Search results for "MECHANICS"
showing 10 items of 9361 documents
Speed-Related Energy Flow and Joint Function Change During Human Walking.
2021
During human walking, mechanical energy transfers between segments via joints. Joint mechanics of the human body are coordinated with each other to adapt to speed change. The aim of this study is to analyze the functional behaviors of major joints during walking, and how joints and segments alter walking speed during different periods (collision, rebound, preload, and push-off) of stance phase. In this study, gait experiment was performed with three different self-selected speeds. Mechanical works of joints and segments were determined with collected data. Joint function indices were calculated based on net joint work. The results show that the primary functional behaviors of joints would n…
Kinematics of the patellofemoral joint. Investigations on a computer model with reference to patellar fractures.
1990
Patellofemoral kinematics were studied on a computer model. The articulating point of the patella moves from distal to proximal during flexion, until the quadriceps tendon starts to turn around the femur tendo-femoral gliding. The pattern of patellofemoral movement consists of a gliding and rolling component, the latter at its maximum at the beginning of flexion. The pathway of the instant centers of motion moves from dorsal to ventral during flexion. Stress analysis shows that the contact area is at all times the area of maximum bending stress. The distal part of the patella is the part with mechanical stress at all angles of flexion. The conclusions to be drawn for treatment are that frac…
Patient-specific computational evaluation of stiffness distribution in ascending thoracic aortic aneurysm
2021
Quantifying local aortic stiffness properties in vivo is acknowledged as essential to assess the severity of an ascending thoracic aortic aneurysm (ATAA). Recently, the LESI (local extensional stiffness identification) methodology has been established to quantify non-invasively local stiffness properties of ATAAs using electrocardiographic-gated computed tomography (ECG-gated CT) scans. The aim of the current study was to determine the most sensitive markers of local ATAA stiffness estimation with the hypothesis that direct measures of local ATAA stiffness could better detect the high-risk patients. A cohort of 30 patients (12 BAV and 18 TAV) referred for aortic size evaluation by ECG-gated…
In Vitro Study on Bone Heating during Drilling of the Implant Site: Material, Design and Wear of the Surgical Drill
2020
Objective: An in vitro study was made to compare mean thermal variation according to the material, design and wear of the surgical drills used during dental implant site preparation. Material and methods: Three study groups (stainless steel drills with straight blades
HHT-alpha and predictor-corrector scheme for dynamic contact problem by Nitsche's method
2022
Dans ce travail nous sommes intéressés par le problème de contact unilatéral en dynamique et sans frottement. Nous nous concentrons sur l'évolution en temps de l'impact d'un corps élastique linéaire sur un obstacle rigide, et avons souhaité en particulier étudier comment combiner des schémas en temps comme HHT et prédicteur-correcteur avec un traitement du contact via Nitsche, ce qui n'a jamais été effectué auparavant. Nous présenterons aussi quelques résultats numériques en faisant attention au comportement numérique : stabilité du schéma, conservation ou non de l'énergie et oscillations parasites. Mots clés-problème de contact, méthode de Nitsche, éléments finis, dynamique.
Tetragonal tungsten bronzes Nb8−xW9+xO47−δ: optimization strategies and transport properties of a new n-type thermoelectric oxide
2015
Engineering of nanoscaled structures may help controlling the electrical and thermal transport in solids, in particular for thermoelectric applications that require the combination of low thermal conductivity and low electrical resistivity. The tetragonal tungsten bronzes Nb8−xW9+xO47 (TTB) allow a continuous variation of the charge carrier concentration while fulfilling at the same time the concept of a “phonon-glass electron-crystal” through a layered nanostructure defined by intrinsic crystallographic shear planes. The thermoelectric properties of the tetragonal tungsten bronzes Nb8−xW9+xO47−δ (0 < x < 2) were studied in the temperature range from 373 to 973 K. Structural defects and the…
Narracja historyczna w mechanice gry wideo na przykładzie cywilizacji bizantyjskiej w Age of Empires II
2018
Narracja w grach może występować w wielu formach i być zawarta w bardzo różnych ich elementach. Warto tu przede wszystkim wyróżnić ludonarrację – zawartą w mechanizmach samej rozgrywki, jak i narrację ramową, która występuje w oderwaniu od elementów interaktywnych i immersyjnych. Od dawna zarówno twórcy, jak i badacze gier rozważają kwestię wykorzystania ich narracji do poszerzania i popularyzacji wiedzy historycznej. Autorzy gry Age of Empires II pozornie nie mieli jednak podobnych ambicji – w grze możemy wszak zestawić ze sobą w otwartym konflikcie tak odległe cywilizacje jak Aztekowie i Hunowie. Gdy jednak przyjrzymy się dziełu Ensemble Studios, zauważymy, że narracja historyczna pojawia…
Coherence in neutrino oscillations
2011
The theory of neutrino oscillations has turned out to be the most reasonable explanation to the observed violations in lepton number conservation of solar and atmospheric neutrino fluxes. A derivation of the most important results of this theory is first given using a plane wave treatment and subsequently using a three-dimensional shape-independent wave packet approach. Both methods give the same oscillation patterns, but only the latter one serves as a decent starting point for analyzing coherence in neutrino oscillations. A numerical analysis of the oscillation patterns on various distance scales is also given to graphically illustrate the phenomenon of neutrino oscillation and loss of co…
Noise effect in a sine-Gordon Lattice
2013
International audience; This paper is devoted to the influence of internal noise in a sine-Gordon chain exhibiting the well known nonlinear supratransmission phenomenon. It is shown that spatiotemporal noise can trigger breather modes with a given probability in a range of parameters where they do not occur without noise. A frequency analysis is carried out to quantify the degree of coherence of the emitted breather. It is shown that there exists an appropriate amount of noise which ensures the existence of breather modes with the best coherence.
Nonlinear dissipation phenomena in optomechanics
2016
Yksikään kvanttisysteemi ei voi olla täysin eristetty ympäristöstään, mikä johtaa informaation välittymiseen systeemin ja ympäristön välillä. Optomekaniikassa, missä tyypillinen tutkittava systeemi on peileistä koostuva optinen kaviteetti yhdistettynä mekaaniseen värähtelijään, systeemin ja ympäristön lineaarisesta kytkennästä johtuvat dissipaatioilmiöt ovat hyvin tunnettuja. Epälineaarisia ilmiöitä ei kuitenkaan ymmärretä yhtä laajasti. Tutkin epälineaarista kytkentää kaviteetin ja lämpökylvyn välillä ja havainnollistan tästä kytkennästä johtuvia ilmiöitä kuten epälineaarista dissipaatiota. Esitän myös optisen kaviteetin epälineaarisen dissipaation oikeuttavan mallin, missä optinen kavitee…