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Search results for: CONCRETE FRACTURE FEM DEM X-RAY COMPUTED TOMOGRAPHY
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Intracranial hemorrhage detection in 3D computed tomography images using a bi-directional long short-term memory network-based modified genetic algorithm
PublicationIntroduction: Intracranial hemorrhage detection in 3D Computed Tomography (CT) brain images has gained more attention in the research community. The major issue to deal with the 3D CT brain images is scarce and hard to obtain the labelled data with better recognition results. Methods: To overcome the aforementioned problem, a new model has been implemented in this research manuscript. After acquiring the images from the Radiological...
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Visualizing the macroscale spatial distributions of biofilms in complex flow channels using industrial computed tomography
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Local structural and chemical ordering of nanosized Pt(3±δ)Co probed by multiple-scattering x-ray absorption spectroscopy
PublicationThis work reports a detailed investigation of the local structure and chemical disorder of a Pt(3±δ)Co thin film and Pt(3±δ)Co nanoparticles. We have used a combination of techniques including x-ray absorption spectroscopy (XAS), x-ray diffraction (XRD), and high-resolution transmission electron microscopy (TEM). The important effect of chemical ordering on pair and three-atom configurations has been studied using computer simulations...
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Response of thermoluminescence dosemeters statically exposed to X-ray radiation
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High-pressure X-ray Diffraction Study of SrSi2O2N2:Eu2+
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Confined lead nanogranules investigated by X-ray absorption spectroscopy
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Numerical mesoscopic analysis of fracture in fine-grained concrete
PublicationArtykuł omawia wyniki analizy mezoskopowej procesu pękania w betonie podczas zginania. Obliczenia wykonano na poziomie mezo wykorzystując model degradacji sztywności z nielokalnym osłabieniem. Zbadano wpływ właściwości kruszywa, stref przejściowych, nacięcia oraz długości charakterystycznej mikrostruktury na zachowanie sie betonu.
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Short-range order structure and free volume distribution in liquid bismuth: X-ray diffraction and computer simulations studies
PublicationThe structure of liquid bismuth was studied by X-ray diffraction and computer simulation methods. The contraction of the atomic structure within the first coordination sphere in the temperature interval of 575- 1225 K is reported. The temperature dependencies of the coordination numbers and of the free volume are analysed. On the basis of the temperature dependencies of the free volume, the temperature dependencies of viscosity...
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Computer-Aided Diagnosis of COVID-19 from Chest X-ray Images Using Hybrid-Features and Random Forest Classifier
PublicationIn recent years, a lot of attention has been paid to using radiology imaging to automatically find COVID-19. (1) Background: There are now a number of computer-aided diagnostic schemes that help radiologists and doctors perform diagnostic COVID-19 tests quickly, accurately, and consistently. (2) Methods: Using chest X-ray images, this study proposed a cutting-edge scheme for the automatic recognition of COVID-19 and pneumonia....
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Evolution of the nanostructure of Pt and Pt–Co polymer electrolyte membrane fuel cell electrocatalysts at successive degradation stages probed by X-ray photoemission
PublicationWe present a set of XPS (X-ray photoemission spectroscopy) measurements and detailed data-analysis of electrodes for polymer electrolyte membrane fuel cell (PEMFC) based on carbon supported catalysts (Pt and Pt–Co) subjected to a step-like potential cycling (accelerated degradation test). The results of the measurements complete and corroborate parallel TEM (transmission electron microscopy), XRD (X-ray diffraction) and XAS (X-ray...
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Perfusion computed tomography: 4 cmversus8 cm coverage size in subjects with chronic carotid artery stenosis
PublicationOBJECTIVE: The impact of coverage size on global cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT) and time to peak (TTP) parameters has not been investigated in patients with chronic carotid artery stenosis. METHODS: 63 patients with stenosis of >70% within a single internal carotid artery and neurological symptoms were randomly assigned to two well-matched groups. Differences in CT perfusion scan...
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Comparative X-ray diffraction and Mössbauer spectroscopy studies of BiFeO3 ceramics prepared by conventional solid-state reaction and mechanical activation
PublicationThe aim of this work was to prepare BiFeO3 by modified solid-state sintering and mechanical activation processes and to investigate the structure and hyperfine interactions of the material. X-ray diffraction and Mössbauer spectroscopy were applied as complementary methods. In the case of sintering, BiFeO3 phase was obtained from the mixture of precursors with 3 and 5 % excess of Bi2O3 during heating at 1023 K. Small amounts of...
