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Search results for: KNEE BIOMECHANICS
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Coupling between Blood Pressure and Subarachnoid Space Width Oscillations during Slow Breathing
PublicationThe precise mechanisms connecting the cardiovascular system and the cerebrospinal fluid (CSF) are not well understood in detail. This paper investigates the couplings between the cardiac and respiratory components, as extracted from blood pressure (BP) signals and oscillations of the subarachnoid space width (SAS), collected during slow ventilation and ventilation against inspiration resistance. The experiment was performed on...
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Polynomial Chaos Expansion in Bio- and Structural Mechanics
PublicationThis thesis presents a probabilistic approach to modelling the mechanics of materials and structures where the modelled performance is influenced by uncertainty in the input parameters. The work is interdisciplinary and the methods described are applied to medical and civil engineering problems. The motivation for this work was the necessity of mechanics-based approaches in the modelling and simulation of implants used in the repair...
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Determinants of the primary stability of cementless acetabular cup implants: A 3D finite element study
PublicationPrimary stability of cementless implants is crucial for the surgical success and long–term stability. However, primary stability is difficult to quantify in vivo and the biomechanical phenomena occurring during the press–fit insertion of an acetabular cup (AC) implant are still poorly understood. The aim of this study is to investigate the influence of the cortical and trabecular bone Young's moduli Ec and Et, the interference...
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Numerical analysis of lumbar spine injury during road safety barrier collision
PublicationPurpose: Enhancing road safety is a critical goal worldwide, necessitating the development of clear standards for road safety systems. This study focuses on lumbar spine (L-spine) compression injuries during collisions with concrete road safety barriers (RSBs). It aims to analyze internal forces during impact to understand L-spine injury biomechanics in such accidents. Methods: The research included a literature review, analyzing...
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Drill holes decrease cancellous bone strength: A comparative study of 33 paired osteoporotic human and 9 paired artificial bone samples
PublicationThis study was designed to compare compressive strength of cancellous bone retrieved from the femoral head in a specimen with and without guide wire hole, with comparison to synthetic bone samples. Femoral heads retrieved from 33 patients who sustained femoral neck fractures and underwent hip arthroplasty were cut into cuboids leaving two matching samples from the same femoral head. Similar samples were prepared from synthetic femurs....
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Debonding of coin-shaped osseointegrated implants: Coupling of experimental and numerical approaches
PublicationWhile cementless implants are now widely used clinically, implant debonding still occur and is difficult to anticipate. Assessing the biomechanical strength of the bone–implant interface can help improving the understanding of osseointegration phenomena and thus preventing surgical failures. A dedicated and standardized implant model was considered. The samples were tested using a mode III cleavage device to assess the mechanical...
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KNOWING WHEN TO SAY NO / SAPERE QUANDO DIRE NO
PublicationEver since we began illuminating the exterior of the slender skyscrapers built during the of 20s and 30s in XX century, urban lighting has been considered a way to beautify cities, and make them more visually prominent and safe. At that time, we knew so little about the impact of lighting on humans, flora and fauna, so it never occurred to lighting designers then, that their actions would have harmful consequences. In those days,...
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Biocompatibility and bioactivity of load-bearing metallic implants
PublicationThe main objective of here presented research is to develop the titanium (Ti) alloy base composite materials possessing better biocompatibility, longer lifetime and bioactivity behaviour for load-bearing implants, e.g. hip joint and knee joint endoprosthesis. The development of such materials is performed through: modeling the material behaviour in biological environment in long time and developing of new procedures for such evaluation;...
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Neohypoplasticity Revisited
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Modelling hydraulic and capillary-driven two-phase fluid flow in unsaturated concretes at the meso-scale with a unique coupled DEM-CFD technique
PublicationThe goal of the research was to demonstrate the impact of thin porous interfacial transition zones (ITZs) between aggregates and cement matrix on fluid flow in unsaturated concrete caused by hydraulic/capillary pressure. To demonstrate this impact, a novel coupled approach to simulate the two-phase (water and moist air) flow of hydraulically and capillary-driven fluid in unsaturated concrete was developed. By merging the discrete...
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Effect of gas content in macropores on hydraulic fracturing in rocks using a fully coupled DEM/CFD approach
PublicationW pracy skupiono się na wpływie zawartości gazu w makroporach skał na proces szczelinowania hydraulicznego. Proces został zasymulowany przez połączenie metody elementów dyskretnych (DEM) z obliczeniową dynamiką płynów (CFD) w ramach dwuwymiarowych (2D) warunków izotermicznych. Mechaniczne zachowanie skały zostało zasymulowane za pomocą DEM, a CFD została wykorzystana do opisu zachowanie przepływu laminarnego, dwufazowego płynu...
