Hrčak - Portal of scientific journals of Croatia
Not a member yet
321498 research outputs found
Sort by
Fast and Accurate Design of BLDC Motors Using Bayesian Neural Networks
No full textBrushless direct current (BLDC) motors are gaining popularity over traditional direct current (DC) motors due to their higher efficiency, compact size, and precise control capabilities. This study proposes a fast and accurate approach to BLDC motor design using a Bayesian neural network (BNN). The BNN, a specialized form of the multi-layer perceptron (MLP), offers strong resistance to overfitting and performs effectively with noisy or limited datasets, making it well-suited for complex motor design problems. In the proposed method, the BNN is applied within an inverse modeling framework to map desired motor performance parameters to the corresponding design variables. A dataset for an outer-rotor BLDC motor—containing both design parameters and the resulting output torque—is generated through finite element analysis (FEA). Finally, a demonstration of BLDC motor design using the BNN validates the effectiveness of the proposed approach
Quality of Forest Planting Material – Importance, Description and Methodology
No full textŠumski reprodukcijski materijal (ŠRM) ključan je u svim šumskouzgojnim aktivnostima. Međutim, klimatske promjene dovode do promjena u pogodnosti staništa za pojedine šumske vrste što otežava planiranje i provođenje šumskouzgojnih aktivnosti. Stoga, da bi uspješno planirali i provodili šumskouzgojne aktivnosti potreban je kvalitetan ŠRM, posebice visokokvalitetne šumske sadnice prilagođene uvjetima staništa. Kvaliteta šumskih sadnica može se utvrditi raznim morfološkim i fiziološkim svojstvima, međutim, najvažnija su ona koja omogućuju preživljenje i rast šumske sadnice u sadašnjim, ali i budućim uvjetima staništa. Cjelokupnim pregledom i analizom dostupnih publikacija uočava se nedostatak recentnih znanstvenih publikacija i aktivnije znanstveno-istraživačke djelatnosti na temu kvalitativnih svojstava šumskih sadnica. K tome, utvrđivanje kvalitete šumskih sadnica na temelju morfoloških i fizioloških svojstava prilikom stavljanja na tržište kod većine vrsta nije obuhvaćeno zakonskim okvirima, stoga je cilj ovog rad I.) utvrditi morfološka i fiziološka svojstva šumskih sadnica koja ukazuju na njihovu kvalitetu i II.) dati opće preporuke za rasadničku proizvodnju šumskih sadnica ususret klimatskim promjenama. Provedenim istraživanjem utvrđeno je da kvaliteta šumskih sadnica zahtjeva integraciju morfoloških i fizioloških svojstava, pri čemu su izdvojena ona najvažnija za preživljenje i rast sadnice na terenu. Od morfoloških svojstava izdvajaju se: visina, promjer stabljike, odnos visine i promjera stabljike, kvaliteta korijenskog sustava i odnos korijenskog sustava i izbojaka. Fiziološka svojstva su: otpornost na hladnoću, otpornost na sušu i stanje hranjiva u tkivu šumskih sadnica. Za svako svojstvo dan je opis njegove važnosti za preživljenje i rast sadnice na terenu te način njegova utvrđivanja. Ističe se važnost unaprijeđena proizvodnog programa rasadničke proizvodnje i potrebitost staništu prilagođenih šumskih sadnica ususret novim izazovima koji stoje pred šumarskim sektorom u Republici Hrvatskoj. Iako teško predvidive, klimatske promjene i ugroze su neizbježne, stoga je kvalitetan i raznolik proizvodni program rasadnika šumskih sadnica u Republici Hrvatskoj potrebniji nego ikad kako bi se povećala otpornost šumskih sastojina na trenutne i predstojeće ugroze. Proizvodni program treba prepoznati trenutne i predstojeće obaveze kao i međunarodna kretanja sadnog materijala, recentne znanstvene spoznaje, potrebe praktičnog šumarstva i ostalih grana privrede, predviđanje promjena u pogodnosti staništa za šumske vrste te pronalaženje suvremenih rješenja prilagodbe šuma na predstojeće ugroze i izazove.Forest reproductive material (FRM) is essential for silvicultural activities. Climate change impacts site suitability for certain species, complicating the planning and execution of activities. High-quality FRM, especially seedlings adapted to local conditions, is crucial for planting to be effective. Seedling quality can be determined by various attributes, but the most important attributes are those that enable the survival and growth of forest seedlings in current and future site conditions. A review of current publications shows a lack of recent scientific studies and active research on the qualitative properties of forest seedlings. Additionally, there is insufficient legal framework for assessing seedling quality based on their morphological and physiological attributes when marketed for most species. The aim of this paper is I) to determine the morphological and physiological attributes of forest seedlings that affect their