSE offered improved prediction performance and optimum solutions for CCP in the telecom sector in comparison with baseline classifiers, homogeneous ensemble methods, and current CCP approaches.

  • Scale transformations in model exchange potentials in low energy electron-atom scattering
    • Felipe Arretche
    • Eliton Popovicz Seidel
    • Wagner Tenfen
    2024 JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA

    Model exchange potentials are particularly interesting to account for the indistinguishability between the projectile and target electrons in electron-atom scattering in vacuo and plasma environments. It is well known that their performance is pretty satisfactory in the high energies but also that discrepancies from the results obtained with exact exchange are found toward the zero energy limit. In this article, we examine how well established model exchange potentials based on the free electron gas approach compare to phase shifts calculated considering exchange in exact form. In particular, we show that the Hara and the semiclassical exchange potentials are able to reproduce reference low energy phase shifts through a simple scale transformation, in opposition to the previous approaches where energy dependent corrections to the local momentum were adopted. We provide the scale factors and phase shifts for electron scattering by He, Ne and Ar atoms for < 1,0 a.u. Such scaling factors can be determined reproducing the scattering length and the number of s-wave bound states from exact exchange calculations. We also show that the scaling procedure works for electronic densities that present the physically correct asymptotic behavior. The present results are important to the research field, since they form the basis to construction of scattering models based on optical potential approaches.

  • Schemat powstawania rys na przykładzie osiowo rozciąganego pręta żelbetowego
    • Marek Wesołowski
    • Maciej Solarczyk
    2024 Full text Inżynieria i Budownictwo

    W artykule przedstawiono w sposób schematyczny ideę powstawania kolejnych rys w konstrukcjach żelbetowych na przykładzie osiowo rozciąganego pręta. Opisano początkowy oraz końcowy stan zarysowania. Wyprowadzono wzór na szerokość rysy. Przedstawiono interpretację geometryczną rys dla fazy początkowego zarysowania oraz efekt tension stiffening na przykładzie elementu osiowo rozciąganego. Przedstawiono przykładowe obliczenia miary efektu tension stiffening, szerokości rys oraz średnich naprężeń przyczepności dla fazy początkowych rys.

  • Schottky Junction-Driven Photocatalytic Effect in Boron-Doped Diamond-Graphene Core–Shell Nanoarchitectures: An sp3/sp2 Framework for Environmental Remediation
    • Surya Kanta Ghadei
    • Mateusz Ficek
    • Salila Kumar Sethy
    • Jacek Ryl
    • Mukul Gupta
    • Ramasamy Sakthivel
    • Kamatchi J Sankaran
    • Robert Bogdanowicz
    2024 ACS Applied Materials & Interfaces

    Self-formation of boron-doped diamond (BDD)-multilayer graphene (MLG) core–shell nanowalls (BDGNWs) via microwave plasma-enhanced chemical vapor deposition is systematically investigated. Here, the incorporation of nitrogen brings out the origin of MLG shells encapsulating the diamond core, resulting in unique sp3/sp2 hybridized frameworks. The evolution mechanism of the nanowall-like morphology with the BDD-MLG core–shell composition is elucidated through a variety of spectroscopic studies. The photocatalytic performance of these core–shell nanowalls is examined by the deterioration of methylene blue (MB) and rhodamine B (RhB) dyes beneath low-power ultraviolet (UV) light irradiation. Starting with 5 ppm dye solutions and employing BDGNWs as the photocatalyst, remarkable degradation efficiencies of 95% for MB within 100 min and 91% for RhB within 220 min are achieved. The effect of varying dye concentrations was also examined. The enhanced photocatalytic activity is driven by carrier photogeneration and mediated by the Schottky junction formed between BDD and MLG, promoting efficient photoinduced charge separation. The stability of the BDGNW photocatalyst is examined, and after five test runs, the photocatalytic behavior for MB and RhB degradation decreases to 87 and 85%, respectively, from initial values of 96 and 91%, demonstrating excellent photostability. These findings underscore the significance of diamond-graphene nanoarchitectures as promising green carbonaceous photocatalysts.

