Publikační činnost VŠB-TUO ve Web of Science / Publications of VŠB-TUO in Web of Science

Permanent URI for this collectionhttp://hdl.handle.net/10084/56138

Kolekce obsahuje bibliografické záznamy článků akademických pracovníků VŠB-TUO v časopisech indexovaných ve Web of Science od roku 1990 po současnost. Odkaz na Web of Science je funkční ze sítě VŠB-TUO, vzdálený přístup viz web ÚK VŠB-TUO.

Do kolekce jsou zařazeny:

a) publikace, u nichž je v originálních dokumentech jako působiště autora (adresa) uvedena Vysoká škola báňská – Technická univerzita Ostrava (VŠB-TUO),

b) publikace, u nichž v originálních dokumentech není v adrese VŠB-TUO uvedena, ale autoři prokazatelně v době jejich zpracování a uveřejnění působili na VŠB-TUO.

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Now showing 1 - 20 out of 7813 results

Electric vehicle charging by use of renewable energy technologies: A comprehensive and updated review
(Elsevier, 2024) Nazari, Mohammad Alhuyi; Blažek, Vojtěch; Prokop, Lukáš; Mišák, Stanislav; Prabaharan, Natarajan
The majority of the vehicles in the world consuming fossil fuels that causes emissions of harmful greenhouse gases. In order to mitigate the emissions regarding the transport sector, Electric Vehicles (EVs) have attracted attentions. One of the main concerns in the development of EVs is supply of required power for the charging stations. Renewable energy systems would be clean and attractive options for supply of required power of charging stations. In recent years, several studies have investigated applications of renewable energy systems for charging stations of EV and analyzed different aspects of these technologies. This article reviews the research works on the design, optimization and performance investigation of charging stations coupled with renewable energy systems. Studies on EV charging systems powered by stand-alone or hybrid renewable energy systems are considered in the present article. According to the reviewed works, significant potential of renewable energy systems for supply of charging stations can be concluded. Different factors such as the applied technology and components, meteorological data of the installation site and operating condition influence the performance of these systems. Furthermore, it can be concluded that control design system can influence various aspects of EV charging technologies powered by renewable energy systems such as share of renewables in the grid -connected configurations and performance reliability. Challenges and opportunities associated with the development of these systems are provided in the current works and some recommendations are highlighted for the forthcoming studies and projects.
Load monitoring and appliance recognition using an inexpensive, low-frequency, data-to-image, neural network, and network mobility approach for domestic IoT systems
(IEEE, 2024) Fazio, Peppino; Mehić, Miralem; Vozňák, Miroslav
With the low integration costs and quick development cycle of all-IP-based 5G+ technologies, it is not surprising that the proliferation of IP devices for residential or industrial purposes is ubiquitous. Energy scheduling/management and automated device recognition are popular research areas in the engineering community, and much time and work have been invested in producing the systems required for smart city networks. However, most proposed approaches involve expensive and invasive equipment that produces huge volumes of data (high-frequency complexity) for analysis by supervised learning algorithms. In contrast to other studies in the literature, we propose an approach based on encoding consumption data into vehicular mobility and imaging systems to apply a simple convolutional neural network to recognize certain scenarios (devices powered on) in real time and based on the nonintrusive load monitoring paradigm. Our idea is based on a very cheap device and can be adapted at a very low cost for any real scenario. We have also created our own data set, taken from a real domestic environment, contrary to most existing works based on synthetic data. The results of the study's simulation demonstrate the effectiveness of this innovative and low-cost approach and its scalability in function of the number of considered appliances.