quality, and II) to provide general recommendations for nursery production of forest seedlings in the face of climate change. The research determined that the quality of forest seedlings requires the integration of morphological and physiological attributes, emphasizing the most important ones for the survival and growth of seedlings in the field. For each attribute, its significance for seedling survival and growth in the field is described, along with the determination method. Nursery production programs and general recommendations for producing forest seedlings due to climate changes are emphasized. While difficult to predict, threats are inevitable; therefore, a quality production program is more essential than ever
On b-repdigits as products or sums of Fibonacci, Pell, balancing and Jacobsthal numbers
No full textLet be an integer. In this paper, we study the repdigits in base that can be expressed as sums or products of Fibonacci, Pell, balancing and Jacobsthal numbers. The proofs of our main theorems use lower bounds for linear forms in logarithms of algebraic numbers and a version of the Baker-Davenport reduction method
An Unusual Relationship Between Auditory Hallucinations, Alcohol Drinking, and Alcohol-Induced Premature Liver Damage in a Patient With Schizophrenia: a Case Report
No full textAim: This case report explores the relationship between psychotic symptoms and excessive alcohol consumption in schizophrenia, examining its role in self-medication, premature liver damage, and treatment challenges. Case report: We describe a 31-year-old male with schizophrenia, who was nonadherent to antipsychotic treatment, and who repeatedly manifested excessive alcohol consumption during the exacerbations of psychotic symptoms, claiming that his alcohol drinking was for the purpose of self-medicating for auditory hallucinations. Despite temporary perceived relief, the patient developed severe alcohol-related liver damage, including alcoholic hepatitis and portal hypertension, at a remarkably early age. This case challenges the classical self-medication hypothesis, as alcohol use likely worsened both psychiatric and physical outcomes. Conclusions: This report highlights the complex relationship between psychosis and alcohol misuse, underscoring the need to explore alternative mechanisms linking auditory hallucinations to alcohol consumption. It also emphasizes early recognition of alcohol-related liver damage in schizophrenia. When liver function is impaired, careful selection of antipsychotic treatment is critical. The atypical antipsychotic amisulpride, with its minimal hepatic metabolism, appears to be a promising option for controlling psychotic symptoms and reducing alcohol cravings in such cases
A Diode-Enhanced Equivalent Circuit and SVM-Based Framework for Accurate Simulation of Battery Discharge under Variable Currents
No full textAccurate simulation of battery discharge under variable current conditions is essential for improving the performanceand safety of new energy vehicles. Conventional equivalent circuit models struggle to capture voltage hysteresis, leading to cumulative errors in state of charge (SOC) estimation. This paper proposes a diode-incorporated dual-polarization equivalent circuit model that simulates voltage delay behaviour during charge-discharge transitions. A support vector machine (SVM) model is employed to estimate open-circuit voltage (OCV), which is combined with the ampere-hour integration method for SOC prediction. The proposed framework is further validated against the pseudo two-dimensional (P2D) electrochemical model using ion and charge conservation laws. Simulation experiments on a lithium-ion battery model under representative driving conditions demonstrate that the diode-enhanced model reduces hysteresis-induced errors by 32.7%, with SOC estimation errors within ±1.5%. The discharge duration at 75% initial capacity is shortened by 35% compared to full capacity, and discharge efficiency varies linearly with driving speed. These results confirm that the proposed hybrid electrochemical-circuit-machine learning framework provides a reliable method for analyzing battery discharge behaviour under dynamic currents
The Late Badenian shallow-water marine deposits of the southwestern Dacian Basin, Serbia