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Comparison of continuous and discontinuous constitutive models to simulate concrete behaviour under mixed mode failure conditions
PublicationW artykule porównano modele MES ciągłe i nieciągłe do symulacji zachowania betonu w warunkach mieszanego zniszczenia. W ramach modeli ciągłych zastosowano modele sprężysto-plastyczne oraz modele z redukcją sztywności sprężystej i nielokalnym osłabieniem. W ramach modeli nieciągłych zastosowano XFEM. Przedmiotem obliczeń były strefy lokalizacji i rysy w warunkach mieszanego zniszczenia wg testu doświadczalnego Nooru-Mohameda.
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Non-coaxiality and stress-dilatancy rule in granular materials: FE-investigation within micro-polar hypoplasticity
PublicationW artykule przedstawiono wyniki numerycznej analizy nieosiowości i zasady naprężenie-dylatancja w materiałach granulowanych podczas ściskania dwuosiowego. Obliczenia wykonano przy zastosowaniu metody elementów skończonych i mikropolarnego modelu hipoplastycznego.
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Modeling of bearing capacity of footings on sand within stochastic micro-polar hypoplasticity.
PublicationAnalizowano numerycznie efekt wstępnego rozkładu wskaźnika porowatości na wytrzymałość i strefy ścinania w problemach fundamentów na piasku w skali modelowej. Obliczenia wykonano przy zastosowaniu stochastycznej metody elementów skończonych i mikropolarnego modelu hipoplastycznego. Wskaźnik porowatości miał formę skorelowanych pól stochastycznych. Dodatkowo obliczono efekt skali dla 3 różnych szerokości fundamentów.
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Deterministic and statistical size effect during shearing of granular layer within a micro-polar hypoplasticity
PublicationArtykuł omawia deterministyczny i statystyczny efekt skali w materiałach granulowanych podczas ścinania cienkiej warstwy piasku między dwoma bardzo szorstkimi ścianami. Obliczenia wykonano metodą elementów skończonych na bazie mikropolarnego prawa hipoplastycznego. Przyjęto różne metody redukujące ilość realizacji pól losowych dla początkowego wskaźnika porowatości..
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Discrete modeling of micro-structure evolution during concrete fracture using DEM
PublicationW artykule pokazano wyniki dyskretne DEM dla betonu poddanego ściskaniu i rozciąganiu jednoosiowemu. Wyniki siła-przemieszczenie i zarysowania porównano z doświadczeniami. Szczególną uwagę zwrócono na zjawiska mikrostrukturalne podczas zarysowania na poziomie kruszywa.
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Discrete simulations of a triaxial compression test for sand by DEM.
PublicationArtykuł przedstawia wyniki symulacji dyskretnych dla ściskania trójosiowego stosując metodę elementów dyskretnych DEM. Symulacje wykonano dla piasku. Zastosowano kuli z momentami kontaktu do symulacji kształtu ziaren. Przeprowadzono analizy dla różnych zmiennych parametrów: średnica piasku, krzywa uziarnienia, kształt ziaren, wymiary próbki i warunki brzegowe.
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The role of organic and mineral constituents on kerogen transformation ratio
PublicationThe main aim of this dissertation is to determine the role of mineral and organic matter constituents in kerogen transformation ratio. Practical aspects of the work include application of the results in the assessment of hydrocarbon production potential; to make process of hydrocarbon recovery more predictable consistent and efficient. The work used shale from the Vaca Muerta formation from the Nequen basin in Argentina. The formation...
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Heritability and other determinants of left ventricular diastolic function in the family-based population study
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Doppler indexes of left ventricular systolic and diastolic function in relation to the arterial stiffness in a general population
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Impact and pitfalls of scaling of left ventricular and atrial structure in population-based studies
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Global wealth disparities drive adherence to COVID-safe pathways in head and neck cancer surgery
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Outcomes of gynecologic cancer surgery during the COVID-19 pandemic: an international, multicenter, prospective CovidSurg-Gynecologic Oncology Cancer study
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Effect of COVID-19 pandemic lockdowns on planned cancer surgery for 15 tumour types in 61 countries: an international, prospective, cohort study
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