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Performance of a fuel cell optimized for in situ X-ray absorption experiments
PublicationKomercyjna komórka ogniwa paliwowego typu PEM została zmodyfikowana w celu realizacji pomiaru XAS w warunkach pracy ogniwa. Modyfikacja komórki miała na celu optymalizację jej parametrów pod kątem eksperymentu XAS realizowanego w modzie transmisyjnym i fluorescencyjnym, poprzez minimalizację absorpcji komórki, przy zachowaniu jej parametrów elektrochemicznych. W pracy zostały zaprezentowane szczegóły techniczne komórki a jej efektywność...
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K X-ray line energies as diagnostics of warm dense plasma
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Relativistic calculations of X-ray photoelectron spectra and the accuracy of the IOTC method*
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The K X-ray line structures for a warm dense copper plasma
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European X-Ray Free Electron Laser (EXFEL): local implications
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Proton transfer and hydrogen bonds in supramolecular, self-assembled structures of imidazolium silanethiolates. X-ray, spectroscopic and theoretical studies
PublicationThe reaction of 1-methylimidazole, 2-ethyl-4-methylimidazole and 2-ethylimidazole with tris(2,6- diisopropylphenoxy)silanethiol (TDST) leads to the formation of three new salts, which have been characterized by elemental analyses, thermogravimetric analyses, FTIR spectroscopy, and their structures were determined by single-crystal X-ray diffraction. Structural analyses indicate that in all three compounds a proton transfer has...
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Simulations of fracture in concrete elements using continuous and discontinuous models
PublicationArtykuł przedstawia wyniki symulacji MES w elementach betonowych przy zastosowaniu modeli ciągłych i nieciągłych. Stosując modele ciągłe symulowano proces lokalizacji odkształceń. Stosując modele nieciągłe symulowano proces zarysowania. Obliczenia wykonano dla różnych typów obciążeń.
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Modelling of fracture process in concrete using a novel lattice model.
PublicationArtykuł omawia wyniki modelowania procesu zarysowania w elementach betonowych przy zastosowaniu dyskretnego modelu kratownicowego. Beton był modelowany na poziomie mezoskali z uwzględnieniem 3 faz: kruszywa, zaczynu cementowego i stref kontaktu. Obliczenia wykonano dla rozciągania i ścinania połączonego z rozciąganiem.
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A 3D lattice model to describe fracture process in fibrous concrete
PublicationArtykuł omawia wyniki modelowania procesu zarysowania w elementach betonowych zawierające stalowe włókna przy zastosowaniu dyskretnego modelu kratownicowego. Beton był modelowany na poziomie mezoskali z uwzględnieniem 5 faz: kruszywa, zaczynu cementowego, włókien i obu stref kontaktu. Obliczenia trójwymiarowe wykonano dla jednoosiowego rozciągania.
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Study of fracture process in concrete using a discrete lattice model.
PublicationW artykule omówiono wyniki numeryczne z zastosowaniem dyskretnego modelu rusztowego złożonego z belek do symulacji procesu zarysowania w elementach betonowych. Obliczenia wykonano dla różnych procesów obciążeniowych. Wyniki porównano jakościowo z wynikami doświadczeń.
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Application of vibrational spectroscopy, thermal analyses and X-Ray diffraction in the rapid evaluation of the stability in solid-state of ranitidine, famotidine and cimetidine
PublicationThis paper reports the study on applicability of Fourier transform infrared (FTIR), near-infrared (NIR) and Raman spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) for the estimation of the chemical stability and photostability of histamine H2-receptor antagonist substances. Ranitidine hydrochloride (RAN), famotidine (FAM) and cimetidine (CIM) were tested and differences in sensitivity were measured...
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Modeling of capillary fluid flow in concrete using a DEM-CFD approach
PublicationSformułowano połączone podejście do modelowania dwufazowego przepływu wody napędzanego hydraulicznie i kapilarnie w nienasyconym betonie. Proces przepływu analizowano numerycznie w mezoskali w warunkach dwuwymiarowych (2D), łącząc metodę elementów dyskretnych (DEM) z obliczeniową dynamiką płynów (CFD) w warunkach izotermicznych. Przeprowadzono w pełni sprzężone hydromechaniczne testy symulacyjne na małych próbkach betonu o uproszczonej...