Reformer + Membrane separator plant for decarbonized hydrogen production from Biogas/Biomethane: An experimental study combined to energy efficiency and exergy analyses
(Elsevier, 2024) Ruales, Henry Bryan Trujillo; Spadafora, Alex; Fiore, Piergiuseppe; Vereš, Ján; Caravella, Alessio; Iulianelli, Adolfo
Nowadays, the world energy production is still based on the exploitation of fossil fuels, mainly oil, coal, and natural gas, responsible for large greenhouse emissions in the environment. According to the measures proposed by the European Green Deal to meet the carbon neutrality by 2050, the decarbonisation of the global energy production processes represents a top priority. Hydrogen represents a carbon-free energy carrier, useful to drive the society toward a decarbonized-economy. The novelty of this work is represented by the experimental generation of clean hydrogen by a two stages plant constituted of a biogas/biomethane steam reformer and a Pd-Ag membrane separator, meanwhile applying on this simple case the methodology of the exergy analysis, identifying the main losses and suggesting improvements. Hence, it deals with the exergy analysis of the whole system with the process intensification operated by the membrane separator adopted instead of using several stages to separate/purify hydrogen - as conventionally done after the reforming stage (two water gas shift reactors, high and low temperature, followed by a pressure swing adsorption stage) - with the objective of recovering decarbonized hydrogen coming from the biogas/biomethane steam reformer, meeting the European targets indicated by the Clean Hydrogen Alliance. This approach allowed to understand the amount of irreversibilities present in such a system as well as how the thermal efficiency may be influenced by a number of parameters, constituting globally a baseline for the scaling up of this process technology from lab to bench/pilot scale. The best results of this work highlight that the utilization of biomethane in the feed stream to generate hydrogen resulted to be a better choice than biogas in terms of thermal efficiency (based on the lower heating value) of the whole system, equal to 73 % at 773 K, while the highest percentage of exergy destruction was concentrated in the condensation stage, with values varying between 76 % and 93 %, depending on the feed stream typology. The two stages system was able to meet the "decarbonized hydrogen production target 2027", with a hydrogen recovery of 90 % and a purity of 99.9999 %. Last but not least, the overall exergy destroyed efficiency of the overall system in the two analyzed cases was 92 % (biomethane feed stream) and 88 % (biogas feed stream), respectively.
Pit lake slope stability under water level variations
(MDPI, 2024) Steiakakis, Emmanouil; Syllignakis, Georgios; Galetakis, Michail; Vavadakis, Dionysios; Renaud, Vincent; Al Heib, Marwan; Burda, Jan
This paper presents the results of a geotechnical investigation regarding the slope stability in a pit lake, emphasizing the impact of water level variations. Advanced analysis techniques were utilized for this study. The research was performed by using fully coupled flow-deformation analyses. For the fully coupled approach, Bishop's effective-stress equation was used, and for the description of soil hydraulic behavior, the Van Genuchten's model was applied. The analysis of slope stability associated with reservoir water level changes revealed that the slope tended to become unstable as the water level decreased; the stability factor was negatively related to the rate of water level reduction. Concerning the water level fluctuations, the analyses revealed that the soil mass seemed to become less stable as the rate of water level change increased. Under a specific range of rates of water level variation, the safety factor became higher as the number of fluctuations increased. Additionally, the simulation results concerning the water level rising indicate that the pressure due to the external water level acts on the slope surface with a positive impact on the stability factor. The results obtained reflect the effects under a specific site condition, but they can be used as a reference for evaluating slope stability in a pit lake design.
Influence of the chemical composition of leachates on the results of ecotoxicity tests for different slag types
(Elsevier, 2024) Pavlovský, Jiří; Seidlerová, Jana; Pěgřimočová, Zuzana; Vontorová, Jiřina; Motyka, Oldřich; Michalska, Monika; Smutná, Kateřina; Roupcová, Petra; Novák, Vlastimil; Matějka, Vlastimil; Vlček, Jozef
In this study, four ecotoxicological tests on Vibrio fischeri bacteria, Sinapis alba L. (white mustard), Daphnia magna S. (daphnia's) and earthworms were performed for three types of aqueous slag (ladle, blast furnace and converter) leachates with two-grain sizes (<4 mm, <10 mm). Concentrations of toxic elements and concentrations of Cr(VI), Ca, Na, Al, and other ions were determined. The raw slags were analyzed using X-ray fluorescence spectroscopy (XRFS), and major substances were determined by X-ray powder diffraction (XRD). The aqueous slag leachates passed ecotoxicological tests and met the required criteria, showing no toxicity to Vibrio fischeri and complying with white mustard test criteria. According to the results of the ecotoxicity tests with daphnia, the blast furnace slag samples were not ecotoxic, while two other slag samples were found to be entirely compliant. Characterization of the slags showed that the effect of element/ion leachability and slag grain size is essential. Biplot principal component analysis (PCA) showed that grain size does not significantly affect the separation of individuals on the plane. A positive correlation on toxicity was found with pH, conductivity, calcium content, dissolved content, salinity and fluoride concentration, whereas a negative correlation was found with magnesium concentration, dissolved organic carbon and potassium concentration. The effective concentration at 50% inhibition (EC50) value for Vibrio fischeri correlated with the first dimension of bivariate assessment. In summary, it was found that the investigated slags can be effectively reused as they comply with regulations and do not endanger the environment.
