Reflection and transmission in the ionosphere considering collisions in a first approximation

Reflection and transmission coefficients (R and T) of high frequency waves propagating in the ionosphere are studied taking collisions into account. This was done approximating the expression in the refractive index using binomial expansion and neglecting terms of order higher than is the ratio between the electron collision frequency and the wave frequency. R and T height profiles were assessed using the International Reference Ionosphere, IRI, to estimate the ionosphere plasma parameters. Although no significant differences are found between the estimation with and without collisions, the method employed to include collisions may be useful for other purposes where collisions should be taken into account.Fil: Yesil, Ali. Firat University; TurquíaFil: Aydogdu, Mehmet. Firat University; TurquíaFil: Elias, Ana Georgina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Metal-insulator transition and electrically-driven memristive characteristics of SmNiO3 thin films

The correlated oxide SmNiO3 (SNO) exhibits an insulator to metal transition (MIT) at 130 {\deg}C in bulk form. We report on synthesis and electron transport in SNO films deposited on LaAlO3 (LAO) and Si single crystals. X-ray diffraction studies show that compressively strained single-phase SNO grows epitaxially on LAO while on Si, mixed oxide phases are observed. MIT is observed in resistance-temperature measurements in films grown on both substrates, with charge transport in-plane for LAO/SNO films and out-of-plane for Si/SNO films. Electrically-driven memristive behavior is realized in LAO/SNO films, suggesting that SNO may be relevant for neuromorphic devices

An analysis of IEEE 802.11 DCF and its application to energy-efficient relaying in multihop wireless networks

Cataloged from PDF version of article.We present an analytical model for the IEEE 802.11 DCF in multihop wireless networks that considers hidden terminals and accurately works for a large range of traffic loads. An energy model, which considers energy consumption due to collisions, retransmissions, exponential backoff and freezing mechanisms, and overhearing of nodes, and the proposed IEEE 802.11 DCF analytical model are used to analyze the energy consumption of various relaying strategies. The results show that the energy-efficient relaying strategy depends significantly on the traffic load. Under light traffic, energy spent during idle mode dominates, making any relaying strategy nearly optimal. Under moderate traffic, energy spent during idle and receive modes dominates and multihop transmissions become more advantageous where the optimal hop number varies with processing power consumed at relay nodes. Under very heavy traffic, where multihopping becomes unstable due to increased collisions, direct transmission becomes more energy efficient. The choice of relaying strategy is observed to affect energy efficiency more for large and homogeneous networks where it is beneficial to use multiple short hops each covering similar distances. The results indicate that a cross-layered relaying approach, which dynamically changes the relaying strategy, can substantially save energy as the network traffic load changes in time. © 2011 IEEE

Coding Activities for Children with Autism: A Sample Application

Purpose The research was conducted to test the effects of coding activities on the development of children with autism Method Five children aged 6-8 who received education from a special education application center in Erzincan city center participated in the research In the study coding activities consisting of four sessions two sessions a week were made for two weeks Coding activities consist of shadow finding mate finding pattern creation and completion activities Dunn Sensory Profile for mothers in order to determine the effect of coding activities Interview Form and Questionnaire for teachers Concept Evaluation Form was applied to children Results As a result of the research it was determined that coding activities increased the multi-sensory processing attention visual perception interest and acting in accordance with instructions motor hand-eye coordination imitation ability interest fun memory retention eye contact and conceptual skills of children with autism In addition it was determined that children with autism increased their ability to match and complete objects find the shadow of objects and create patterns in relation to the application Discussion and Recommodation In line with the results it is recommended that coding activities be integrated into the educational environments of children with autis