Versatile model for the contact region of organic thin-film transistors

Please cite this article as: A. Romero, J. González, M.J. Deen, J.A. Jiménez-Tejada, Versatile model for the contact region of organic thin-film transistors, Organic Electronics, (2020), 77, 105523.Contact effects in organic thin film transistors (OTFTs) remain an important problem to be solved in these devices. Therefore, the correct physio-chemical modeling of the contact regions in OTFTs is necessary. In this work, a standard model for the contact region of OTFTs is proposed. It is a versatile model that describes the current-voltage characteristics of different kinds of contacts. It reproduces the behavior of Schottky barrier or space-charge limited contacts. It is a simple unified model since only a single parameter is necessary in order to distinguish between both kinds of contacts. The model is easily integrated in a generic compact model for the current-voltage characteristics of OTFTs. The resulting compact model, used in combination with an evolutionary parameter extraction procedure, allows to extract the intrinsic parameters and the current-voltage curves at the contact of single short-channel transistors. There is no need to use transistors with multiple channel lengths to accurately characterize the contact region or the active channel of the transistor. The model is tested with published experimental data of OTFTs with Schottky barrier or space-charge limited contacts. Finally, the method has been used as a diagnostic tool to analyze how an ammonia sensor reacts to different concentrations of the ammonia gas. Interestingly, alterations in the contact region have been detected when the gas concentration varies, transforming the space-charge limited contact of a pristine OTFT into a Schottky barrier contact under the exposure of gas.This work was supported by projects MAT2016-76892-C3-3-R, TIN2015-67020-P and PGC2018-098813-B-C31 funded by the Spanish Government and “European Regional Development Funds (ERDF)”. This work was also supported by NSERC Green Electronics Network (GreEN), Grant Number NETGP 508526–17

Unified electrical model for the contact regions of staggered Thin Film Transistors

In this work, we propose an unified compact model, which includes the effects of both source and drain contact regions, to describe the electrical characteristics of staggered thin film transistors (TFTs). The model is based on a generic drift analytical expression that describes the intrinsic channel of the transistor. Despite the distributed two-dimensional nature of the contacts in staggered configurations, two-terminal components are usually preferred to model the source and drain contact regions. In this regard, a model based on versatile simple expressions that describe the current-voltage relations of both contact regions are proposed in this work. These expressions are based on the physics underlying a metal-organic-metal structure. They can be adapted to different transport conditions, such as ohmic, space-charge-limited transport or Schottky-like contacts. This adaptation is controlled with the value of a single parameter that modifies the concavity or convexity of these expressions. The model works together with an evolutionary parameter extraction procedure, presented in a previous work for TFTs with negligible drain contact effects, and adapted here to this proposed model for staggered transistors. The results of the model and the evolutionary procedure have been validated with published experimental data of different TFTs, mostly organic thin film transistors (OTFTs). The model and evolutionary procedure agrees with other procedures tested successfully in the literature which were defined to cope with specific kinds of contacts in the TFTs. In this regard, our model and evolutionary parameter extraction procedure unify these previous procedures.Departamento de Electrónica y Tecnología de Computadore

Hydrologic Modeling Analysis from Land Use Scenario Changes in Quebrada Seca and Bermudez Watershed

During the last few years, the expansion of urban cover in the Quebrada Seca-Bermudez watershed has caused a series of floods that have damaged houses, bridges, and other important infrastructure of the area. Hence local governments need a more precise description of these extreme rainfall events through reliable data and modeling watershed, based on 3 different storm durations and five different scenarios: three scenarios from previous years (2001, 2008, and 2012) and 2 forecasted scenarios for the year 2020 (one according to the projected urban growth and the other one based on local urban regulations). Land cover variations were determined using Lansat 7ETM+ images. Both supervised and unsupervised classifications were applied to the satellite images and 6 common classes were obtained: forest, crops, pasture, urban, bare soil and industrial. The Curve Number was assigned based on this information and the soil data with a 1:20 000 scale resolution. A digital elevation model (DEM) with a 30 meters resolution was used to calculate the watershed parameters. Rainfall data over a period of almost 15 years from three meteorological stations were analyzed in order to obtain 2-, 5-, 10-and 25-year return periods. Discharge for all the scenarios was calculated with HEC-HMS program in order to evaluate the changes of urban growth. The results showed a rate of impervious cover of 27% for scenario 1 and 55% for scenario 2. The flow discharge increase for the year2020 is expected to bebetween1% to 14.9% for scenario1.Universidad de Costa Rica/[731-B4-212]/UCR/Costa RicaUCR::Vicerrectoría de Docencia::Ingeniería::Facultad de Ingeniería::Escuela de Ingeniería de BiosistemasUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ingeniería::Instituto Investigaciones en Ingeniería (INII

Sprint performance and mechanical outputs computed with an iPhone app: Comparison with existing reference methods