Application of electrodialysis enhanced with complex formation integrated with electrolysis for treatment of electroplating wastewaters as a new approach to the selective copper recovery
(Elsevier, 2024) Babilas, Dorota; Chromíková, Jitka; Kopyto, Dorota; Leszczyńska-Sejda, Katarzyna; Dydo, Piotr
The electroplating industry produces a large amount of wastewaters containing economically important metals, such as copper. Usually, the copper electroplating wastewaters are diluted and contaminated with ferric ions. Therefore, selective copper resource recovery from wastewater should be a crucial strategy to mitigate environmental change. This paper focuses on gaining new insights into the electrochemical treatment of copper postgalvanic wastewater contaminated with ferric ions and, as a consequence, selective copper preconcentration and finally copper recovery in metallic form. To achieved this goal the integrated method of electrodialysis (ED) enhanced with disodium ethylenediaminetetraacetate (Na2EDTA) as a complexing agent and the electrolysis (EL) was applied. What is limited by using simple ED or EL methods. It was found that, in ED enhanced with complex formation, the Na2EDTA allowed for the selective bonding of ferric ions. The influence of ferric salt concentration and ED parameters on ED performance was evaluated in terms of selectivity rate factor, ferric ion retention, copper(II) recovery and concentration degree. Furthermore, copper recovery from concentrate after ED by EL was examined. It was concluded that the ED enhanced with a Na2EDTA as the complexing agent promoted 92.2% copper(II) recovery with a 2.95-fold increase of copper(II) in the concentrate and with a ferric retention coefficient of 94.3%. Moreover, the EL of concentrate after ED allowed for the effective recovery of copper on the surface of the cathode. Almost 94.49% of copper was recovered with purity of 99.4%. Therefore, the application of ED enhanced with complexation and EL methods can improved selective copper recovery from wastewater contaminated with ferric ions.
An investigation into sheet-Inconel 718 forming with flexible and metal tools - Simulation and experiment
(MDPI, 2024) Balcerzak, Maciej; Rusz, Stanislav; Čada, Radek; Pastrňák, Martin; Hilšer, Ondřej; Greger, Miroslav
The article presents the results of numerical simulations and experimental tests of plastic forming sheets made from the difficult-to-deform nickel alloy Inconel 718 with a thickness of 1 mm, using punches made from elastomeric materials with hardness 50-90 Shore A and steel dies. Elastomeric stamps were created in the form of five layers with a diameter of 160 mm. The influence of the hardness of the elastomeric punches on the geometry of the elements obtained was determined. The dies were made from 90MnCrV8 steel with a hardness of over 60 HRC. Their task was to obtain the expected shape of the element while generating various stress states in specific areas of the semi-finished product. The research was carried out using an original device whose operating principle was based on the Guerin method. The shape and dimensions of the elements made from Inconel 718 nickel alloy were determined by optical 3D scanning. The geometry of the drawpiece showed a significant impact of the hardness of the layered elastomer matrices on the degree of shape reproduction. The results obtained from numerical modeling were confirmed by the results of experimental tests. It has been shown that the hardness of the elastomeric material used for punches for plastic forming Inconel 718 nickel alloy sheets should be adapted to the shape of the drawpiece. It was also found that one of the important aspects of plastic forming sheets using the Guerin method is the tendency to obtain a diversified shape of the final elements.
