Search results for "OEL"
showing 10 items of 5270 documents
Topological polarization, dual invariants, and surface flat band in crystalline insulators
2020
We describe a three-dimensional crystalline topological insulator (TI) phase of matter that exhibits spontaneous polarization. This polarization results from the presence of (approximately) flat bands on the surface of such TIs. These flat bands are a consequence of the bulk-boundary correspondence of polarized topological media, and contrary to related nodal line semimetal phases also containing surface flat bands, they span the entire surface Brillouin zone. We also present an example Hamiltonian exhibiting a Lifshitz transition from the nodal line phase to the TI phase with polarization. Utilizing elasticity tetrads, we show a complete classification of 3D crystalline TI phases and invar…
Time-dependent quantum transport in nanosystems : a nonequilibrium Green's function approach
2016
A time-dependent extension to the Landauer–Büttiker approach to study transient quantum transport in arbitrary junctions composed of leads and conducting devices is developed. The nonequilibrium Green’s function approach is employed for describing the charge and heat transport dynamics. The importance of the developed method is that it provides a closed formula for the time-dependent density matrix in both electronic and phononic systems. In the electronic case the nonequilibrium conditions are due to a switch-on of a bias voltage in the leads or a perturbation in the junction whereas in the phononic case the central region of interest is coupled to reservoirs of di erent temperatures. In b…
Study of thermoelectric magnetohydrodynamic convection on solute redistribution during laser additive manufacturing
2020
Abstract Melt pools formed in laser additive manufacturing (AM) are subject to large thermal gradients, resulting in the formation of thermoelectric currents due to the Seebeck effect. When in the presence of an external magnetic field, a Lorentz force is formed which drives fluid flow in the melt pool. This Thermoelectric Magnetohydrodynamics (TEMHD) phenomenon, can have a significant impact on the melt pool morphology and can alter the microstructural evolution of the solidification process. By coupling steady-state mesoscopic melt pool calculations to a microscopic solidification model, predictions of the resulting microstructure for multiple deposited layers have been obtained. The resu…
Vibrational properties of semiconductor nanowires and nanowire heterostructures: ensembles and single nanowires
2013
A novel approach to nonlinear variable-order fractional viscoelasticity.
2020
This paper addresses nonlinear viscoelastic behaviour of fractional systems with variable time-dependent fractional order. In this case, the main challenge is that the Boltzmann linear superposition principle, i.e. the theoretical basis on which linear viscoelastic fractional operators are formulated, does not apply in standard form because the fractional order is not constant with time. Moving from this consideration, the paper proposes a novel approach where the system response is derived by a consistent application of the Boltzmann principle to an equivalent system, built at every time instant based on the fractional order at that instant and the response at all the previous ones. The ap…
Effect of Fe-incorporation on Structural and Optoelectronic Properties of Spin Coated p/n Type ZnO Thin Films
2020
Tuotantoeläinten hyvinvoinnin rakentuminen lihanjalostajien vastuullisuusviestinnässä
2017
Tutkielman tavoitteena on selvittää, miten lihanjalostajat kuvaavat tuotantoeläinten hyvinvointia kuluttajille suunnattujen verkkosivujensa vastuullisuusviestinnässä. Aihe on tärkeä, koska lihanjalostajien kuvaukset vaikuttavat kuluttajien tietoon, uskomuksiin ja ostopäätöksiin. Tutkimusongelmaa lähestytään kahdella tutkimuskysymyksellä: 1. Millaisia eläinten hyvinvoinnin representaatioita lihanjalostajat rakentavat verkkosivujensa vastuullisuusviestinnässä? 2. Miten representaatioita rakennetaan kielellisesti? Teoreettis-analyyttisenä viitekehyksenä tutkimuksessa toimivat kriittinen diskurssintutkimus ja systeemis-funktionaalinen kieliteoria. Kriittinen diskurssintutkimus tutkii kielenkäyt…
Early Jurassic (Sinemurian) gastropods from the Lusitanian Basin (west of Portugal)
2020
The Sinemurian gastropod specimens herein studied come from two sources: from museum collections and from samplings in field. The study of the Sinemurian gastropod specimens housed in the collections of the Museu Geológico (Laboratório Nacional de Energia e Geologia), Museu Nacional de História Natural e da Ciência (University of Lisbon), Museu da Ciência (University of Coimbra) and of the Museu de História Natural e da Ciência (University of Porto), has allowed the systematic and taxonomical update of this material. These specimens come mostly from Sinemurian outcrops in S. Pedro de Moel area and Coimbra region, and were collected by Paul Choffat and collaborators in the geological field w…
Our art the reasoning for the acquisition and placing of the public sculptures of the Jyväskylä City Art Collection in 1977-2007
2009
Postikorttien keräily ja taidepostikortti
2011
Pro gradu -työssä tutkitaan postikorttien keräilyä ja sen metodeita sekä etsitään määritelmä taidepostikortin käsitteelle. Tutkimus on toteutettu kokoamalla aineisto postikorttikeräilijöille lähetetyistä kyselylomakkeista, kahdesta postikorttikeräilijän haastattelusta sekä aihetta koskevasta artikkelilähteestä. Tutkimustulokset on saatu analysoimalla aineistosta saadut tiedot etsimällä yleisimpiä piirteitä postikorttikeräilystä ja siinä käytetystä metodiikasta. Lähdekirjallisuutta on käytetty analyysin ja määritelmien tukena. Myös taidepostikortin käsitteelle on koottu määritelmä aineistosta saatujen tulosten ja lähdekirjallisuuden avulla. Lisäksi taidepostikortteihin liittyen on tutkittu y…