Influence of seed layer thickness on properties of electrodeposited ZnO nanostructured films

The quality and properties of electrodeposited nanostructured ZnO films are improved when they are deposited on a crystal lattice-matching substrate. To this end, a highly conductive indium tin oxide substrate is covered with an interlayer of ZnO using direct-current magnetron sputtering. In this manuscript, we describe the effect of this interlayer on the morphological and optical properties of several nanostructured ZnO films grown by different electrodeposition methods. The thickness of the ZnO interlayer was varied starting from ultrathin layers of 10 nm all the way up to 230 nm as determined by ellipsometry. The structural and optical properties of the nanostructured ZnO films deposited on top of these interlayers were characterized using field emission scanning electron microscopy (FESEM), atomic force microscopy and UV–visible spectroscopy. Optimum properties of the nanostructured ZnO films for application in thin-film optoelectronic devices are obtained when the ZnO interlayer has a thickness of approximately 45 nm. This is the case for all the electrodeposition methods used in this work.Facultad de Ciencias ExactasInstituto de Física La Plat

Towards stigmergic heterogenous symbiotic robot teams: enhancing RFID-based stigmergic robots for mapless environments

The study in this thesis presents new solutions for increasing the performance of RFID-based inventory robots. The first novel solution is the design of an RFID-based inventory aerial robot for the problem of stock-counting in large warehouses with very high shelves, thus, reducing the risks of human injury that accompany performing such tasks, costs, and time of operation. This robot design uses a stigmergic-based navigation algorithm to enable full autonomy in mapless environments. The second solution presented in this thesis is the development of a simulation tool that enables the robotic community to utilize RFID sensors with robots in simulation, to reduce time and costs, especially when using operational-cost expensive aerial robots. The simulation tool is based on a simplified probabilistic model that considers statistical, geometrical, and some antenna related parameters. The proposed tool is validated using various experiments in the laboratory. These validation experiments test and validate the robustness of the simulation tool with different environment layouts, the number of RFID tags in the environment, and different robot types. The third solution presented in this thesis is a localization model that is designed for distributed heterogeneous multi-robots to extend their collaboration, for solving the problem of increasing the performance of task-oriented team robots in map-less environments, this is done by exploiting the heterogeneity feature in the team. The proposed model was tested in both laboratory environments and in simulation. The simulation experiments expose the use of this model to increase the performance of a heterogeneous team of robots performing an inventory task. Finally, this thesis presents new innovative hybrid robot structure designs, that aim to amplify the abilities and features of an individual robot. The main proposed design adapts in hardware and software, the functionality of aerial and ground robots in one system, for the purpose of exploiting the beneficial characteristics that associate both robot types, at the same time mitigating the drawbacks of operating these robots individually.El estudio de esta tesis presenta nuevas soluciones para aumentar el rendimiento de los robots de inventario basados en RFID. La primera solución novedosa es el diseño de un robot aéreo de inventario basado en RFID para el problema del conteo de existencias en grandes almacenes con estantes muy altos, reduciendo así los riesgos de lesiones humanas que acompañan a la realización de tales tareas, costos y tiempo de operación. . Este diseño de robot utiliza un algoritmo de navegación basado en estigmergia para permitir una autonomía total en entornos sin mapas. La segunda solución presentada en esta tesis es el desarrollo de una herramienta de simulación que permite a la comunidad robótica utilizar sensores RFID con robots en simulación, para reducir tiempo y costos, especialmente cuando se usan robots aéreos costosos en costos operativos. La herramienta de simulación se basa en un modelo probabilístico simplificado que considera parámetros estadísticos, geométricos y algunos relacionados con la antena. La herramienta propuesta se valida mediante varios experimentos en el laboratorio. Estos experimentos de validación prueban y validan la solidez de la herramienta de simulación con diferentes diseños de entorno, la cantidad de etiquetas RFID en el entorno y diferentes tipos de robots. La tercera solución presentada en esta tesis es un modelo de localización que está diseñado para multi-robots heterogéneos distribuidos para ampliar su colaboración, para resolver el problema de aumentar el rendimiento de los robots de equipo orientados a tareas en entornos sin mapas, esto se hace mediante la explotación la característica de heterogeneidad en el equipo. El modelo propuesto fue probado tanto en ambientes de laboratorio como en simulación. Los experimentos de simulación exponen el uso de este modelo para aumentar el rendimiento de un equipo heterogéneo de robots que realizan una tarea de inventario. Finalmente, esta tesis presenta nuevos diseños innovadores de estructuras de robots híbridos, que tienen como objetivo ampliar las habilidades y características de un robot individual. El diseño principal propuesto adapta en hardware y software, la funcionalidad de los robots aéreos y terrestres en un solo sistema, con el propósito de explotar las características beneficiosas que asocian ambos tipos de robots, al mismo tiempo que mitiga los inconvenientes de operar estos robots individualmente.Programa de Doctorat en Traducció i Ciències del Llenguatg

Design of a UAV for autonomous RFID-based dynamic inventories using stigmergy for mapless indoor environments