Solving linear and nonlinear problems using Taylor series method
(De Gruyter, 2024) Veigend, Petr; Nečasová, Gabriela; Šátek, Václav
The article deals with the solution of technical initial value problems. To solve such problems, an analytical or numerical approach is possible. The analytical approach can provide an accurate result; however, it is not available for all problems and it is not entirely suitable for calculation on a computer, due to the limited numerical accuracy. For this reason, the numerical approach is preferred. This approach uses ordinary differential equations to approximate the continuous behaviour of the real-world system. There are many known numerical methods for solving such equations, most of them limited in their accuracy, have a limited region of stability and can be quite slow to achieve the acceptable solution. The numerical method proposed in this article is based on the Taylor series and overcomes the biggest challenge, i.e. calculating higher derivatives. The aim of the article is therefore twofold: to introduce the method and show its properties, and to show its behaviour when solving problems composed of linear and nonlinear ordinary differential equations. Linear problems are modelled by partial differential equations and solved in parallel using the PETSc library. The parallel solution is demonstrated using the wave equation, which is transformed into the system of ordinary differential equations using the method of lines. The solution of nonlinear problems is introduced together with several optimisations that significantly increase the calculation speed. The improvements are demonstrated using several numerical examples that are solved using MATLAB software.
Sustainability assessment of machining Al 6061-T6 using Taguchi-grey relation integrated approach
(Elsevier, 2024) Zaidi, Sajid Raza; Butt, Shahid Ikramullah; Khan, Muhammad Ali; Faraz, Muhammad Iftikhar; Jaffery, Syed Husain Imran; Petrů, Jana
Modern machining requires reduction in energy usage, surface roughness, and burr width to produce finished or near-finished parts. To ensure high surface quality in machining processes, it is crucial to minimize surface finish and minimize burr width, which are considered as significant parameters as specific cutting energy. The objective of this study was to identify the optimal machining parameters for milling in order to minimize surface roughness, burr width, and specific cutting energy. To achieve this, the research investigated the impact of feed per tooth, cutting speed, depth of cut, and number of inserts on the responses across three intervals using Taguchi L9 array. Observing the responses by varying these parameters, underlined the need for multi objective optimisation. Machining conditions of 0.14 mm/tooth fz, 350 m/min Vc and 2 mm ap using 1 cutting insert (exp no 9) was identified as the best machining run using grey relational analysis owing to its highest grey relational grade of 0.936. ANOVA examination identified cutting speed as the leading factor impacting the grey relational grade with 31.07 % contribution ratio, with the number of inserts, depth of cut, and feed per tooth also making notable contributions. Conclusively, machining parameters identified through response surface optimisation resulted in 21.69 % improvement in surface finish, 11.39 % reduction in specific energy consumption, and 6.2 % decrease in burr width on the down milling side albeit with an increase of 9 % in burr width on the up-milling side.
Assessment of different levels of blackcurrant juice and furcellaran on the quality of fermented whey-based beverages using rheological and mechanical vibration damping techniques
(MDPI, 2024) Rejdlová, Anita; Vašina, Martin; Lorencová, Eva; Hružík, Lumír; Salek, Richardos Nikolaos
In the current study, fermented whey-based beverage models with different levels of blackcurrant juice (0; 10; 20; 100% (w/w)) and furcellaran (0.25% and 0.50% (w/w)) were produced and evaluated. Physicochemical, rheological, mechanical vibration damping, and sensory analyses were performed. During fermentation (48 h), the values of pH, density, and total soluble solids decreased. On the other hand, the ethanol content during fermentation increased up to a final content in the range of 0.92-4.86% (v/v). The addition of furcellaran was effective in terms of sediment content decrease to a level of 0.25% (w/w). In general, the samples exhibited non-Newtonian pseudoplastic behaviour. The sensory analysis revealed that the sample with a composition of 20% (w/w) blackcurrant juice and 0.50% (w/w) furcellaran received the highest score.
Analysis of the variations in brain activity in response to various computer games
(World Scientific Publishing Co Pte Ltd, 2024) Vivekanandhan, Gayathri; Karthikeyan, Anitha; Pakniyat, Najmeh; Penhaker, Marek; Krejcar, Ondřej; Namazi, Hamidreza
The influence of video games on the human brain has been a topic of extensive research and discussion. Video games, characterized by their dynamic and immersive qualities, have demonstrated the capacity to impact diverse cognitive processes. In this study, we conducted a detailed analysis of brain response variations to different genres of computer games, specifically focusing on boring, calm, horror, and funny games. To achieve this, we computed the sample entropy and approximate entropy of electroencephalograms (EEG) signals recorded from participants while they engaged with each type of game. Our findings revealed that EEG signals exhibited the highest complexity during the funny game and the lowest complexity during the calm game. This suggests that the brain is most active when playing the funny game and least active during the calm game. These results provide valuable insights into how different types of video game content can influence brain activity. The methodology employed in this study can be extended to explore brain activity under various conditions, potentially offering a broader understanding of how different stimuli impact cognitive processes. This approach can be useful in examining the effects of various interactive media on brain function and could inform the design of video games and other digital experiences to optimize cognitive engagement and mental well-being.
