604 research outputs found
Acanthagrion marinae sp. Nov. (zygoptera: Coenagrionidae): A new species of the apicale group
Acanthagrion marinae sp. nov. (Holotype male: BRASIL, Mato Grosso do Sul, Campo Grande, UFMS, 20°29’56.26’’S-54°36’48.43’’W, 547m, leg. M.E. Rodrigues, 03.ii.2015, collection code: VZYG437, MLP) is described and illustrated on the basis of 15 males. The new species belongs to the apicale species group by having horns on S10 and sclerotized hooks on tip of distal segment of the genital ligula. It can be easily distinguished from other species of the group by a combination of characters of the genital ligulae (presence of setae on segment two; absence of setae at flexure; distal lateral lobes of segment three absent). Notes on habitat and a modification of previous keys for the species of the apicale group are provided.Fil: Lozano, Federico. Universidad Nacional de Avellaneda. Departamento de Ciencias Ambientales; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Rodrigues, Marciel E. Universidade Estadual de Santa Cruz; Brasi
Description of the final instar larva of argia serva hagein selys, 1865 (Odonata coenagrionidae)
The American genus Argia, with more than 100 species described, is the most speciose genus of Odonata in the world. In this contribution, the final stadium larva of Argia serva, the southernmost distributed species of Argia, is described and diagnosed based on reared material from MartĂn GarcĂa island, Buenos Aires, Argentina. The larva of this species can be easily separated from the other Argentinean Argia by the following combination of characters: sternum of S8 covered with spines (bare in A. translata); antennal segment 3 longer than 1+2 (equal to or shorter than 1+2 in A. joergenseni and A. jujuya); palpal setae absent (present in A. croceipennis). A key to the known larvae of Argia of the Southern Cone is provided.Fil: del Palacio, Alejandro. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Avellaneda. Departamento de Ciencias Ambientales; ArgentinaFil: Lozano, Federico. Universidad Nacional de Avellaneda. Departamento de Ciencias Ambientales; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: MuzĂłn, Javier. Universidad Nacional de Avellaneda. Departamento de Ciencias Ambientales; Argentin
The rise of SOL - Sociedad(e) de OdonatologĂa Latinoamericana
In the last decades, odonatology in Latin Americahas had a notable improvement in the number ofresearchers and students from within Latin Americancountries studying Odonata biology, ecology andsystematics.This improvement together with theoverwhelming diversity of the region not only hasconsolidated the integration among Latin Americancountries, but also made possible the integration ofLatin America into the international scenario. Thisis evidenced by the election of two Latin Americancities as venues for the International Congress ofOdonatology (Xalapa, Mexico in 2009, and BuenosAires, Argentina in 2015)Fil: Muzon, Javier. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Avellaneda. Departamento de Ciencias Ambientales; ArgentinaFil: Ferreira Rhainer, Guillermo. Universidade Federal do SĂŁo Carlos; BrasilFil: Lozano, Federico. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Avellaneda. Departamento de Ciencias Ambientales; Argentin
Numerical integration of the stochastic Landau-Lifshitz-Gilbert equation in generic time-discretisation schemes
We introduce a numerical method to integrate the stochastic
Landau-Lifshitz-Gilbert equation in spherical coordinates for generic
discretization schemes. This method conserves the magnetization modulus and
ensures the approach to equilibrium under the expected conditions. We test the
algorithm on a benchmark problem: the dynamics of a uniformly magnetized
ellipsoid. We investigate the influence of various parameters, and in
particular, we analyze the efficiency of the numerical integration, in terms of
the number of steps needed to reach a chosen long time with a given accuracy.Comment: 9 pages and 7 figure
Los Juegos florales de Ronda en 1911
Datos recogidos de la cub.Copia digital : Diputación de Málaga. Biblioteca Canovas del Castillo, 201
Optimization of refinery preheat trains undergoing fouling: control, cleaning scheduling, retrofit and their integration
Crude refining is one of the most energy intensive industrial operations. The large amounts of crude processed, various sources of inefficiencies and tight profit margins promote improving energy recovery. The preheat train, a large heat exchanger network, partially recovers the energy of distillation products to heat the crude, but it suffers of the deposition of material over time – fouling – deteriorating its performance. This increases the operating cost, fuel consumption, carbon emissions and may reduce the production rate of the refinery.
