Search results for "Ferro"
showing 10 items of 2451 documents
On the theory of domain structure in ferromagnetic phase of diluted magnetic semiconductors
2006
Abstract We present a comprehensive analysis of domain structure formation in ferromagnetic phase of diluted magnetic semiconductors (DMS) of p-type. Our analysis is carried out on the base of effective magnetic free energy of DMS calculated by us earlier [Yu.G. Semenov, V.A. Stephanovich, Phys. Rev. B 67 (2003) 195203]. This free energy, substituting DMS (a disordered magnet) by effective ordered substance, permits to apply the standard phenomenological approach to domain structure calculation. Using coupled system of Maxwell equations with those obtained by minimization of above free energy functional, we show the existence of critical ratio ν cr of concentration of charge carriers and ma…
Photoionization of Polarized Atoms Applications to Free Atoms and Ferromagnets
1996
Discussion of connections between different phenomena observed in seemingly different situations usually helps to better understanding of the physics of underlying processes. Some time ago Farago1 discussed analogies and contrasts between light polarization and electron spin polarization. He showed that though in both cases the same Stokes vector formalism2 can be applied, the analogies between them have rather limited validity. We will discuss here the applicability of equations derived for the description of photoionization of free polarized atoms3,4 to photoemission from ferromagnets5,6. We show that qualitative features of photoemission from core levels of ferromagnets are correctly rep…
Thermophoretic separation of a ferrofluid–water emulsion: preliminary experiments
2002
Abstract The Soret effect in an emulsion (microdroplets of hydrocarbon based ferrofluid in water) is evaluated from the separation measurements in vertical thermodiffusion column. The particle concentration in column ends is detected from the resonance frequency of LC oscillators with inductance coils mounted inside the column ends. The Soret coefficient S T of droplets is calculated from the initial part of dynamic separation curves. The measured value S T =−480 K −1 agrees qualitatively well with the calculated one found assuming the Maragoni-type transfer of liquid particles.
Drift of ferrocolloids through a cylindrical grid by magnetic force
2011
The subject of the paper is to investigate the coupling phenomena of magnetic and non-uniform temperature fields in ferrofluids. The coupling creates a special kind of mass transfer and an inhomogeneous concentration of ferrofluid arises especially near bodies, where higher field gradients are present. Particular attention is paid to the oriented mass transfer, i.e. the magnitude and direction of ferrofluid flux with respect to the temperature gradient and magnetic field. Quantitatively, oriented phoretic transport can be characterized by the magnetic Soret coefficient and osmotic pressure difference. The problem is solved using two-dimensional (2D) numerical simulations for the periodic st…
Mapováni spinů povrchových a bulkových Rashba stavů v tenkých vrstvách feroelektrického α-GeTe(111)
2015
Rozbíjení inverzní symetrie ve fereeleRashba efekt; Fotoemisse; DFTktrickém polovodiči způsobuje děleni stavů, tzv Rashba efekt. V tomto článku ukazujeme kompletně mapování spinové polarizace těchto Rashba stavů za pomoci spinovo rozlišené fotoemisse. The breaking of bulk inversion symmetry in ferroelectric semiconductors causes a Rashba-type spin splitting of electronic bulk bands. This is shown by a comprehensive mapping of the spin polarization of the electronic bands in ferroelectric α- GeTe(111) films using a time-of-flight momentum microscope equipped with an imaging spin filter that enables a simultaneous measurement of more than 10 000 data points. The experiment reveals an opposite…
Ferroelectric Liquid Crystalline Elastomers
2002
Ferroelectric LC-elastomers represent an interesting class of material because they combine the ordering of liquid crystalline ferroelectric phases and the rubber elasticity of polymer networks. Switching of the electric polarization leads to deformation of the polymer network, equivalent to stretching a spring, and creates a stress in the network of polymer chains. The interaction of mesogens and the network can be varied by using different topologies of net points: Crosslinking is carried out either within the siloxane sublayers (leading to fast switching elastomers) or between the siloxane sublayers (resulting in an elastomer that favors the ferroelectric switching state in which the cro…
Director orientation in chevron surface-stabilized ferroelectric liquid crystal cells. Verification of orientational binding at the chevron interface…
1990
Abstract We present results of theoretical modelling and experimental study of director distributions and the associated optical properties of chevron surface stabilized ferroelectric liquid crystal (SSFLC) cells. Chevron cells are modelled as being two stacked FLC slabs, described by distinct orientation distributions of the director [ncirc]-polarization P([ncirc] – P) couple. In each slab the [ncirc] – P distribution is governed by bulk Frank elastic and electric field-induced torques and by surface torques at the FLC-solid interface and at the chevron interface, where the two distributions are coupled. The optical properties of such structures are calculated numerically and the results t…
Estimating pollutant emissions based on speed profiles at urban roundabouts: A pilot study
2019
The paper describes the pilot study conducted to assess the feasibility of the empirical approach utilizing vehicle trajectory data from a smartphone app and the Vehicle-Specific Power methodology to estimate pollutant emissions at urban roundabouts. The goal of this research phase is to acquire instantaneous speed data from a sample of six roundabouts located in the road network of the City of Palermo, Italy, and quantify emissions generated by the test vehicle through the examined roundabouts. For the case studies of roundabouts acceleration events in the circulating and exiting areas contributed to about 25% of the emissions for a given speed profile. More in general, the results from th…
A model for evaluating the environmental and functional benefits of “innovative” roundabouts
2015
This study looks at the singling out of a multi-parameter criterion for choosing conventional or innovative roundabout layouts, by taking functional, environmental and economic aspects into consideration. The performances of three conventional roundabouts (with different lane number at entries and through the ring), turbo-roundabouts and roundabouts with right-turn bypass lane on all the arms (flower roundabouts) have been compared in terms of vehicle delays and pollutant (carbon dioxide, nitrogen oxides, particle pollution (PM10 and PM2.5)) emissions. By means of closed-form capacity models and with the help of COPERT IV© software, several traffic simulations have been carried out, referre…
Can crumb rubber modifier effectively replace the use of polymer- modified bitumen in asphalt mixture?
2021
Laboratory scale mechanical performances on six plant produced mixtures; three semi-dense surface courses and three dense binder courses modified with engineered crumb rubber (ECR) using the dry process are presented. The two types of mixtures produced and investigated fulfilled for the most part, the requirements of the Swiss and/or US standards regarding volumetric properties, water sensitivity and rutting. In advanced testing where no requirements exist, the dense ECR mixtures performed similar to the reference polymer modified mixtures and slightly worse for semi-dense mixtures in high temperature tests, where the binder becomes viscous in the rubber-binder composite and its ability to …