Exploring kinetics and mass transfer in photocatalytic CO2 reduction: Impact of photocatalyst loading and stirrer speed
(Elsevier, 2024) Ballari, María de los Milagros; Filip Edelmannová, Miroslava; Ricka, Rudolf; Reli, Martin; Kočí, Kamila
CO2 photocatalytic reduction is a potential and promising technology to reduce the level of the greenhouse gas in the atmosphere but also as an alternative and renewable fuel resource. However, the products yield of the reaction is still low and the identification of the optimal operating conditions that affect the process are still needed to be determined. This study investigates the impact of key operational parameters, specifically photocatalyst concentration and stirring speed, on the photocatalytic reduction of CO2 in a slurry batch photoreactor utilizing synthesized TiO2. A simplified photocatalytic kinetic model, incorporating the radiation field within the photoreactor, was developed, considering mass transfer from liquid to gas phase for the primary detected reaction products (CO, CH4, and H2). The proposed models elucidate the influence of different operating conditions on product yields. Stirring speed, controlled by a magnetic stirrer, impacts the gas-liquid mass transfer rate. Increased liquid phase stirring speed ensures faster species transport to the gas phase, with a diminishing effect beyond 900 rpm. TiO2 photocatalyst mass concentration influences the available total active surface and irradiation absorbance in the photoreactor volume. Optimal product yields were observed at the lowest tested photocatalyst concentration (0.5 g center dot L-1), indicating improved irradiation distribution and reduced particle agglomeration, resulting in higher available active surface for the reaction. The calculation model successfully predicted product yields even with lower photocatalyst concentration of 0.25 g center dot L-1, with marginal increases in predicted yields. These findings provide valuable insights for scaling up and optimizing the CO2 photocatalytic reduction process, offering a foundation for future research.
Fast bicriteria streaming algorithms for submodular cover problem under noise models
(Elsevier, 2024) Nguyen, Bich-Ngan T.; Pham, Phuong N. H.; Pham,Canh V.; Snášel, Václav
The Submodular Cover (SC) problem has attracted the attention of researchers because of its wide variety of applications in many domains. Previous studies on this problem have focused on solving it under the assumption of a non-noise environment or using the greedy algorithm to solve it under noise. However, in some applications, the data is often large-scale and brings a noisy version, so the existing solutions are ineffective or not applicable to large and noisy data. Motivated by this phenomenon, we study the Submodular Cover under Noises (SCN) problem and propose two efficient streaming algorithms, which provide a solution with theoretical bounds under two common noise models, multiplicative and additive noises. The experimental results indicate that our proposed algorithms not only provide the solution with a high objective function value but also outperform the state-of-the-art algorithm in terms of both the number of queries and the running time.
Influence of air spring parameters to tyre wear
(Inderscience Enterprises Ltd, 2024) Mikula, Luboš; Famfulík, Jan; Richtář, Michal; Šarkan, Branislav
Context. When using CNG buses, abnormal tyre wear started to occur. Objectives. To identify possible causes of this phenomenon, verify its impact by practical experiment and suggest solutions. Methods. During the experiment, three same vehicles were set up with different air spring settings, resulting in different clear heights of 325 mm, 335 mm, 345 mm. After approx. 45,000 km, tyre wear was examined, tyre defects were measured and compared. Results. Vehicle most affected by heel-toe wear was one with the highest clear height of 345 mm. Higher clear height negatively influences tyre wear, but it is clear that other causes are included in this problem. Conclusions. Experiment and calculations affirmed that the primary cause of the tyre wear irregularities is vibrations applied to tyres caused by added weight. This theory is confirmed by an investigation more prescribed in the introduction section.
