18,513 research outputs found
Comparação de ferramentas de tópicos em textos sob o paradigma de aprendizado estatístico não supervisionado.
Neste trabalho pretende-se estudar e explorar ferramentas de aprendizado de tópicos hierárquicos, através de coleções textuais e teoria estatísticaCIIC 2014. Nº 14602
Mimosoideae (Leguminosae) importantes para o manejo florestal no estado do Pará.
Leguminosae está representada por três subfamílias, 727 gêneros e 19.325 espécies, com distribuição cosmopolita. Mimosoideae possui cerca de 3.270 espécies circunscritas em quatro tribos, com 78 gêneros. Devido à ampla distribuição geográfica das Leguminosae na Amazônia e ao potencial econômico apresentado por diversas espécies, o estudo dessa família torna-se muito importante para a região. O presente trabalho teve como objetivo listar as espécies de Mimosoideae importantes para o manejo florestal no Pará e indicar suas respectivas áreas de ocorrência nesse Estado, visando contribuir para planos de manejo regionais. Inicialmente, preparou-se uma lista das Mimosoideae comercializadas no Pará, a qual foi baseada na lista oficial da SEMA (Secretaria de Estado de Meio Ambiente - PA) inerente às espécies produtoras de madeireira, complementada pela lista do IBAMA e de algumas madeireiras do Estado e das amostras de madeira que chegam à Xiloteca da Embrapa Amazônia Oriental. Os herbários IAN, INPA, MG, RB e RON foram consultados a fim de obter informações sobre local de coleta das espécies da lista. Todas essas informações foram incorporadas em um banco de dados; também estão sendo incluídas as coordenadas geográficas dos respectivos locais de coleta. A lista de espécies de Mimosoideae importantes para o manejo florestal no Pará corresponde a 40 espécies circunscritas em 16 gêneros, as quais se encontram registrados em 2.228 exemplares nos herbários consultados
On optimizing a WWTP design using multi-objective approaches
In this paper, the multi-objective formulation of
an optimization problem arising from an activated sludge
(AS) system of a wastewater treatment plant (WWTP) design
optimization is solved through a multi-objective genetic algorithm.
Two multi-objective approaches are proposed. First, a
solution to the WWTP design is provided, regardless of its
location, date of construction or the involved unit operations.
The variables that mostly influence the cost of the system define
the objectives and are simultaneously optimized. Second, two
crucial objectives for the correct operation of the AS system
are simultaneously optimized: the investment and operation
costs are minimized and the effluent quality is maximized.
Since the objectives are conflicting, several trade-offs between
objectives are obtained through the optimization process. The
direct visualization of the trade-offs through Pareto curves
assists the decision-maker in the selection of crucial design
and operation variables. The numerical results show that the
proposed methodology produces improved results with physical
meaning when compared with previous work.Fundação para a Ciência e a Tecnologia (FCT
Recovery of platinum(IV) and palladium(II) from complex hydrochloric acid matrices by a thiodiglycolamide derivative
The solvent extraction performance of N,N’-dimethyl-N,N’-dicyclohexylthiodiglycolamide (DMDCHTDGA) towards Pt(IV) and Pd(II) in HCl solutions has recently been published. It was shown that these two platinum-group metals (PGMs) are efficiently extracted from 8 M HCl aqueous phases, being subsequently separated by sequential strippings: 1 M HCl allows Pt(IV) recovery, whereas Pd(II) is only back-extracted by thiourea in HCl. In this work, selectivity tests were carried out to evaluate the performance of DMDCHTDGA towards the recovery of both PGMs, from 8 M HCl aqueous phases, when in presence of Rh(III), Fe(III), Ni(II), Zn(II), Al(III), Ce(III) and Zr(IV), simulating the leaching solutions that may result from the hydrometallurgical treatment of spent automobile catalytic converters. It was generally observed
that the additional metal ions do not affect the recovery of Pd(II) and Pt(IV) by DMDCHTDGA. Fe(III), Zn(II) and Zr(IV) are co-extracted with Pt(IV) and Pd(II); Fe(III) and Zn(II) were efficiently scrubbed with water, whereas Zr(IV) was removed by an acidified aqueous solution. Inversely, Ni(II) is not extracted, and Rh(III) and Ce(III) appear only traceably in the loaded organic phase. Al(III) is a concern, as it is appreciably extracted, and none of the tested backextraction solutions was able to strip it
A hybrid genetic pattern search augmented Lagrangian method for constrained global optimization
Hybridization of genetic algorithms with local search approaches can enhance their performance in global optimization. Genetic algorithms, as most population based algorithms, require a considerable number of function evaluations. This may be an important drawback when the functions involved in the problem are computationally expensive as it occurs in most real world problems. Thus, in order to reduce the total number of function evaluations, local and global techniques may be combined. Moreover, the hybridization may provide a more effective trade-off between exploitation and exploration of the search space. In this study, we propose a new hybrid genetic algorithm based on a local pattern search that relies on an augmented Lagrangian function for constraint-handling. The local search strategy is used to improve the best approximation found by the genetic algorithm. Convergence to an -global minimizer is proved. Numerical results and comparisons with other stochastic algorithms using a set of benchmark constrained problems are provided.FEDER COMPETEFundação para a Ciência e a Tecnologia (FCT
Hábito de crescimento, coloração da inflorescência e caracterização da folha em germoplasma de mangueira em Juazeiro-BA.
O presente trabalho teve como objetivo a caracterização de acessos de mangueira (Mangifera indica L.) em relação ao hábito de crescimento, coloração da inflorescência, formato da folha, formato da base da folha e formato do ápice da folha
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