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General position problems in strong and lexicographic products of graphs
No full textOuter, dual, and total general position sets are studied on strong and lexicographic products of graphs. Sharp lower and upper bounds are proved for the outer and the dual general position number of strong products and several exact values are obtained. For the lexicographic product, the outer general position number is determined in all the cases, and the dual general position number is established in many cases. The total general position number is determined for both products. Along the way some results on outer general position sets are also derived
Investigation of aircraft cabin lighting design using response surface method
No full textThis paper presents a simulation design method for optimizing the lighting system in the aircraft cabin to improve the emotional experience of passengers. First, based on the theory of Kansei Engineering, a novel evaluation protocol is created that fuses multisource heterogeneous data. The main objective of this method is to extract the most important influencing parameters, taking into account various factors and to investigate passengers emotional requirements in the ”human-machine-environment” system such as, in the aircraft cabin. Second, the within response surface method calculates a recommended interval and optimal solution by mapping between lighting impact factor and passengers’ emotional value, resulting in a data reference range for cabin lighting. Finally, the recommended parameters for aircraft cabin lighting are visualized with the professional lighting software Dialux. The results show that this study offers an effective approach to improving the comfort of aircraft cabin lighting. Consequently, this could increase the quality of flight services, and the methodological approach could also be applicable to the optimization of other cabin lighting
Researching the influence of thermomechanical loading on a bonded joint
No full textUporabiti želimo za nas novo silikonsko lepilo, ki bo na aluminijasto hladilo pritrjevalo vezje na bakreni plošči. Ključne lastnosti lepila so, da dobro prevaja toploto, je električno izolativno in ima dobre mehanske lastnosti. Z nalogo smo želeli ugotoviti, ali termomehansko obremenjevanje, ki mu bo izdelek podvržen, vpliva na lepljen spoj oz. na lepilo. Zasnovali smo preizkušanec s tremi različnimi debelinami plasti lepila, pripravili preizkuševališča za merjenje ključnih lastnosti ter preizkušanec izpostavili cikličnim termomehanskim obremenitvam ter podatke statistično ovrednotili. Ugotovitve kažejo, da termomehansko staranje vpliva na lastnosti lepila, pri čemer ima vpliv tudi debelina nanosa lepila. Večina lastnosti se nekoliko poslabša, v nekaterih primerih pa se celo izboljšajo. S tem lahko potrdimo, da je lepilo za izbrano nalogo zelo primerno.We want to use a new silicone adhesive that will bond a circuit board on a copper plate to an aluminum heat sink. The key properties of the adhesive are that it conducts heat well, is electrically insulating and has good mechanical properties. With the task, we wanted to determine whether the thermomechanical loading to which the product will be subjected affects the bonded joint or the adhesive. We designed a test specimen with three different adhesive layer thicknesses, prepared test sites for measuring key properties, exposed the test specimen to cyclic thermomechanical loads and statistically evaluated the data. The findings show that thermomechanical aging affects the properties of the adhesive, with the thickness of the adhesive layer also having an impact. Most properties deteriorate slightly, and in some cases they even improve. This confirms that the adhesive is very suitable for the selected task
Proximal humerus fractures in the elderly work up, classifications and fracture biomechanics
No full textThis article discusses fractures of the upper third of the humerus in elderly patients within the context of diagnostic evaluation, fracture classification, biomechanics, and fracture occurrence, including osteoporosis. The shoulder joint is composed of the proximal humerus and the glenoid of the scapula. Very important factors for fracture incidence and patterns are osteoporosis and distribution of bone tissue and bone density in the proximal humerus. Most fractures are caused by fall from standing height. Parts of diagnostic work-up and management plans are clinical examination, different imaging modalities and classification systems
On properties and numerical computation of critical points of eigencurves of bivariate matrix pencils
No full textWe investigate critical points of eigencurves of bivariate matrix pencils . Points for which form algebraic curves in and we focus on points where . Such points are referred to as zero-group-velocity (ZGV) points, following terminology from engineering applications. We provide a general theory for the ZGV points and show that they form a subset (with equality in the generic case) of the 2D points , where is a multiple eigenvalue of the pencil , or, equivalently, there exist nonzero and such that , , and . We introduce three numerical methods for computing 2D and ZGV points. The first method calculates all 2D (ZGV) points from the eigenvalues of a related singular two-parameter eigenvalue problem. The second method employs a projected regular two-parameter eigenvalue problem to compute either all eigenvalues or only a subset of eigenvalues close to a given target. The third approach is a locally convergent Gauss–Newton-type method that computes a single 2D point from an inital approximation, the later can be provided for all 2D points via the method of fixed relative distance by Jarlebring, Kvaal, and Michiels. In our numerical examples we use these methods to compute 2D-eigenvalues, solve double eigenvalue problems, determine ZGV points of a parameter-dependent quadratic eigenvalue problem, evaluate the distance to instability of a stable matrix, and find critical points of eigencurves of a two-parameter Sturm–Liouville problem
A hybrid radial basis function-finite difference method for modelling two-dimensional thermo-elasto-plasticity, part 3: application to thermo-mechanical modelling of continuous casting of steel billets