The purpose of this study was to assess validity and reliability of sprint performance outcomes measured with an iPhone application (named: MySprint) and existing field methods (i.e. timing photocells and radar gun). To do this, 12 highly trained male sprinters performed 6 maximal 40-m sprints during a single session which were simultaneously timed using 7 pairs of timing photocells, a radar gun and a newly developed iPhone app based on high-speed video recording. Several split times as well as mechanical outputs computed from the model proposed by Samozino et al. [(2015). A simple method for measuring power, force, velocity properties, and mechanical effectiveness in sprint running. Scandinavian Journal of Medicine & Science in Sports. https://doi.org/10.1111/sms.12490] were then measured by each system, and values were compared for validity and reliability purposes. First, there was an almost perfect correlation between the values of time for each split of the 40-m sprint measured with MySprint and the timing photocells (r = 0.989–0.999, standard error of estimate = 0.007–0.015 s, intraclass correlation coefficient (ICC) = 1.0). Second, almost perfect associations were observed for the maximal theoretical horizontal force (F0), the maximal theoretical velocity (V0), the maximal power (Pmax) and the mechanical effectiveness (DRF – decrease in the ratio of force over acceleration) measured with the app and the radar gun (r = 0.974–0.999, ICC = 0.987–1.00). Finally, when analysing the performance outputs of the six different sprints of each athlete, almost identical levels of reliability were observed as revealed by the coefficient of variation (MySprint: CV = 0.027–0.14%; reference systems: CV = 0.028–0.11%). Results on the present study showed that sprint performance can be evaluated in a valid and reliable way using a novel iPhone app.Actividad Física y Deport

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Differences between adjusted vs. non- adjusted loads in velocity-based training: consequences for strength training control and programming

Strength and conditioning specialists commonly deal with the quantification and selection the setting of protocols regarding resistance training intensities. Although the one repetition maximum (1RM) method has been widely used to prescribe exercise intensity, the velocity-based training (VBT) method may enable a more optimal tool for better monitoring and planning of resistance training (RT) programs. The aim of this study was to compare the effects of two RT programs only differing in the training load prescription strategy (adjusting or not daily via VBT) with loads from 50 to 80% 1RM on 1RM, countermovement (CMJ) and sprint. Twenty-four male students with previous experience in RT were randomly assigned to two groups: adjusted loads (AL) (nD13) and non-adjusted loads (NAL) (nD11) and carried out an 8-week (16 sessions) RT program. The performance assessment pre- and post-training program included estimated 1RM and full load-velocity profile in the squat exercise; countermovement jump (CMJ); and 20-m sprint (T20). Relative intensity (RI) and mean propulsive velocity attained during each training session (Vsession) was monitored. Subjects in the NAL group trained at a significantly faster Vsession than those in AL (p < 0.001) (0.88 - 0.91 vs. 0.67- 0.68 m/s, with a 15% RM gap between groups for the last sessions), and did not achieve the maximum programmed intensity (80% RM). Significant differences were detected in sessions 3- 4, showing differences between programmed and performed Vsession and lower RI and velocity loss (VL) for the NAL compared to the AL group (p < 0.05). Although both groups improved 1RM, CMJ and T20, NAL experienced greater and significant changes than AL (28.90 vs.12.70%, 16.10 vs. 7.90% and -1.99 vs. - 0.95%, respectively). Load adjustment based on movement velocity is a useful way to control for highly individualised responses to training and improve the implementation of RT programs

La perspectiva de familia en los planes de desarrollo municipal: un estudio descriptivo desde el contexto territorial en 26 municipios de Boyacá

La investigación realizada presenta un análisis de la inclusión del concepto de familia en 26 planes de desarrollo municipal del departamento de Boyacá para el periodo 2020 – 2023. La metodología utilizada se basó en el análisis documental de dichos planes de desarrollo desde las categorías de familia y política pública en el contexto territorial municipal. Como resultados se identificaron tres aspectos que permiten evidenciar las condiciones de las familias boyacenses y la atención a las mismas: la incidencia de la violencia intrafamiliar y sus factores de riesgo, la promoción de normatividad orientada a la protección integral de las familias y las estrategias ejercidas y/o proyectadas por las entidades territoriales respondiendo a las necesidades de las mismas, su garantía de derechos y la prevención de cualquier tipo de violencia al interior del hogar, especialmente en la adopción de acciones de prevención en tiempos de confinamiento donde la problemática se agudizó a nivel departamental y nacional

Strong Metal-Support Interaction (SMSI) in Au/TiO2 photocatalysts for environmental remediation applications: Effectiveness enhancement and side effects

Strong Metal−Support Interaction (SMSI) is a well-known phenomenon of heterogeneous catalysis that have not been extensively investigated in photocatalytic applications. Moreover, the reactions previously studied for photocatalysts under SMSI state are mainly restricted to energy related uses. The present work seeks to explore the effect of SMSI induced by soft wet-chemistry in a Au/TiO2 photocatalyst with specific focus on photocatalytic environmental remediation. With this aim, the developed photocatalyst has been evaluated considering liquid, gas and solid pollutants in order to represent the wide range of environmental photocatalysis applications. These photooxidation scenarios were methylene blue dissolved in water, gaseous NO, and soot directly deposited on the photocatalyst. The results revealed that the SMSI induction has a generally positive effect on photoactivity promoting the MB and soot removal by 53% and 60%, respectively. However, the SMSI did not provide any additional benefit in the NOx elimination compared to the non-SMSI Au/TiO2 photocatalyst, because the enveloping of AuNPs limits the gold-pollutant interaction