No full textThis study presents late Badenian (= early Serravallian) shallow-water marine environments in the Veliki Izvor and Nikoličevo areas in eastern Serbia. Biostratigraphically, the Upper Badenian Bulimina-Bolivina Zone and Ammonia/Elphidium impoverishment Ecozone are documented and correlated with the M6 zone, characterized by the presence of Orbulina suturalis. The Upper Badenian coarse- to medium-grained marine clastics transgressively overlie older Cretaceous flysch, carbonates, and volcanoclastics as well as early Miocene continental deposits. Comparative sedimentological and palaeontological analyses of the two outcrops reveal different depositional environments, water level fluctuation, and redepo-sitional processes. The Veliki Izvor area represents a shallow-marine, tidally influenced system, whereas Nikoličevo is characterized by a more proximal, fluviodeltaic setting with evidence of episodic carbonate influx. Numerous well-preserved fossils of corals, bivalves, and gastropods, along with poorly preserved foraminifera and ostracods, indicate a mar-ginal marine, well- oxygenated environment of normal salinity. Benthic foraminiferal assem-blages (dominated by Elphidium–Biasterigerina–Ammonia specimens) suggest deposition in a well-oxygenated inner to middle shelf setting. A higher proportion of euryhaline genera such as Elphidium and Ammonia points to episodic freshwater inflows into the marine en-vironment. Rare occurrences of Bolivina and Heterolepa specimens indicate brief periods of low oxygen conditions, while the Elphidium–Biasterigerina assemblage reflects recovery phases with renewed vertical water circulation and bottom water oxygenation. Low-diversi-ty ostracod assemblages further support the shallow marine environments. These findings contribute to a better understanding of marginal Miocene basins in southeastern Europe and highlight the complexity of shallow-water marine depositional systems
Mobilno-protetska terapija pacijenata s nezavršenim rastom i razvojem
No full textMobilna protetska terapija kod pacijenata s nezavršenim rastom i razvojem zahtijeva multidisciplinarni pristup jer su konvencionalne protetske mogućnosti često ograničene. Genetski sindromi kao ektodermalna displazija, Downov sindrom, Turnerov sindrom i Apertov sindrom česti su uzroci većih bezubih područja ili potpune bezubosti kod mladih pacijenata. Mobilne proteze, uključujući djelomične i potpune proteze te pokrovne proteze, nude značajne prednosti nad fiksnim konstrukcijama: neinvazivnost, mogućnost adaptacije prilikom rasta i razvoja pacijenta te brzu izradu i popravak. Indikacije uključuju veće bezube raspone, kraće bezube raspone prije skoka rasta, skraćene zubne lukove, potpunu bezubost te planiranje budućih implantoprotetskih terapija. Važne kontraindikacije su pomičnost zubi, nemogućnost održavanja oralne higijene i potreba za ortodontskim pomacima. Potpune proteze su često jedina opcija za potpuno bezube pacijente, ali zahtijevaju česte adaptacije (svakih šest mjeseci) i izradu novih proteza svakih četiri do šest godina. Djelomične proteze lakše se prilagođavaju i primjenjuju se u ranoj mješovitoj denticiji, dok se pokrovne proteze s teleskopskim krunama preporučuju u kasnoj mješovitoj i trajnoj denticiji. Uspješna terapija ovisi o dobrom planiranju, redovitim kontrolama, čuvanju preostalih zubi i suradnji pacijenta u održavanju oralne higijene
What motivates travellers to visit low-carbon destinations? empirical evidence from Thailand
No full textPurpose – Despite growing interest in low-carbon tourism research, few studies have
explored travellers’ motivations for choosing low-carbon destinations, particularly through
the push-pull theory. Research indicates that motivations for environmental tourism may
vary across cultures due to multiple factors, necessitating a context-specific investigation
and diverse research approaches. This study addresses these gaps by applying the push-pull
motivation theory to examine travel motivations in the context of low-carbon destinations in
Thailand. A thorough understanding of tourist motivations across different cultural settings is
essential for advancing theoretical knowledge and promoting sustainable tourism practices.
Methodology/Design/Approach – Adopting a naturalistic inquiry approach, data were collected
through semi-structured interviews and analysed using thematic analysis. Participants were
selected through purposive sampling.
Findings – The study identifies three push factors: good environment seeking, learning &
knowledge seeking, and rest & escape; and six pull factors: attractive destination attributes,
interesting tourist activities, appealing communication, convenient accessibility, environmentally
friendly service providers, and environmental management appeals. The study reveals both
common and new push and pull factors related to low-carbon travel motivations.
Originality of the research – This study contributes to the push-pull motivation theory
by introducing good environment seeking as a distinct push factor. It further refines the
conceptualisation of pull factors by integrating sustainability practices with traditional
destination attributes, thereby enhancing the theoretical understanding of what makes lowcarbon destinations attractive