Transverse cracking signal characterization in CFRP laminates using modal acoustic emission and digital image correlation techniques
(Elsevier, 2024) Šofer, Michal; Cienciala, Jakub; Šofer, Pavel; Paška, Zbyněk; Fojtík, František; Fusek, Martin; Czernek, Pavel
The process of formation and subsequent propagation of transverse cracks in 90 degrees plies of carbon-fiber laminated composites was studied using modal acoustic emission approach and digital image correlation techniques. The results from modal acoustic emission approach, which included a newly developed processing tool for acoustic emission waveforms, provided information for identification and subsequent characterization or localization of signals originating from transverse cracking by analysis of the separated flexural and extensional Lamb wave modes in terms of their modal parameters. The digital image correlation method served as a verification tool of the acoustic emission data outputs in the terms of activity of significant localized events originating from the formation of the transverse crack in the 90oply. This made it possible to specify more locally the accompanying activity belonging to the formation or propagation of the magistral transverse crack. The manuscript also presents results related to the evolution of flexural/extensional wave modal parameters as the function of loading force for both [0/0/0/90]S and [90/0/0/0]S panels. It can be concluded that the detection of transverse cracks requires the need for applying a more complex acoustic emission data analysis methodology, while the standard parametric analysis, including the waveform peak frequency, is not sufficient. The presented methodology may serve as a basis for development of robust analysis tool capable of detecting the investigated phenomena.
Evaluation of safe operating envelope for CO2 injection under uncertain rock mechanical parameters and earth stresses
(Elsevier, 2024) Nermoen, Anders; Shchipanov, Anton; Porzer, Michal Matloch; Šancer, Jindřich; Berenblyum, Roman
Carbon Capture and Storage (CCS) is a pre-requisite to decarbonize CO2 emissions from industrial sectors and as an industry capable of compensating for hard-to-abate emissions in a net zero scenario. A method was developed to evaluate the geomechanical constraints and safe operating envelope as function of pore pressure and temperature. The probability of failure was estimated from uncertain input stiffness and strength data, and as cooling and re-pressurization shifts the in-situ effective stresses, the safe operating envelope was determined, here given by pressure and temperature. Onshore storages nearby industrial clusters enable energy and cost-effective handling of CO2. In the SouthEastern European region, onshore depleted oil and gas fields located nearby high-emitting industries may developed into CO2 storages. This paper describes a method for determining maximum fluid pressure as function of temperature from geomechanical restrictions. The method was employed on a practical example used to evaluate the safe operation envelope for a pilot CO2 injection site into a depleted onshore naturally fractured carbonate oil and gas field. The tool uses Monte Carlo simulations to perform geomechanical stability analyses by sampling from the inherent uncertainty of the input parameters to probability of failure as function of pressure and temperature. The risk of re-opening natural fractures, induced fracturing and fault reactivation are evaluated so the safe operating envelope can be obtained. The uncertainty of the input parameters is thus directly reflected in the safe operating envelope - thus providing an effective communication of value information to external stake holders when maturing a CO2 storage pilot.
Laboratory experiments and geochemical modeling of gas–water–rock interactions for a CO2 storage pilot project in a carbonate reservoir in the Czech Republic
(MDPI, 2024) Ličbinská, Monika; Labus, Krzysztof; Klempa, Martin; Matýsek, Dalibor; Vašek, Milan
The aim of this study was to characterize the influence of CO2 in geological structures on mineralogical changes in rocks and assess the sequestration capacity in mineral form and solution of a potential pilot storage site in the Czech Republic. Rock samples from a dolomite reservoir and the overburden level, as well as the corresponding pore water, were used. The most important chemical process occurring in the reservoir rock is the dissolution of carbonate minerals and feldspars during the injection of CO2 into the structure, which increases the porosity of the structure by approximately 0.25 percentage points and affects the sequestration capacity of the reservoir rock. According to the results of geochemical modeling, the secondary carbonate minerals (dolomite, siderite, and ephemeral dawsonite) were present only during the first 50 years of storage, and the porosity at this stage decreased by 1.20 pp. In the caprocks, the decomposition of K-feldspar and calcite resulted in an increase in porosity by 0.15 percentage points at the injection stage only, while no changes in porosity were noted during storage. This suggests that their insulation efficiency can be maintained during the injection and post-injection periods. However, further experimental research is needed to support this observation. The results of this study indicate that the analyzed formation has a low potential for CO2 sequestration in mineral form and solution over 10,000 years of storage, amounting to 5.50 kg CO2/m(3) for reservoir rocks (4.37 kg CO2/m(3) in mineral form and 1.13 kg CO2/m(3) in dissolved form) and 3.22 kg CO2/m(3) for caprock rocks (3.01 kg CO2/m(3) in mineral form and 0.21 kg CO2/m(3) in dissolved form). These values are lower than in the case of the depleted Brodsk & eacute; oil field, which is a porous reservoir located in the Moravian part of the Vienna Basin.