Unmanned aerial vehicles (UAVs) and radio frequency identification (RFID) technology are becoming very popular in the era of Industry 4.0, especially for retail, logistics, and warehouse management. However, the autonomous navigation for UAVs in indoor map-less environments while performing an inventory mission is, to this day, an open issue for researchers. This article examines the method of leveraging RFID technology with UAVs for the problem of the design of a fully autonomous UAV used for inventory in indoor spaces. This work also proposes a solution for increasing the performance of the autonomous exploration of inventory zones using a UAV in unexplored warehouse spaces. The main idea is to design an indoor UAV equipped with an onboard autonomous navigation system called RFID-based stigmergic and obstacle avoidance navigation system (RFID-SOAN). RFID-SOAN is composed of a computationally low cost obstacle avoidance (OA) algorithm and a stigmergy-based path planning and navigation algorithm. It uses the same RFID tags that retailers add to their products in a warehouse for navigation purposes by using them as digital pheromones or environmental clues. Using RFID-SOAN, the UAV computes its new path and direction of movement based on an RFID density-oriented attraction function, which estimates the optimal path through sensing the density of previously unread RFID tags in various directions relative to the pose of the UAV. We present the results of the tests of the proposed RFID-SOAN system in various scenarios. In these scenarios, we replicate different typical warehouse layouts with different tag densities, and we illustrate the performance of the RFID-SOAN by comparing it with a dead reckoning navigation technique while taking inventory. We prove by the experiments results that the proposed UAV manages to adequately estimate the amount of time it needs to read up-to 99.33% of the RFID tags on its path while exploring and navigating toward new zones of high populations of tags. We also illustrate how the UAV manages to cover only the areas where RFID tags exist, not the whole map, making it very efficient, compared to the traditional map/way-points-based navigation

A ROS-based distributed multi-robot localization and orientation strategy for heterogeneous robots

The problem of estimating and tracking the location and orientation of a mobile robot by another in heterogeneous distributed multi-robots is studied in this paper. We propose a distributed multi-robot localization strategy (DMLS) that is Robotic Operating System (ROS) based. It consists of an algorithm that fuses data of diverse sensors from 2 heterogeneous robots that are not connected within their transform trees to localize and measure the relative position and orientation. The method exploits the robust detection of the Convolutional Neural Networks (CNN) and the accurate relative position measurements from the local costmap. The algorithm is composed of two parts: The localization part and the relative orientation measurement part. Localization is done by optimization and alignment calibration of the CNN output with the costmap in an individual robot. The relative orientation measurement is done by a collaborative multi-robot fusing of diverse sensor data to align and synchronize the transform frames of both robots in their costmaps. To illustrate the performance of this strategy, the proposed method is compared with a conventional object localization and orientation measuring method that uses computer vision and QR codes. The results show that this proposed method is robust and accurate while maintaining a degree of simplicity and efficiency in costs. The paper also presents various application experiments in laboratory and simulation environments. By using the proposed method, distributed multi-robots collaborate to achieve collective intelligence from individuals, which increases team performance

Influence of seed layer thickness on properties of electrodeposited ZnO nanostructured films

The quality and properties of electrodeposited nanostructured ZnO flms are improved when they are deposited on a crystal lattice-matching substrate. To this end, a highly conductive indium tin oxide substrate is covered with an interlayer of ZnO using direct-current magnetron sputtering. In this manuscript, we describe the efect of this interlayer on the morphological and optical properties of several nanostructured ZnO flms grown by diferent electrodeposition methods. The thickness of the ZnO interlayer was varied starting from ultrathin layers of 10 nm all the way up to 230 nm as determined by ellipsometry. The structural and optical properties of the nanostructured ZnO flms deposited on top of these interlayers were characterized using feld emission scanning electron microscopy (FESEM), atomic force microscopy and UV–visible spectroscopy. Optimum properties of the nanostructured ZnO flms for application in thin-flm optoelectronic devices are obtained when the ZnO interlayer has a thickness of approximately 45 nm. This is the case for all the electrodeposition methods used in this work.Fil: Reyes Tolosa, María Dolores. Universidad Politécnica de Valencia. Instituto de Tecnología de Materiales; EspañaFil: Alajami, Mutaz. Universidad Politécnica de Valencia. Instituto de Tecnología de Materiales; EspañaFil: Montero Reguera, A. E.. Universidad Politécnica de Valencia. Instituto de Tecnología de Materiales; EspañaFil: Damonte, Laura Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Hernández Fenollosa, María de los Ángeles. Universidad Politécnica de Valencia. Instituto de Tecnología de Materiales; Españ

Effective NiMn Nanoparticles-Functionalized Carbon Felt as an Effective Anode for Direct Urea Fuel Cells

The internal resistances of fuel cells strongly affect the generated power. Basically, in the fuel cell, the anode can be prepared by deposition of a film from the functional electrocatalyst on a proper gas diffusion layer. Accordingly, an interfacial resistance for the electron transport is created between the two layers. Electrocatalyst-functionalized gas diffusion layer (GDL) can distinctly reduce the interfacial resistance between the catalyst layer and the GDL. In this study, NiMn nanoparticles-decorated carbon felt is introduced as functionalized GDL to be exploited as a ready-made anode in a direct urea fuel cell. The proposed treated GDL was prepared by calcination of nickel acetate/manganese acetate-loaded carbon felt under an argon atmosphere at 850 °C. The physiochemical characterizations confirmed complete reduction for the utilized precursors and deposition of pristine NiMn nanoparticles on the carbon felt fiber. In passive direct urea fuel cells, investigation the performance of the functionalized GDLs indicated that the composition of the metal nanoparticles has to be optimized as the GDL obtained from 40 wt % manganese acetate reveals the maximum generated power density; 36 mW/m2 at room temperature and 0.5 M urea solution. Moreover, the electrochemical measurements proved that low urea solution concentration is preferred as utilizing 0.5 M solution resulted into generating higher power compared to 1.0 and 2.0 M solution. Overall, this study opens a new avenue toward functionalization of the GDL as a novel strategy to overcome the interfacial resistance between the electrocatalyst and the GDL