  • Screening evaluation of the quality of commercially available cigars, cigarillos, and bidis based on emission levels of selected terpenes and terpenoids
    • Mariusz Marć
    • Sylwia Bednarska
    • Paweł Hać
    • Piotr Konieczka
    2024 MICROCHEMICAL JOURNAL

    The aim of the research was to verify the use of the solvent-free, non-destructive and easy to operate analytical method to study and compare the emissions of 16 representatives of terpenes and terpenoids from commercially available cigars, cigarillos and bidis − a potential screening analysis for the quality of combustible tobacco products. To assess the amount of organic compounds emitted to the gaseous phase from investigated tobacco samples, the stationary emission chambers system (at the sample conditioning stage) and gas chromatography with flame ionization detector (at the final analyte determination stage) were used. Studied samples represented five origins: the Dominican Republic, Nicaragua, Mexico, Cuba, and India and two manufacture approaches: machine-made and handmade. The assessed values of total volatile organic compounds (TVOCs) was from 0.58 to 28 µg·g−1 (at 60 °C) and from 26 to 430 µg·g−1 (at 120 °C). For Dominican products, Camphene and α-Cedrene were characterized by the highest emission level (233 ± 34 ng·g−1 and (3.7 ± 1.4) × 102 ng·g−1, respectively). In a case of Mexican and Cuban products it was noticed that the emission level of determined terpenes and terpenoids is higher in the case of hand-rolled tobacco products than mechanically manufactured ones. In a case of Nicaraguan hand-rolled products, Camphene, L-(−)-Fenchone, and α-Cedrene were characterized by the highest emission rate at 120 °C (213 ± 81 ng·g−1, 191 ± 45 ng·g−1 and 213 ± 84 ng·g−1, respectively). The highest emission level for Indian products in 120 °C was observed for α-Cedrene and Geranyl Acetate – respectively 181.6 ± 4.4 ng·g−1 and 101 ± 13 ng·g−1. The results of this study may indicate that sometimes cheaper products such as cigarillo have an emission profile that classifies them between expensive products such as “large cigars.”

  • Screening of perfluoroalkyl substances and their environmental impact in sequencing batch reactors combined with nature-based solutions
    • Grażyna Gałęzowska
    • Katarzyna Kołecka
    • Monika Cieszyńska-Semenowicz
    • Vladyslaw Redko
    • Magdalena Gajewska
    2024 Full text ECOLOGICAL ENGINEERING

    Perfluoroalkyl substances (PFAS) are a growing problem in the environment. The research indicates that they are present in surface water, groundwater, drinking water sources, wastewater treatment plant (WWTP) effluents, and landfill leachates. Additionally, the conventional methods of wastewater treatment are ineffective in their removal. This study aimed to indicate the concentration of PFAS in wastewater during treatment processes in sequential biological reactors (SBRs), followed by two ponds working in series. Samples were collected after individual stages of treatment, during the beginning of touristic seasonality. The research also determined the environmental impact of the PFAS by determining the ecotoxicity and performing a risk assessment of the analyzed wastewater. The analyzed wastewater samples were collected from the different stages of the WWTP in Swarzewo, which uses SBRs. In the collected samples, basic parameters such as total suspended solids (TSS), biological oxygen demand (BOD5), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), as well as identification and concentrations of PFAS were determined. Based on this data, an ecotoxicological assessment and risk assessment of the wastewater was performed. The research indicated that the basic parameters and Microtox toxicity assay are not sensitive to changes in the PFAS content in wastewater. As the hydrophobicity of the PFAS increases, their solubility in the water decreases. However, these substances may still be present in suspended particles, leading to an increase in their global concentration in the water and, consequently, may pose environmental hazards. The proposed technology of wastewater treatment is an effective PFAS retention system in the sediment (removal of over 90 %). Meteorological conditions affect the PFAS transformation processes taking place in SBRs.