Unveiling solitons and dynamic patterns for a (3+1)-dimensional model describing nonlinear wave motion
(AIMS Press, 2024) Riaz, Muhammad Bilal; Kazmi, Syeda Sarwat; Jhangeer, Adil; Martinovič, Jan
In this study, the underlying traits of the new wave equation in extended (3 +1) dimensions, utilized in the field of plasma physics and fluids to comprehend nonlinear wave scenarios in various physical systems, were explored. Furthermore, this investigation enhanced comprehension of the characteristics of nonlinear waves present in seas and oceans. The analytical solutions of models under consideration were retrieved using the sub -equation approach and Sardar sub -equation approach. A diverse range of solitons, including bright, dark, combined dark -bright, and periodic singular solitons, was made available through the proposed methods. These solutions were illustrated through visual depictions utilizing 2D, 3D, and density plots with carefully chosen parameters. Subsequently, an analysis of the dynamical nature of the model was undertaken, encompassing various aspects such as bifurcation, chaos, and sensitivity. Bifurcation analysis was conducted via phase portraits at critical points, revealing the system's transition dynamics. Introducing an external periodic force induced chaotic phenomena in the dynamical system, which were visualized through time plots, twodimensional plots, three-dimensional plots, and the presentation of Lyapunov exponents. Furthermore, the sensitivity analysis of the investigated model was executed utilizing the Runge-Kutta method. The obtained findings indicated the e fficacy of the presented approaches for analyzing phase portraits and solitons over a wider range of nonlinear systems.
Experimental variable band hybrid current mode control for high power high frequency inverter in electro surgical applications
(IEEE, 2024) Mohsin Rafiq, Muhammad; Ullah, Nasim; Prokop, Lukáš; Mišák, Stanislav
Electrosurgical generators (ESGs) are vital during medical operations, providing high-frequency electrical currents for cutting tissue and coagulation in surgery. Maintaining precise control over output power is challenging due to variable tissue loads. Inconsistent regulation can lead to undesirable surgical outcomes. This paper addresses this challenge through a novel Variable band hybrid current mode control (VBHCMC) technique. The study explores the limitations of existing approaches, such as peak current mode control (PCMC), emphasizing the need for improving control methodologies. The proposed VBHCMC method ensures stable output power, addressing issues associated with PCMC. It dynamically adapts the hysteresis band for variable load impedances, enhancing stability. The significance of this approach lies in its ability to combine the benefits of peak and valley current mode controls while maintaining a nearly constant switching frequency, significantly reducing steady-state errors. Results demonstrate significant reduction in steady-state errors compared to conventional PCMC. The proposed controller provides an effective solution to challenges faced in regulating output power during surgical procedures, enhancing safety and precision. The results have been verified in the MATLAB/Simulink environment, Processor-in-Loop (PIL) simulation in PSIM and using hardware validation.
Ex situ Raman mapping of LiMn2O4 electrodes cycled in lithium-ion batteries
(American Chemical Society, 2024) Buchberger, Dominika A.; Hamankiewicz, Bartosz; Michalska, Monika; Głaszczka, Alicja; Czerwiński, Andrzej
In this study, we focus on the large-scale ex situ Raman mapping of LiMn2O4 (LMO) electrodes maintained at varying states of charge. A comprehensive statistical analysis has been conducted at an area of ca. 3660 mu m(2) on more than 3100 collected spectra for each LMO electrode sample. High-definition ex situ Raman maps provide profound insight into the lithiation process, offering an additional perspective on the mechanism of LMO intercalation. These maps clearly depict the coexistence of two phases, with evident phase transitions and state-of-charge gradients. The set of spectra with various state-of-charge has been successfully deconvoluted taking into account the two-phase character of the ongoing reaction. In addition, we performed the study on the samples operated for 50 cycles at the high C-rates and tracked their delithiation state and impurity formation. This technique serves as a complementary visualization and analytical tool alongside other bulk-type methods employed in battery diagnostics. Importantly, this ex situ Raman mapping approach is applicable to any electrode material exhibiting a Raman response.

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