Search results for "25"
showing 10 items of 3263 documents
FRCM systems for strengthening masonry structures
2017
Composite materials have been widely used for strengthening weak masonry buildings. Particularly, wrapping with fibre reinforced polymer (FRP) composites has become a common method for strengthening masonry members primarily subjected to compressive static loads or seismic actions. More recently, in an effort to alleviate some drawbacks associated with the use of FRP materials, fibrereinforced cementitious matrix (FRCM) composites have received a lot of interests for external strengthening of historical masonry structures. It is used as an alternative to FRP in situations where these composites have shown some disadvantages or their use is banned. This paper presents a literature review on …
Two-dimensional Banach spaces with polynomial numerical index zero
2009
We study two-dimensional Banach spaces with polynomial numerical indices equal to zero.
Mehāniskās aktivācijas ietekme uz nātrija bismuta titanāta keramikas izgatavošanu.
2022
“Mehāniskās aktivācijas ietekme uz nātrija bismuta titanāta keramikas izgatavošanu” Atvars A., zinātniskie darba vadītāji vadošā pētniece Dr. phys. Dunce M. un asoc. prof. Dr. chem. Vaivars G. Bakalaura darbs. (46 lapas, 27 attēli, 49 literatūras avoti, 3 pielikumi). Latviešu valodā Bakalaura darba ietvaros tika veikta nātrija bismuta titanāta (Na0,5Bi0,5TiO3) un cietā šķīduma 0,975(0,94Na0,5Bi0,5TiO3-0,06BaTiO3)-0,025LiNbO3 iegūšana, izmantojot cietfāžu reakcijas metodi, veicot mehānisko aktivāciju vienā no posmiem. Nepieciešamie savienojumi tika iegūti, izmantojot nātrija karbonātu (Na¬2CO3), bismuta (III) oksīdu (Bi2O3), titāna dioksīdu (TiO2), litija karbonātu (Li2CO3), niobija (V) oksī…
Diving below the spin-down limit: Constraints on gravitational waves from the energetic young pulsar PSR J0537-6910
2021
We present a search for continuous gravitational-wave signals from the young, energetic X-ray pulsar PSR J0537-6910 using data from the second and third observing runs of LIGO and Virgo. The search is enabled by a contemporaneous timing ephemeris obtained using NICER data. The NICER ephemeris has also been extended through 2020 October and includes three new glitches. PSR J0537-6910 has the largest spin-down luminosity of any pulsar and is highly active with regards to glitches. Analyses of its long-term and inter-glitch braking indices provided intriguing evidence that its spin-down energy budget may include gravitational-wave emission from a time-varying mass quadrupole moment. Its 62 Hz …
Stochastic Galerkin method for cloud simulation
2018
AbstractWe develop a stochastic Galerkin method for a coupled Navier-Stokes-cloud system that models dynamics of warm clouds. Our goal is to explicitly describe the evolution of uncertainties that arise due to unknown input data, such as model parameters and initial or boundary conditions. The developed stochastic Galerkin method combines the space-time approximation obtained by a suitable finite volume method with a spectral-type approximation based on the generalized polynomial chaos expansion in the stochastic space. The resulting numerical scheme yields a second-order accurate approximation in both space and time and exponential convergence in the stochastic space. Our numerical results…
Pre- and syn-eruptive geochemistry of volcanic gases from Soufriere Hills of Montserrat, West Indies
1998
International audience; Soufriere Hills fumaroles contained magmaderived volatiles before and during the eruption initiated in 1995 but also preserved a typical and quite steady hydrothermal coinposition. Chemical changes due to increased boiling and a greater input of oxidizing magmatic gas occurred only at Galway's Soufriere, the most active fumarolic field. Hydrothermal buffering of the fumaroles has been favoured by their remote location (!-2 km) froin the eruptive vents and by a preferential degassing of the uprising magma through intrusive conduits under the crater. High temperature (720øC) gas collected froin the extruding lava dome in Feb. 1996 was chemically and isotopically repres…
Dental wear at macro- and microscopic scale in rabbits fed diets of different abrasiveness: A pilot investigation
2020
To differentiate the effects of internal and external abrasives on tooth wear, we performed a controlled feeding experiment in rabbits fed diets of varying phytolith content as an internal abrasive and with addition of sand as an external abrasive. 13 rabbits were each fed one of the following four pelleted diets with different abrasive characteristics (no phytoliths: lucerne L; phytoliths: grass G; more phytoliths: grass and rice hulls GR; phytoliths plus external abrasives: grass, rice hulls and sand GRS) for two weeks. At the end the feeding period, three tooth wear proxies were applied to quantify wear on the cheek teeth at macroscopic and microscopic wear scales: CT scans were obtained…
Ammonoids and quantitative biochronology - A unitary association perspective
2015
Ammonoid evolutionary changes have long been recognized to be excellent time markers. They are the major macrofossil group to date and correlate Paleozoic and Mesozoic marine strata. Originations and extinctions of ammonoid species are commonly used to define GSSPs and build high resolution biozonations. Biochronology is now an advanced field with the recent development of computerized, quantitative methods yielding robust biochronological schemes. It has been demonstrated that such quantitative biochronological methods are very efficient to resolve (often complex) biostratigraphic contradictions and produce accurate and high resolution biozonations, thus enabling precise dating and correla…
Marine Early Triassic Actinopterygii from Elko County (Nevada, USA): implications for the Smithian equatorial vertebrate eclipse
2017
AbstractThe Early Triassic vertebrate record from low paleolatitudes is spotty, which led to the notion of an ‘equatorial vertebrate eclipse’ during the Smithian. Here we present articulated ray-finned fishes (Actinopterygii), collected from the marine Lower Triassic Thaynes Group at three new localities in Elko County (Nevada, USA), which were deposited within the equatorial zone. From the Smithian of the Winecup Ranch, we describe two partial skulls of the predatory actinopterygianBirgeria(Birgeriidae), attributed toB.americananew species andBirgeriasp.Birgeria americanan. sp. is distinguished from other species by a less reduced operculogular series. With an estimated total length of 1.7…
Transient metazoan reefs in the aftermath of the end-Permian mass extinction
2011
5 pages; International audience; Recovery from the devastating Permian-Triassic mass extinction about 252 million years ago is usually assumed to have spanned the entire 5 million years of the Early Triassic epoch1,2. The post-crisis interval was characterized by large-scale fluctuations of the global carbon cycle and harsh marine conditions, including a combination of ocean acidification, euxinia, and fluctuating productivity3. During this interval, metazoan-dominated reefs are thought to have been replaced by microbial deposits that are considered the hallmark of the Early Triassic4-7. Here we use field and microscopic investigations to document Early Triassic bioaccumulations and reefs f…