  • Screening stability, thermochemistry, and chemical kinetics of 3-hydroxybutanoic acid as a bifunctional biodiesel additive
    • Mohamed A. Abdel-Rahman
    • Abolfazl Shiroudi
    • Jacek Czub
    • Hao Zhao
    2024 Full text JOURNAL OF PHYSICAL CHEMISTRY A

    The thermo-kinetic aspects of 3-hydroxybutyric acid (3-HBA) pyrolysis in the gas phase were investigated using density functional theory (DFT), specifically the M06-2X theoretical level in conjunction with the cc-pVTZ basis set. The obtained data were compared with benchmark CBS-QB3 results. The degradation mechanism was divided into 16 pathways, comprising 6 complex fissions and 10 barrierless reactions. Energy profiles were calculated and supplemented with computations of rate coefficients and branching ratios over the temperature range of 600–1700 K at a pressure of 1 bar using transition state theory (TST) and Rice–Ramsperger–Kassel–Marcus (RRKM) methods. Thermodynamics results indicated the presence of six stable conformers within a 4 kcal mol–1 energy range. The estimated chemical kinetics results suggested that TST and RRKM approaches are comparable, providing confidence in our calculations. The branching ratio analysis reveals that the dehydration reaction pathway leading to the formation of H2O and CH3CH═CHCO2H dominates entirely at T ≤ 650 K. At these temperatures, there is a minor contribution from the simple homolytic bond fission reaction, yielding related radicals [CH3•CHOH + •CH2CO2H]. However, at T ≥ 700 K, this reaction becomes the primary decomposition route. At T = 1700 K, there is a minor involvement of a reaction pathway resulting in the formation of CH3CH(OH)•CH2 + •CHO(OH) with an approximate contribution of 16%, and a reaction leading to [•CH3 + •CH2OHCH2CO2H] with around 9%.

  • Segmentation-Based BI-RADS ensemble classification of breast tumours in ultrasound images
    • Maciej Bobowicz
    • Mikołaj Badocha
    • Katarzyna Gwozdziewicz
    • Marlena Rygusik
    • Paulina Kalinowska
    • Edyta Szurowska
    • Tomasz Dziubich
    2024 Full text INTERNATIONAL JOURNAL OF MEDICAL INFORMATICS

    Background: The development of computer-aided diagnosis systems in breast cancer imaging is exponential. Since 2016, 81 papers have described the automated segmentation of breast lesions in ultrasound images using arti- ficial intelligence. However, only two papers have dealt with complex BI-RADS classifications. Purpose: This study addresses the automatic classification of breast lesions into binary classes (benign vs. ma- lignant) and multiple BI-RADS classes based on a single ultrasonographic image. Achieving this task should reduce the subjectivity of an individual operator’s assessment. Materials and Methods: Automatic image segmentation methods (PraNet, CaraNet and FCBFormer) adapted to the specific segmentation task were investigated using the U-Net model as a reference. A new classification method was developed using an ensemble of selected segmentation approaches. All experiments were performed on publicly available BUS B, OASBUD, BUSI and private datasets. Results: FCBFormer achieved the best outcomes for the segmentation task with intersection over union metric values of 0.81, 0.80 and 0.73 and Dice values of 0.89, 0.87 and 0.82, respectively, for the BUS B, BUSI and OASBUD datasets. Through a series of experiments, we determined that adding an extra 30-pixel margin to the segmentation mask counteracts the potential errors introduced by the segmentation algorithm. An assembly of the full image classifier, bounding box classifier and masked image classifier was the most accurate for binary classification and had the best accuracy (ACC; 0.908), F1 (0.846) and area under the receiver operating char- acteristics curve (AUROC; 0.871) in the BUS B and ACC (0.982), F1 (0.984) and AUROC (0.998) in the UCC BUS datasets, outperforming each classifier used separately. It was also the most effective for BI-RADS classification, with ACC of 0.953, F1 of 0.920 and AUROC of 0.986 in UCC BUS. Hard voting was the most effective method for dichotomous classification. For the multi-class BI-RADS classification, the soft voting approach was employed. Conclusions: The proposed new classification approach with an ensemble of segmentation and classification approaches proved more accurate than most published results for binary and multi-class BI-RADS classifications.