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Inner-shell fragmentation of molecules into neutral fragments in high-Rydberg states induced by soft X-ray excitation with pulsed-field ionization
PublicationIn the present communication, we will show the results of measurements probing the production of neutral high-Rydberg fragments at the K edges of the molecules containing oxygen and nitrogen atoms. The experiments were performed at the Gas Phase beamline of the Elettra synchrotron radiation laboratory (Trieste, Italy), exploiting a combined soft X-ray excitation with pulsed-field ionization and ion time-of-flight (TOF) spectrometry...
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Study of microstress state of P91 steel using complementary mechanical Barkhausen, magnetoacoustic emission, and X-ray diffraction techniques
PublicationThe paper deals with assessment of microstress state of martensite P91 steel using three complementary techniques: mechanical Barkhausen emission, magnetoacoustic emission (MAE), and X-ray diffraction (XRD) profile analysis. Magnetic coercivity Hc and microstructure were investigated with inductive magnetometry and magnetic force microscopy (MFM), respectively. Internal stress level of P91 steel was modified by heat treatment....
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A coupled constitutive model for fracture in plain concrete based on continuum theory with non-local softening and eXtended Finite Element Method
PublicationThe paper presents a constitutive model for concrete which combines a continuous and discontinuous fracture description. In a continuum regime, two different constitutive laws were used. First, a plasticity model with a Rankine failure criterion and an associated fl ow rule was used. Second, a constitutive law based on isotropic damage mechanics was formulated. In order to capture the width of a localized zone and to obtain mesh-independent...
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FEM and experimental investigations of concrete temperature field in the massive stemwall of the bridge abutment
PublicationThe paper deals with the prediction of early-age concrete temperature of cast-in-place stemwall of the bridge abutment. The considered object is an arch bridge located in Gda´nsk. In the case of massive structures, it is particularly important to not exceed the temperature difference between the core and the concrete surface. Too high temperature gradient generates an increase in thermal stresses, what could be the reason of exceeding...
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Soft X-ray Induced Production of Neutral Fragments in High-Rydberg States at the O 1s Ionization Threshold of the Water Molecule
PublicationDissociation of water molecules after soft X-ray absorption can yield neutral fragments in high-Rydberg (HR) states. We have studied the production of such fragments by field ionization and ion time-of-flight (TOF) spectrometry. Neutral HR fragments are created at all resonances below the O 1s ionization potential (IP) and particularly within 1 eV above the O 1s IP. The latter effect is due to the recapture of the O 1s photoelectrons...
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X-ray and NMR structural studies of the series of porphyrazines with peripheral pyrrolyl groups
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Structure of Kα1,2 - and Kβ1,3 -emission x-ray spectra for Se, Y, and Zr
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Precise x-ray energies of gadolinium determined by a combined experimental and theoretical approach
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Two-photon double ionization of atoms in attosecond x-ray radiation fields
PublicationWe consider two-photon double ionization of helium with 100, 200, and 400 eV excess energy for the two ejected electrons, corresponding to photon energies of 89.5, 139.5, and 239.5 eV, respectively. We focus on the case of ultrashort pulses (two oscillations of the field) and develop an approach to calculate the two-photon transition matrix elements within the lowest order of the time-dependent perturbation theory. One of the...
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BIOLOGICAL AGE ASSESSMENT ALGORITHMS BASED ON X-RAY IMAGES OF BONE TISSUE
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Testing interaction models by using x-ray absorption spectroscopy: solid Pb
PublicationPraca prezentuje zastosowanie metody EXAFS jako narzędzia do testowania potencjałów oddziaływań międzyatomowych używanych w symulacjach dynamiczno-molekularnych na przykładzie czystego ołowiu w fazie stałej (od temperatury pokojowej do temperatury topnienia). Testowaniu poddano następujące potencjały: dwuciałowy empiryczny potencjał Dzugutova, Larssona i Ebbsjo (DLE), potencjał ciasnego wiązania (TB) i potencjał w modelu osadzonego...
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Investigations of size effect in tensile fracture of concrete using a lattice model
PublicationArtykuł przedstawia symulacje efektu skali w betonie podczas rozciągania przy zastosowaniu nowego modelu siatkowego. Zbadano wpływ rozkładu i wielkości kruszywa oraz wpływ strefy kontaktu na efekt skali.
