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Nauka – Technika – Technologia : seria wydawnicza AGH. Tom 10
No full textThe paper presents a description of the construction of an analog audio effect using biosignals recorded from the human scalp to modulate sound. The biosignals included electroencephalographic waves narrowed to the Alpha brainwave band, as well as electrooculographic waves within the same band. A phaser effect was chosen, which modifies input signals based on changing the center frequency of notch filters. The device was designed to operate in two modes. In the first mode, EEG (electroencephalographic) and EOG (electrooculographic) waves were directly used to control the filters affecting the sound. In the second mode, modulation was carried out using a triangular signal obtained from a voltage-controlled oscillator, to which the envelope of the recorded waves was applied. The effect was tested during an electroencephalograph examination, and the degree of user control over its parameters was determined through the analysis of the obtained spectrograms.W pracy przedstawiono opis budowy analogowego efektu audio wykorzystującego biosygnały zarejestrowane na skórze głowy człowieka do modulacji dźwięku. W zakres biosygnałów wchodziły fale elektroencefalograficzne zawężone do pasma fal mózgowych alfa, a także elektrookulograficzne zawierające się w tym samym paśmie. Wybrany został efekt typu phaser modyfikujący sygnały wejściowe w wyniku zmiany częstotliwości środkowej filtrów pasmowo- -zaporowych. Urządzenie skonstruowano tak, by funkcjonowało w dwóch trybach. W pierwszym z nich fale EEG (elektroencefalograficzne) i EOG (elektrookulograficzne) były wykorzystywane bezpośrednio do sterowania filtrami wpływającymi na dźwięk. W drugim – modulacja odbywała się z wykorzystaniem sygnału trójkątnego uzyskanego z generatora przestrajanego napięciem, na którego wejście podano obwiednię zarejestrowanych fal. Efekt został przetestowany podczas badania elektroencefalografem, zaś stopień kontroli użytkownika nad jego parametrami został określony podczas analizy uzyskanych spektrogramów.Krakówrozdziałwersja wydawnicz
Nauka – Technika – Technologia : seria wydawnicza AGH. Tom 9
No full textThe advent of 3D printing technology in the prosthetics sector makes it possible to accurately reproduce a patient’s specific case of missing teeth, without generating material waste. Due to its precision and accuracy, the technique of selective fusion of metal powders DLMS (direct metal laser sintering) is increasingly being used. The research that was carried out within the scope of the presented work consisted in the evaluation of the influence of 3D printing parameter variation and heat treatment on the properties of a dental Co-Cr alloy with tungsten and molybdenum micro-additives. The metallic specimens used in the study were fabricated in the prosthetic laboratory by a dental technician using DMLS technology from Ador’s Co-Cr-W-Mo Adorbond CC metallic powder with a variable 3D printing parameter, i.e. layer printing thicknesses of 20 μm and 30 μm, respectively. The samples were then heat treated (annealed at 1150°C for 1 h). In this study, microstructural analysis using light microscopy (LM) and scanning electron microscopy (SEM) was compared and performed along with microanalysis of the chemical composition using energy-dispersive spectroscopy (EDS) for all the tested samples produced with print layer thicknesses of 20 and 30 μm before and after heat treatment.Zastosowanie technologii druku 3D w sektorze protetycznym umożliwia dokładne odwzorowanie konkretnego przypadku braków uzębienia u pacjenta bez generowania odpadów materiałowych. Dzięki precyzji i dokładności coraz częściej stosowana jest technika selektywnego stapiania proszków metali DLMS (direct metal laser sintering). Badania naukowe wykonane w ramach prezentowanej pracy polegały na ocenie wpływu zmienności grubości warstwy drukowanych próbek (odpowiednio 20 μm i 30 μm) oraz późniejszej obróbki cieplnej na własności dentystycznego stopu Co-Cr z mikrododatkami wolframu i molibdenu. Wykorzystane do badań próbki metaliczne zostały wykonane w pracowni protetycznej przez technika protetyka w technologii DMLS z proszku metalicznego Co-Cr-W-Mo Adorbond CC firmy Ador ze zmiennym parametrem druku 3D, tj. wysokością druku warstwy odpowiednio 20 μm i 30 μm. Kolejno próbki zostały poddane obróbce cieplnej (wyżarzaniu w 1150°C przez 1 h). W pracy dokonano analizy porównawczej badanych próbek otrzymanych techniką addytywną (DLMS) z grubością warstwy druku 20 μm i 30 μm przed obróbką cieplną i po niej. Badania wykonano z wykorzystaniem mikroskopii świetlnej (LM) oraz elektronowej mikroskopii skaningowej (SEM) wraz z mikroanalizą składu chemicznego z zastosowaniem spektroskopii energodyspersyjnej (EDS), dodatkowo badania uzupełniono o pomiary twardości.Krakówrozdziałwersja wydawnicz
Biomass & Bioenergy
