Search results for "Migration"
showing 10 items of 1709 documents
Influence of the external stretching on hydrogen electromigration in palladium
2002
Abstract Electromigration and diffusion of hydrogen in palladium depending on unit elongation were investigated. It was found that the obtained experimental results cannot be described by means of a single flux of hydrogen, which diffuses in a gradient of electric field. In order to effectively explain the obtained results, a theoretical model was elaborated. It assumed the existence of the following two fluxes of hydrogen in the stretched metal: • Ji—of migration, according to the interstitial mechanism, and • Ji-d—of migration, according to the interstitial-defective mechanism. Dependence of effective valences and diffusion coefficients for both mechanisms of transportation were determine…
How the formation of interfacial charge causes hysteresis in perovskite solar cells
2018
In this study, we discuss the underlying mechanism of the current-voltage hysteresis in a hybrid lead-halide perovskite solar cell. We have developed a method based on Kelvin probe force microscopy that enables mapping charge redistribution in an operating device upon a voltage- or light pulse with sub-millisecond resolution. We observed the formation of a localized interfacial charge at the anode interface, which screened most of the electric field in the cell. The formation of this charge happened within 10 ms after applying a forward voltage to the device. After switching off the forward voltage, however, these interfacial charges were stable for over 500 ms and created a reverse electri…
Recombination in Perovskite Solar Cells
2017
Trap-assisted recombination, despite being lower as compared with traditional inorganic solar cells, is still the dominant recombination mechanism in perovskite solar cells (PSCs) and limits their efficiency. We investigate the attributes of the primary trap assisted recombination channels (grain boundaries and interfaces) and their correlation to defect ions in PSCs. We achieve this by using a validated device model to fit the simulations to the experimental data of efficient vacuum-deposited p-i-n and n-i-p CH3NH3PbI3 solar cells, including the light intensity dependence of the open circuit voltage and fill factor. We find that, despite the presence of traps at interfaces and grain bounda…
Pre-determining the location of electromigrated gaps by nonlinear optical imaging
2014
In this paper we describe a nonlinear imaging method employed to spatially map the occurrence of constrictions occurring on an electrically-stressed gold nanowire. The approach consists at measuring the influence of a tightly focused ultrafast pulsed laser on the electronic transport in the nanowire. We found that structural defects distributed along the nanowire are efficient nonlinear optical sources of radiation and that the differential conductance is significantly decreased when the laser is incident on such electrically-induced morphological changes. This imaging technique is applied to pre-determined the location of the electrical failure before it occurs.
Influence of external stretching on hydrogen electromigration in Pd and PdCu, PdAg alloys
2005
Influence of external stretching of Pd and Pd77Cu23 and Pd77Ag23 alloys on hydrogen electromigration in these systems was investigated. The electro-resistivity method was applied in the investigations. It was found that in order to furnish a full description of the kinetics and dynamics transport of hydrogen in the externally applied electric field to samples in the state of elastic and plastic stretching, it is not sufficient to provide a functional dependence of two commonly used parameters (diffusion coefficient D and effective valence Zeff) on degree of deformation. To describe the electromigration in these conditions a mathematical model was applied, which assumes the existence of two …
An Island Strategy for Memetic Discrete Tomography Reconstruction
2014
In this paper we present a parallel island model memetic algorithm for binary discrete tomography reconstruction that uses only four projections without any further a priori information. The underlying combination strategy consists in separated populations of agents that evolve by means of different processes. Agents progress towards a possible solution by using genetic operators, switch and a particular compactness operator. A guided migration scheme is applied to select suitable migrants by considering both their own and their sub-population fitness. That is, from time to time, we allow some individuals to transfer to different subpopulations. The benefits of this paradigm were tested in …
The Power of the “Pursuit” Learning Paradigm in the Partitioning of Data
2019
Traditional Learning Automata (LA) work with the understanding that the actions are chosen purely based on the “state” in which the machine is. This modus operandus completely ignores any estimation of the Random Environment’s (RE’s) (specified as \(\mathbb {E}\)) reward/penalty probabilities. To take these into consideration, Estimator/Pursuit LA utilize “cheap” estimates of the Environment’s reward probabilities to make them converge by an order of magnitude faster. This concept is quite simply the following: Inexpensive estimates of the reward probabilities can be used to rank the actions. Thereafter, when the action probability vector has to be updated, it is done not on the basis of th…
Accidental displacement and migration of endosseous implants into adjacent craniofacial structures: A review and update
2011
Objectives: Accidental displacement of endosseous implants into the maxillary sinus is an unusual but potential complication in implantology procedures due to the special features of the posterior aspect of the maxillary bone; there is also a possibility of migration throughout the upper paranasal sinuses and adjacent structures. The aim of this paper is to review the published literature about accidental displacement and migration of dental implants into the maxillary sinus and other adjacent structures. Study Design: A review has been done based on a search in the main on-line medical databases looking for papers about migration of dental implants published in major oral surgery, periodon…
Museums as disseminators of niche knowledge: Universality in accessibility for all
2019
Accessibility has faced several challenges within audiovisual translation Studies and gained great opportunities for its establishment as a methodologically and theoretically well-founded discipline. Initially conceived as a set of services and practices that provides access to audiovisual media content for persons with sensory impairment, today accessibility can be viewed as a concept involving more and more universality thanks to its contribution to the dissemination of audiovisual products on the topic of marginalisation. Against this theoretical backdrop, accessibility is scrutinised from the perspective of aesthetics of migration and minorities within the field of the visual arts in mu…
Perceived major experiences of discrimination, ethnic group, and risk of psychosis in a six-country case-control study
2021
AbstractBackgroundPerceived discrimination is associated with worse mental health. Few studies have assessed whether perceived discrimination (i) is associated with the risk of psychotic disorders and (ii) contributes to an increased risk among minority ethnic groups relative to the ethnic majority.MethodsWe used data from the European Network of National Schizophrenia Networks Studying Gene-Environment Interactions Work Package 2, a population-based case−control study of incident psychotic disorders in 17 catchment sites across six countries. We calculated odds ratios (OR) and 95% confidence intervals (95% CI) for the associations between perceived discrimination and psychosis using mixed-…