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Effect of exercise training on insulin sensitivity, mitochondria and computed tomography muscle attenuation in overweight women with and without polycystic ovary syndrome
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Mitigation effect of face shield to reduce SARS-CoV-2 airborne transmission risk: Preliminary simulations based on computed tomography
PublicationWe aimed to develop a model to quantitatively assess the potential effectiveness of face shield (visor) in reducing airborne transmission risk of the novel coronavirus SARS-CoV-2 during the current COVID-19 pandemic using the computational fluid dynamics (CFD) method. The studies with and without face shield in both an infected and healthy person have been considered in indoor environment simulation. In addition to the influence...
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Mitigation effect of face shield to reduce SARS-CoV-2 airborne transmission risk: Preliminary simulations based on computed tomography
PublicationWe aimed to develop a model to quantitatively assess the potential effectiveness of face shield (visor) in reducing airborne transmission risk of the novel coronavirus SARS-CoV-2 during the current COVID-19 pandemic using the computational fluid dynamics (CFD) method. The studies with and without face shield in both an infected and healthy person have been considered in indoor environment simulation. In addition to the influence...
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Enhancing Luminescence and X-ray Absorption Capacity of Eu3+:LaF3 Nanoparticles by Bi3+ Codoping
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The K x-ray line structures of the 3d-transition metals in warm dense plasma
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On the interpretation of high-resolution x-ray spectra from JET with an ITER-like wall
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The bismuth atom neighbourhood in bismuth-silicate glasses from X-ray absorption experiment
PublicationPraca zawiera wyniki strukturalnej analizy EXAFS lokalnego otoczenia atomów bizmutu w krystalicznym tlenku bizmutu (odmiana alfa) i w szklach bizmutowo-krzemianowych o składzie xBi2O3 (1-x)SiO2,x=0.3, 0.4, 0.5, 0.6. Analizę XA- FS realizowano w oparciu o metodę GNXAS. Otrzymane wyniki porównano z danymi literaturowym.
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Experimental investigations on water sorptivity in mortars with the use of X-ray micro-CT system.
PublicationW pracy doswiadczalnej zbadano zjawisko sorpcji wody w pryzmatycznych próbkach zapraw, które jest ściśle powiązane z trwałością materiału. Sorpcyjność oceniana na etapie ustalonym w połączeniu z warunkami zewnętrznymi może być wykorzystana do przewidywania okresu użytkowania. Sorpcyjność początkową i wtórną wody w próbkach zapraw nienasyconych zmierzono w badaniach laboratoryjnych zgodnie z normą amerykańską ASTM C 1585–04. Wpływ...
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Enhancement of the Magnetic Coupling in Exfoliated CrCl 3 Crystals Observed by Low‐Temperature Magnetic Force Microscopy and X‐ray Magnetic Circular Dichroism
PublicationMagnetic crystals formed by 2D layers interacting by weak van der Waals forces are currently a hot research topic. When these crystals are thinned to nanometric size, they can manifest strikingly different magnetic behavior compared to the bulk form. This can be the result of, for example, quantum electronic confinement effects, the presence of defects, or pinning of the crystallographic structure in metastable phases induced by...
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Effect of aggregate structure on fracture process in concrete using 2D lattice model
PublicationArtykuł przedstawia symulacje rys w betonie przy zastosowaniu nowego modelu siatkowego. Zbadano wpływ rozkładu i wielkości kruszywa oraz wpływ strefy kontaktu na nośność i propagacje rys. Obliczenia były dwuwymiarowe.
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Measurements and calculations of the width of the fracture process zones on the surface of notched concrete beams
PublicationArtykuł omawia wyniki pomiaru i analizy numerycznej szerokości strefy pękania w belkach betonowych z nacięciem. Do pomiarów zastosowano metodę DIC. Do symulacji zastosowano model sprężysto - plastyczny i model z degradacją sztywności. Oba modele zostały rozszerzone o nielokalne osłabienie. Wyniki symulacji porównano z doświadczeniami.
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Performance evaluation of an improved optical computed tomography polymer gel dosimeter system for 3D dose verification of static and dynamic phantom deliveries
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The X-ray photoelectron spectroscopy of surface composition of aged mixed copper manganese oxide catalysts
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Modeling of the L and M x-ray line structures for tungsten in high-temperature tokamak plasmas
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