No full textThe management of energy contained in waste is an important research topic. Among many high-energy wastes, pellets are produced from refuse-derived fuels (RDF) and lignocellulosic biomass. This study investigated hightemperature pyrolysis (800 °C) of biomass and RDF pellets. Experiments were conducted in two reactors: i) on a microscale (thermogravimetric analysis) and ii) on a laboratory scale (fixed-bed reactor) to investigate the yields of the products (char, liquid fraction, and gas) and to characterise products toward their further application. The RDF char contained less carbon than the material before pyrolysis. The carbon content of the biomass char was 90%, almost twice that of the raw material. The biomass and RDF chars were chemically and physically activated to increase their specific surface areas. The chemically activated biomass char had a sorption capacity of 156.2 mg/CO2 at 25 °C and 0.1 MPa. The kinetics of CO2 sorption were also examined, and the maximum uptake was observed after 2–3 min. The higher heating value of the liquid phase, including the organic condensed phase, was 28.6 and 25.8 MJ/kg for pyrolysis of biomass and RDF pellets, respectively. The pyrolysis gas composition was analysed separately for the heating and isothermal processes. Due to the high CO, CH4, and H2 contents, the gas from the heating stage was characterised by a much higher heating value.innypostprin
Renewable Energy
No full textThe application of renewable fuels and waste for energy production is crucial environmentally and economically. Co-pyrolysis of biomass and refuse derived fuel (RDF) offers a promising pathway for valuable products that combine various benefits including enhanced energy recovery, waste valorisation, improved product quality, and environmental sustainability. Consideration of specific feedstocks and optimization of process parameters are necessary to maximise the efficiency and effectiveness of the co-pyrolysis process. This work presents investigations of the co-pyrolysis process of lignocellulosic biomass wastes (rye straw and agriculture grass) and RDF. These biomasses ensure efficient decomposition. The RDF, high in carbon (78.5 %) and hydrogen (11.8 %), was predominantly plastic based. Based on Py-GC-MS studies at 600°C, it was observed that the addition of RDF to biomass caused a significant decrease in the share of organic oxygen compounds among the released decomposition products. Laboratory tests were performed in a fixed-bed reactor for raw biomass and RDF and 1:1 and 3:1 biomass to RDF mass ratio. The results demonstrated that the yield of char production decreased with the addition of RDF, which promoted the bio-oil yield. Despite, RDF pyrolysis meets problems, it was proved that co-pyrolysis of biomass and RDF is a good solution for their utilization.postprin
Journal of Casting & Materials Engineering
No full textInorganic binders for sand moulding are currently of high interest due to the need to lessen our environmental impact and emissions. In this study, a heat hardened solid inorganic sodium silicate binder was tested with a 3D printed resin material to see how the use of such a material affected a silica mould’s quality, e.g. surface roughness. Results were compared to moulds made with metallic patterns. The unmodified binder had sticking issues when used with a metallic pattern, resulting in a rough as-moulded surface. Such issues were not seen with the printed resin patterns, also hinting at good performance with binders that contain performance increasing additives. The resin pattern material has a Heat Deflection Temperature (HDT) of 230°C, enabling the use of inorganic binders that require temperatures between 160–200°C to harden and dry. Additive manufacturing of such materials also allows designs for other hardening techniques than furnace heating, such as microwave heating. The moulds hardened with microwaves did not exhibit sticking issues. Additive manufacturing of tooling is a potential source of geometrical variation in final castings and are also studied in this work. In general, switching from traditional sand moulding patterns used with organic binder systems to inorganic systems, the patterns and core boxes need to be replaced by new ones made of a metallic or other heat resistant material. The studied material is a promising option for such a switch, especially when a complex shape enabled by additive manufacturing is also required.Krakówwersja wydawnicz
Computer Methods in Materials Science
No full textTundish is a crucial component just before casting and plays a pivotal role in enhancing the cleanliness and overall homogeneity of the final steel composition. The paper deals with the development of an advanced Computational Fluid Dynamics (CFD) model, specifically focusing on the molten steel flow within the tundish to numerically support its further improvements. A noteworthy addition to the model is the consideration of an electromagnetic stirring device. This device significantly influences steel cleanliness and composition, thereby affecting the final properties of the formed metallic parts in subsequent processing stages. The current investigation presents a comprehensive analysis of flow patterns and stirring energy distributions in relation to active and dead zones within the tundish. Through the developed coupled electromagnetic/fluid dynamic model, the paper demonstrates the feasibility of optimizing mixing processes to control the properties of the final product.Krakówwersja wydawnicz
Geology, Geophysics & Environment
