3,715 research outputs found
An assessment for UAS depart and approach operations
Unmanned Aerial Systems (UAS) have great potential to be used in a wide variety of civil applications such as environmental applications, emergency situations, surveillance tasks and more. The development of Flight Control Systems (FCS) coupled with the availability of other Commercial Off-The Shelf (COTS) components is enabling the introduction of UAS into the civil market. The sophistication of existing FCS is also making these systems accessible to end users with little aeronautics expertise. However, much work remains to be done to deliver systems that can be properly integrated in standard aeronautical procedures used by manned aviation.
In previous research advances have been proposed in the flight plan capabilities by offering semantically much richer constructs than those present in most current UAS autopilots. The introduced flight plan is organized as a set of stages, each one corresponding to a different flight phase. Each stage contains a structured collection of legs inspired by current practices in Area Navigation (RNAV). However, the most critical parts of any flight, the depart and approach operations in an integrated airspace remain mostly unexplored.
This paper introduces an assessment of both operations for UAS operating in VFR and IFR modes. Problems and potential solutions are proposed, as well as an automating strategy that should greatly reduce pilot workload. Although th
Surface nano-patterning through styrene adsorption on Si(100)
We present an ab initio study of the structural and electronic properties of
styrene molecules adsorbed on the dimerized Si(100) surface at different
coverages, ranging from the single-molecule to the full monolayer. The
adsorption mechanism primarily involves the vinyl group via a [2+2]
cycloaddition process that leads to the formation of covalent Si-C bonds and a
local surface derelaxation, while it leaves the phenyl group almost
unperturbed. The investigation of the functionalized surface as a function of
the coverage (e.g. 0.5 -- 1 ML) and of the substrate reconstruction reveals two
major effects. The first results from Si dimer-vinyl interaction and concerns
the controlled variation of the energy bandgap of the interface. The second is
associated to phenyl-phenyl interactions, which gives rise to a regular pattern
of electronic wires at surface, stemming from the pi-pi coupling. These
findings suggest a rationale for tailoring the surface nano-patterning of the
surface, in a controlled way.Comment: 19 pages (preprint), 4 figures, supplementary materia
Geostatistics applied to evaluation of thermal conditions and noise in compost dairy barns with different ventilation systems
ArticleThe objective of this work was to evaluate the spatial distribution of thermal
conditions and bed variables in compost dairy barns with different ventilation systems, through
the technique of geostatistics. The experiment was conducted in April 2017, in farms located in
Madre de Deus, Minas Gerais, Brazil. Three facilities were evaluated with different ventilation
systems: natural (NV); mechanical of low volume and high speed (LVHS); and mechanical of
high volume and low speed (HVLS). The interior of the premises was divided into 40 meshes
equidistant points, in which air temperature, relative humidity and air speed were manually
collected. Geostatistics technique was used to assess the spatial dependence of the variables.
The results showed the occurrence of dependence and spatial variability of the variables
evaluated. Based on thermal comfort indexes, it was concluded that dairy cows were under
stress conditions during the hottest hours of the day in the three animal facilities evaluated. The
results obtained allow us to understand that the thermal environment is more influenced by the
ventilation system adopted
Convergence of simple adaptive Galerkin schemes based on h − h/2 error estimators
We discuss several adaptive mesh-refinement strategies based on (h − h/2)-error estimation. This class of adaptivemethods is particularly popular in practise since it is problem independent and requires virtually no implementational overhead. We prove that, under the saturation assumption, these adaptive algorithms are convergent. Our framework applies not only to finite element methods, but also yields a first convergence proof for adaptive boundary element schemes. For a finite element model problem, we extend the proposed adaptive scheme and prove convergence even if the saturation assumption fails to hold in general
Colonização de fragmentos de árvores para produção de inóculo de Armillaria sp.
Organizado por Patricia Póvoa de Mattos, Celso Garcia Auer, Rejane Stumpf Sberze, Katia Regina Pichelli e Paulo César Botosso
Produção de inóculo de Trichoderma viride para o controle da armilariose em Pinus spp.
Organizado por Patricia Póvoa de Mattos, Celso Garcia Auer, Rejane Stumpf Sberze, Katia Regina Pichelli e Paulo César Botosso
Themes and criteria selection for an agro-environmental diagnosis of sugar cane production chain.
The purpose of this study was to select themes and criteria to be used in agro-environmental diagnoses of the sugar cane (Sacharum spp.) chain for ethanol production. The selection of the themes and criteria was done after a literature research; interview with specialist, participation in meetings for ethanol production and the final union of all information. As a result the following themes and criteria were selected: 1) Land use (listed as theme) ? soil and climate, land use planning, competition for food production (listed as criteria); 2) Biodiversity - disturbance of flora and fauna, planning and management of biodiversity; 3) Quality of natural resources ? residue emissions for surface and ground waters, residue emissions to the atmosphere, recycling of residues, management and conservation of soil/plant system, yield planning and traceability of the product 4) Waste generation and recycling ? water, vinasse, bagasse, straw or cover residue, oil and filter cakes and toxic waste and 5) Energy ? energetic balance, integrated ethanol and biodiesel production, energetic planning and carbon market insertion
Chirikov Diffusion in the Asteroidal Three-Body Resonance (5,-2,-2)
The theory of diffusion in many-dimensional Hamiltonian system is applied to
asteroidal dynamics. The general formulations developed by Chirikov is applied
to the Nesvorn\'{y}-Morbidelli analytic model of three-body (three-orbit)
mean-motion resonances (Jupiter-Saturn-asteroid system). In particular, we
investigate the diffusion \emph{along} and \emph{across} the separatrices of
the (5,-2,-2) resonance of the (490) Veritas asteroidal family and their
relationship to diffusion in semi-major axis and eccentricity. The estimations
of diffusion were obtained using the Melnikov integral, a Hadjidemetriou-type
sympletic map and numerical integrations for times up to years.Comment: 27 pages, 6 figure
Seleção de cultivares de alfafa em condições tropicais.
A produção de leite bovino pode ter seus custos reduzidos por meio do pastejo intensivo sob condições irrigadas, se forem utilizadas para isso forrageiras de alto potencial de produção, alto valor nutritivo e baixa estacionalidade. Uma boa opção de forrageira seria a alfafa sob pastejo, pois reduz o uso de fertilizantes nitrogenados e custo de Alimentação. No Brasil, os aspectos agronômicos dos cultivares dessa espécie ainda não são muito conhecidos para isso, o experimento teve como objetivo avaliar a resposta de 20 cultivares de alfafa sob pastejo em lotação rotacionada, durante 12 meses. Os parâmetros avaliados foram: produção de MS, estacionalidade, florescimento, relação folha: haste e sobrevivência. O delineamento experimental foi o de blocos completos casualizados. As cultivares Crioula Itapuã e Crioula RS foram consideradas materiais promissores para pastejo já que seus resultados para produção de matéria seca, número final de hastes e florescimento foram bastante satisfatórios, apesar de terem apresentado baixa relação folha:haste
Estimativas de parâmetros genéticos e fenotípicos para pesos na raça Nelore Mocha em três regiões brasileiras.
O objetivo deste trabalho foi estimar herdabilidade e correlacoes de pesoso de zebuinos Nelore Mocho. O dados foram analisados pelo metodo dos quadrados minimos, cujos metodos estatisticos incluiram os efeitos ficos de ano e estacao de nascimento, sexo, regiao, interacao estavo e regiao e a covariavel idade da vaca ao parto, o efeito aleatorio de touro.Resumos expandidos
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