No full textThis paper, Part 3 of a series, extends the previously developed strong-form hybrid radial basis function-finite difference (RBF-FD) method to model the thermomechanics of continuous casting (CC) of steel. Part 1 introduced the method for non-linear thermomechanics, and Part 2 applied it to the cooling of steel bars on a cooling bed. Here, a one-way coupled thermo-mechanical slice model is developed, where the temperature field provides thermal loading for the mechanical analysis. The previously introduced 2.5D formulation is adapted to include strand straightening. A visco-plastic material model, validated in our recent work, is used to describe material behaviour close to the mushy-zone temperatures. The analysis focuses on the solidified part of the strand, while the space discretisation remains constant and liquid-zone results are disregarded. Two hot-tearing criteria—temperature-based and stress-based are implemented and compared with experimental data, showing that the stress-based approach produces more realistic predictions. The influence of electromagnetic stirring, steel grade composition, and casting speed on hot-tearing susceptibility is explored. This study represents the first strong-form RBF-FD solution of CC thermomechanics, demonstrating that the hybrid RBF-FD can efficiently handle complex non-linear thermo-mechanical behaviour and allows for further process optimisation and defect mitigation in industrial CC
Taxonomy, Biostratigraphy, and Palaeoecology of Ostracods from Sarmatian and Pannonian deposits in Eastern Slovenia
No full textDoktorska disertacija obravnava paleontološke, biostratigrafske in paleoekološke raziskave ostrakodnih združb iz badenijskega, sarmatijskega in panonijskega obdobja. V raziskavo je bilo vključenih šest sedimentnih profilov z območja vzhodne Slovenije: Imenska Gorca, Bizeljsko, Sladki Vrh, Cerkvenjak, Miklavž pri Ormožu in Jeruzalem. Skupaj je bilo pridobljenih 256 vzorcev, iz katerih je bilo taksonomsko določenih 129 vrst ostrakodov, pripadajočih 54 rodovom. Na podlagi analize so bile identificirane biocone, in sicer dve na območju Bizeljskega ter štiri na območju Imenske Gorce. Na Bizeljskem sta bili določeni spodnje badenijska biocona Acanthocythereis hystrix – Bythocypris lucida ter zgornje panonijska Bakunella dorsarcuata biocona. Na Imenski Gorci so bile prepoznane zgornje badenijska Carinocythereis carinata – Phlyctenophora farkasi, spodnje sarmatijska Cytheridea hungarica – Aurila mehesi, zgornje panonijski Hemicytheria prisca in Bakunella dorsarcuata bioconi. Paleoekološke interpretacije kažejo na deltno sedimentacijsko okolje z nihajočo slanostjo med morskimi in sladkovodnimi pogoji. Geokemične analize stabilnih izotopov kisika in ogljika ter slednih prvin (Mg, Ca, Sr) v ostrakodnih lupinah dopolnjujejo paleoekološke ugotovitve. Interpretacija temperaturnih podatkov je omejena zaradi majhnega števila vzorcev in prekristalizacije lupin, medtem ko rezultati slednih prvin delno potrjujejo paleoekološke interpretacije. Ti rezultati pomembno prispevajo k razumevanju paleogeografskih in paleookoljskih sprememb v vzhodni Sloveniji v zgornjem miocenu.The doctoral dissertation addresses paleontological, biostratigraphic, and paleoecological investigations based on ostracod assemblages from the Badenian, Sarmatian, and Pannonian time intervals. The study encompasses six sedimentary sections from eastern Slovenia: Imenska Gorca, Bizeljsko, Sladki Vrh, Cerkvenjak, Miklavž pri Ormožu, and Jeruzalem. A total of 256 samples were collected, from which 129 ostracod species belonging to 54 genera were taxonomically identified. Based on the analyses, biozones were identified, including two from the Bizeljsko area and four from Imenska Gorca. In Bizeljsko, the Lower Badenian Acanthocythereis hystrix – Bythocypris lucida biozone and the Upper Pannonian Bakunella dorsarcuata biozone were determined. At Imenska Gorca, the Upper Badenian Carinocythereis carinata – Phlyctenophora farkasi, Lower Sarmatian Cytheridea hungarica – Aurila mehesi, Upper Pannonian Hemicytheria prisca and Bakunella dorsarcuata biozones were recognized. Paleoecological interpretations indicate a deltaic depositional environment with fluctuating salinity between marine and freshwater conditions. Geochemical analyses of stable oxygen and carbon isotopes, as well as trace elements (Mg, Ca, Sr) from ostracod shells, complement the paleoecological findings. Interpretation of temperature data derived from oxygen isotopes is limited due to the small sample size and recrystallization of shells, whereas trace element results partially confirm the paleoecological interpretations. These findings significantly contribute to the understanding of paleogeographic and paleoenvironmental changes in eastern Slovenia during the Late Miocene
Administration route and trial repetition shape the effects of a commercial synbiotic on broiler production performance, cecal microbiota and pathogen colonization
No full textCampylobacter and Salmonella are leading causes of foodborne bacterial enteritis, with poultry meat being an important source. This longitudinal field study evaluated the impact of the commercial synbiotic PoultryStar, administered via water or feed, on broiler production performance, gut colonization with Campylobacter jejuni and Salmonella Infantis, and cecal microbiota. Two large food business operators were included in the study, with two independent trials conducted at each. A significantly higher European efficiency factor was observed when synbiotic was supplemented in water rather than in feed, although the effect did not differ from the control group. Body weight also tended to increase with synbiotic supplementation in water, although the effect was inconsistent across farms. Feed supplementation significantly reduced colonization of broilers with S. Infantis, whereas no effect was observed regarding C. jejuni. However, two bacterial taxa potentially contributing to the colonization resistance against C. jejuni were identified, belonging to the genus Lactobacillus and an unclassified representative of Bacteroidota. Administration of the synbiotic significantly influenced cecal microbiota, with outcomes depending on the administration route but, importantly, varying significantly between food business operators and even trial repetitions. Overall, PoultryStar exerted limited effects on pathogen control and production performance, while external factors such as administration route and trial repetition strongly modulated outcomes. Our findings highlight the need for repeated, farm-level evaluations and tailored probiotic strategies to optimize broiler health