No full textAmong the many factors determining the quality of river waters, the influence of the hyporheic zone (HZ) is gaining in importance. Watercourses that exist in the higher parts of catchments are relatively steep and shallow, and the topography of their valleys activate hyporheic flow. The main goal of this work is to assess the impact of the HZ on the hydrochemical state of the head watercourse of the Malina in the suburbs of the city of Zgierz with the focus on biogenic compounds. The riverbed of this stream was researched across two distinct stretches: erosive and accumulative, which differ in the conditions for the hyporheic zone’s interaction with the riverbed. The nutrients are delivered to the stream mainly in the erosive stretch and are related to the inflow of nutrient-rich groundwater from the urbanised catchment. The pollutants transported down by the stream are then delivered to the HZ in the accumulative stretch, where nitrates are denitrified and phosphates are deposited with the suspension. Ammonium nitrogen, in turn, is introduced into the stream from the HZ as a result of either the process of ammonification of organic matter deposited in sediments or inflow with polluted groundwater. The results indicate that the winter season is the most important period in shaping the interaction of river waters with the underlying hyporheic zone, in which the causal side of the relationship should be associated with the subchannel environment, and the effects are recorded in the river waters.Krakówwersja wydawnicz
Geology, Geophysics & Environment
No full textAbstract: To estimate catchment-scale hydrogeological parameters such as hydraulic conductivity (k) and specific yield (Sy), the streamflow recession analysis method proposed by Brutsaert and Nieber (1977) was used. The analysis employed the technique of fitting a theoretical recession curve to the observed data in which three points of transition between the short- and long-term flow regimes were determined. This method is a simple, fast, and cheap alternative to standard point-based hydrogeological methods using investigations carried out in hydrogeological boreholes. The study area covered the mountainous catchment of the Biała Lądecka River, located in south-western Poland and composed of metamorphic rocks. The hydrogeological environments drained by the Biała Lądecka are two zones, i.e. the zone of weathered covers and rock debris and the zone of fractured rock mass. The k values determined based on the recession analysis were in the boundary zone of the range from to m/s and they represented the upper range of the values reported in the literature (from to m/s). The Sy values at a level of 0.38–1.02%, in turn, entirely fitted the literature data. The results confirm the thesis that the recession method, despite certain limitations in terms of its applicability, can be well adapted to the conditions of a mountainous catchment composed of crystalline rocks where a cool temperate climate prevails.Krakówwersja wydawnicz
Opuscula Mathematica
No full textWe consider an elliptic equation driven by a nonlinear, nonhomogeneous differential operator with nonstandard growth. The reaction has the combined effects of a singular term and of a "superlinear" perturbation. There is no parameter in the problem. Using variational tools and truncation and comparison techniques, we show the existence of at least two positive smooth solutions.Krakówwersja wydawnicz
Computer Science
No full textEvolutionary algorithms mimic some elements of the theory of evolution. The survival of individuals and the ability to produce offspring play significant roles in the process of natural evolution. This process is called natural selection. This mechanism is responsible for eliminating weaker members of the population and provides the opportunity for the development of stronger individuals. The evolutionary algorithm, an instance of evolution in the computer environment, also requires a selection method – a computerized version of natural selection. Widely used standard selection methods applied in evolutionary algorithms are usually derived from nature and prefer competition, randomness, and some kind of “fight” among individuals. But the computer environment is quite different from nature. Computer populations of individuals are typically small, making them susceptible to premature convergence towards local extremes. To mitigate this drawback, computer selection methods must incorporate features distinct from those of natural selection. In the computer selection methods randomness, fight, and competition should be controlled or influenced to operate to the desired extent. This work proposes several new methods of individual selection, including various forms of mixed selection, interval selection, and taboo selection. The advantages of incorporating them into the evolutionary algorithm are also demonstrated, using examples based on searching for the maximum ?-clique problem and traditional Traveling Salesman Problem (TSP) in comparison with traditionally considered highly efficient tournament selection, deemed ineffective proportional (roulette) selection, and other classical methods.Krakówwersja wydawnicz