Autonomous Navigation System for a Delivery Drone

The use of delivery services is an increasing trend worldwide, further enhanced by the COVID pandemic. In this context, drone delivery systems are of great interest as they may allow for faster and cheaper deliveries. This paper presents a navigation system that makes feasible the delivery of parcels with autonomous drones. The system generates a path between a start and a final point and controls the drone to follow this path based on its localization obtained through GPS, 9DoF IMU, and barometer. In the landing phase, information of poses estimated by a marker (ArUco) detection technique using a camera, ultra-wideband (UWB) devices, and the drone's software estimation are merged by utilizing an Extended Kalman Filter algorithm to improve the landing precision. A vector field-based method controls the drone to follow the desired path smoothly, reducing vibrations or harsh movements that could harm the transported parcel. Real experiments validate the delivery strategy and allow to evaluate the performance of the adopted techniques. Preliminary results state the viability of our proposal for autonomous drone delivery.Comment: 12 pages, 15 figures, extended version of an paper published at the XXIII Brazilian Congress of Automatica, entitled "Desenvolvimento de um drone aut\^onomo para tarefas de entrega de carga

A comparative phylogenomic analysis of birds reveals heterogeneous differentiation processes among Neotropical savannas

The main objective of this study was to evaluate biogeographical hypotheses of diversification and connection between isolated savannas north (Amazonian savannas) and south (Cerrado core) of the Amazon River. To achieve this, we used genomic markers (genotyping-by-sequencing) to evaluate the genetic structure, population phylogenetic relationships and historical range shifts of four Neotropical passerines with peri-Atlantic distributions: the narrow-billed woodcreeper (Lepidocolaptes angustirostris), the plain-crested elaenia (Elaenia cristata), the grassland sparrow (Ammodramus humeralis) and the white-banded tanager (Neothraupis fasciata). Population genetic analyses indicated that landscape (e.g., geographic distance, landscape resistance and percentage of tree cover) and climate metrics explained divergence among populations in most species, but without indicating a differential role between current and historical factors. Our results did not fully support the hypothesis that isolated populations in Amazonian savannas have been recently derived from the Cerrado core domain. Intraspecific phylogenies and gene flow analyses supported multiple routes of connection between the Cerrado and Amazonian savannas, rejecting the hypothesis that the Atlantic corridor explains the peri-Atlantic distribution. Our results reveal that the biogeographical history of the region is complex and cannot be explained by simple vicariant models.Fil: Alves Lima Rezende, Cássia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Cabanne, Gustavo Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Rocha, Amanda Vaz. Universidade do Brasília; BrasilFil: Carboni, Martín Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Zink, Robert M.. University of Nebraska; Estados UnidosFil: Caparroz, Renato. Universidade do Brasília; Brasi

Electrochemical degradation of the chloramphenicol at flow reactor

This paper reports a study of electrochemical degradation of the chloramphenicol antibiotic in aqueous medium using a flow-by reactor with DSA® anode. The process efficiency was monitored by chloramphenicol concentration analysis with liquid chromatography (HPLC) during the experiments. Analysis of Total Organic Carbon (TOC) was performed to estimate the degradation degree and Ion Chromatography (IC) was performed to determinate inorganic ions formed during the eletrochemical degradation process. In electrochemical flow-by reactor, 52% of chloramphenicol was degraded, with 12% TOC reduction. IC analysis showed the production of chloride ions (25 mg L-1), nitrate ions (6 mg L-1) and nitrite ions (4.5 mg L-1).Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Uso de un sistema de ahorro de agua para conservar ecosistemas para el recurso hídrico

En la región noroeste de la república mexicana, zona fronteriza entre México y Estados Unidos (EE.UU.), se está evaluando una posible problemática de la escasa cantidad de agua que México recibe de su vecino del norte, proveniente del Río Colorado (RC). En ocasiones, México recibe agua contaminada por agroquímicos debido a que ese recurso hídrico proviene del lavado de tierras estadounidenses. Además, Estados Unidos propuso revestir el Canal Todo Americano (CTA), lo que ha generado una disminución en los mantos acuíferos del valle de Mexicali, generando preocupación en autoridades y la población. Esto ha conllevado a deteriorar ecosistemas y con ello presentarse cambios de clima que incrementan los niveles de humedad relativa (HR) y temperatura, que genera corrosión y pérdidas económicas, y reducción de la competitividad en la industria electrónica de la región

Youth and Political Participation: #YoSoy132 and the Struggle for Freedom of Expression in Mexico

The mobilization of the student movement #YoSoy132 inspired new political and civic participation among young students in the urban context of Mexico City. This study explores the habits and perspectives around political participation, freedom of expression, and the use of social networks among these university students. Based on survey data from two samples, we contrast the relationship between online and offline political practices during the birth of #YoSoy132. For the first sample, we administered a questionnaire to college students who took part in a public demonstration organized by the #YoSoy132 movement just one week before the 2012 Mexican federal election. We collected the second sample via social media online, with a focus on college students from different universities across Mexico City. We compare the similarities and differences across youth participation via the samples In Situ and Online groups. We demonstrate that digital penetration and the presence of a convergent culture are important elements that favor hybrid political and civil participation. Our findings allow us to infer, at least from our samples of college students, that social networks are gaining unprecedented importance in the formation of youth imaginaries when a strong correlation between online and offline practices exists. In the face of widespread accusations of the corruption of mass media in Mexico and systemic threats to freedom of expression, social networks provided an alternative and trustworthy route for expression, dialogue, and mobilization

Supramolecular self-assembly of a new multi-conformational Schiff base through hydrogen bonds: Crystal structure, spectroscopic and theoretical investigation

The compound 4-(4-dimethylaminobenzylidene)aminoacetophenone was synthesized by condensation of 4-aminoacetophenone and 4-(dimethylamino) benzaldehyde in ethanol. This compound was characterized by CG-MS, infrared, Raman, UVeVis, 1H and 13C NMR spectroscopy. The crystal structure was solved by single-crystal X-ray diffraction methods. The crystallographic data reveals that there are four independent molecules per asymmetric unit, that mainly differ from one another in rotations around the σ-bond of the azomethine N-atom with the phenyl ring. A detailed analysis of the intermolecular interactions in the four conformers of the compound has been performed using Hirshfeld surfaces and their associated two-dimensional fingerprint plots. The optimized geometrical parameters and calculated spectroscopic features obtained by quantum chemical calculations at B3LYP method show a very good agreement with the experimental data. Moreover, Natural Bond Orbital (NBO) analysis confirms the strong hyper-conjugative LP N(n1) → σ* C(n9)–H interaction between the lone pair located in the N-atom of the azomethine group and the C–H bond. Liquid crystalline properties of the Schiff base were studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and Powder X-ray diffraction techniques. Mesomorphic behaviour was observed in this unsymmetrical azomethine. Based on POM and DSC measurements, the hexatic Smetic B phase was detected.Facultad de Ciencias ExactasCentro de Química InorgánicaInstituto de Física La Plat