  • Seismic probabilistic assessment of steel and reinforced concrete structures including earthquake-induced pounding
    • Farzin Kazemi
    • Neda Asgarkhani
    • Ahmed Manguri
    • Robert Jankowski
    2024 Full text Archives of Civil and Mechanical Engineering

    Recent earthquakes demonstrate that prioritizing the retrofitting of buildings should be of the utmost importance for enhancing the seismic resilience and structural integrity of urban structures. To have a realistic results of the pounding effects in modeling process of retrofitting buildings, the present research provides seismic Probability Factors (PFs), which can be used for estimating collision effects without engaging in intricate and time-intensive analysis. To include the low-, to mid-rise buildings, the 3-Story, 5-Story, and 9-Story adjacent steel and Reinforced Concrete (RC) moment-resisting frames were modeled in OpenSees software capable to take into account the structure in a state of collapse during the analysis, which can provide the real condition of buildings under seismic excitations. Results of analysis confirmed that the impact force can considerably affect the moment–rotation curve of beams and columns, in which, it can affect the structural response of structures during earthquakes. Therefore, seismic PFs proposed to examine the possibility of changes in the performance levels and fragility assessments. Moreover, proposed PFs can be used as coefficient factors to facilitate the retrofitting process of buildings and improve the environmental effects.

  • Seismic response and performance prediction of steel buckling-restrained braced frames using machine-learning methods
    • Neda Asgarkhani
    • Farzin Kazemi
    • Anna Jakubczyk-Gałczyńska
    • Benyamin Mohebi
    • Robert Jankowski
    2024 Full text ENGINEERING APPLICATIONS OF ARTIFICIAL INTELLIGENCE

    Nowadays, Buckling-Restrained Brace Frames (BRBFs) have been used as lateral force-resisting systems for low-, to mid-rise buildings. Residual Interstory Drift (RID) of BRBFs plays a key role in deciding to retrofit buildings after seismic excitation; however, existing formulas have limitations and cannot effectively help civil engineers, e.g., FEMA P-58, which is a conservative estimation method. Therefore, there is a need to provide a comprehensive tool for estimating seismic responses of Interstory Drift (ID) and RID with novel approaches to fulfill the shortcomings of existing formulas. The Machine Learning (ML) method is an interdisciplinary approach that makes it possible to solve these types of engineering problems. Therefore, the current study proposes ML algorithms to provide a prediction model for determining the seismic response, seismic performance curve, and seismic failure probability curve of BRBFs. To train ML-based prediction models, Nonlinear Time-History Analysis (NTHA) and Incremental Dynamic Analysis (IDA) were performed on the 2-, to 12-Story BRBFs subjected to 78 far-field ground motions, and 606944 data points were prepared for different prediction purposes. The results indicate that the considered approaches are justified. For instance, the proposed ML methods have the ability to predict the maximum ID, maximum RID and maximum roof ID with the accuracy of even 98.7%, 95.2%, and 93.8%, respectively, for the 4-Story BRBF. Moreover, a general preliminary estimation tool is introduced to provide predictions based on the input parameters considered in the study.

  • Selected aspects of performance of organic Rankine cycles incorporated into bioenergy with carbon capture and storage using gasification of sewage sludge
    • Kamil Stasiak
    • Paweł Ziółkowski
    • Dariusz Mikielewicz
    2024 Full text JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME

    The study aims to investigate the application of the Organic Rankine Cycle (ORC) in the bioenergy with carbon capture and storage (BECCS) using gasification of sewage sludge. The tool used in the investigation is the Aspen Plus software with REFPROP property methods for calculating fluid properties. The reason for this study is that a detailed analysis of the proposed BECCS process flow diagram indicates that a certain amount of waste heat is available in the exhaust gas from the high-to-intermediate pressure gas turbine. Some of this energy can be used by applying expansion in a low-pressure turbine, optionally by applying of regenerative water heating, which is then redirected to the combustion chamber, or finally by incorporating the ORC into the main cycle. For the ORC cycle, different configurations are studied, with regeneration and using different working fluids. For the highest efficiency of the cycle, the regenerative heating of high-pressure water is applied and a suitable ORC working fluid with optimal saturation parameters and mass flow is selected. Such modified proposed BECCS power plant hybrid systems with ORC are compared to the reference case with lower pressure expansion. A study of the heat duty and temperature distribution in heat exchangers is carried out. Five ORC fluids were investigated, namely ethanol, refrigerants R236-ea, R245-fa, R1233zd(E) and water, which gave a net efficiency of the whole power plant of 39.71%, 40.02%, 40.26%, 40.34% and 39.35% respectively, while the proposed BECCS reference case gave 38.89%.