Fouling mitigation in the preheat train is essential for a profitable long term operation of the refinery. It aims to increase energy savings, and to reduce operating costs and carbon emissions. Current alternatives to mitigate fouling are based on heuristic approaches that oversimplify the representation of the phenomena and ignore many important interactions in the system, hence they fail to fully achieve the potential energy savings. On the other hand, predictive first principle models and mathematical programming offer a comprehensive way to mitigate fouling and optimize the performance of preheat trains overcoming previous limitations.
In this thesis, a novel modelling and optimization framework for heat exchanger networks under fouling is proposed, and it is based on fundamental principles. The models developed were validated against plant data and other benchmark models, and they can predict with confidence the main effect of operating variables on the hydraulic and thermal performance of the exchangers and those of the network.
The optimization of the preheat train, an MINLP problem, aims to minimize the operating cost by: 1) dynamic flow distribution control, 2) cleaning scheduling and 3) network retrofit. The framework developed allows considering these decisions individually or simultaneously, although it is demonstrated that an integrated approach exploits the synergies among decision levels and can reduce further the operating cost. An efficient formulation of the model disjunctions and time representation are developed for this optimization problem, as well as efficient solution strategies. To handle the combinatorial nature of the problem and the many binary decisions, a reformulation using complementarity constraints is proposed. Various realistic case studies are used to demonstrate the general applicability and benefits of the modelling and optimization framework. This is the first time that first principle predictive models are used to optimize various types of decisions simultaneously in industrial size heat exchanger networks.
The optimization framework developed is taken further to an online application in a feedback loop. A multi-loop NMPC approach is designed to optimize the flow distribution and cleaning scheduling of preheat trains over two different time scales. Within this approach, dynamic parameter estimation problems are solved at frequent intervals to update the model parameters and cope with variability and uncertainty, while predictive first principle models are used to optimize the performance of the network over a future horizon. Applying this multi-loop optimization approach to a case study of a real refinery demonstrates the importance of considering process variability on deciding about optimal fouling mitigation approaches. Uncertainty and variability have been ignored in all previous model based fouling mitigation strategies, and this novel multi-loop NMPC approach offers a solution to it so that the economic savings are enhanced.
In conclusion, the models and optimization algorithms developed in this thesis have the potential to reduce the operating cost and carbon emission of refining operations by mitigating fouling. They are based on accurate models and deterministic optimization that overcome the limitations of previous applications such as poor predictability, ignoring variability and dynamics, ignoring interactions in the system, and using inappropriate tools for decision making.Open Acces
Negragrion sagma gen.n. and sp.n. from South America with a morphological phylogeny of the New World Ischnurinae (Odonata: Zygoptera: Coenagrionidae)
A new coenagrionid genus, Negragrion, is described for N. sagma sp.n. found in Argentina and Brazil (Holotype and allotype, pair in tandem. Argentina: Corrientes: Santo TomĂ©, arroyo Ita Cuá sobre RP 94, 28°26’48.30”S 56°00’33.11”W, 24.ii.2003, MuzĂłn & Pessacq coll., MLP). The new genus is characterized by the shape of male cerci (decumbent from base; saddle-shaped; in lateral view with an acute apophysis directed dorsally located at 0.3 from base). The presence of a vulvar spine on S8 of females places this genus within Ischnurinae. A cladistics analysis using morphological data was carried out to determine its phylogenetic position. Negragrion gen.n. is recovered within the clade 4 as the sister group of the clade (Acanthallagma Acanthagrion (Oxyagrion, Fluminagrion)).Fil: Muzon, Javier. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Avellaneda; ArgentinaFil: Lozano, Federico. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Avellaneda; Argentin
Acanthagrion hartei sp. nov. from Ecuador (Zygoptera: Coenagrionidae)
The new sp. is described and illustrated. Holotype ♂; Ecuador, Morona, Santiago prov., Bomboiza, 20-IX-1990, deposited in USNM, Washington. It is assigned to the apicale-group, and differs from the other spp. of that group by characters of the ♂ terminalia and genital ligulaInstituto de LimnologĂa "Dr. RaĂşl A. Ringuelet
Acanthagrion hartei sp. nov. from Ecuador (Zygoptera: Coenagrionidae)
The new sp. is described and illustrated. Holotype: Ecuador, Morona, Santiago prov., Bomboiza, 20-IX-1990, deposited in USNM, Washington. It is assigned to the apicale-group, and differs from the other spp. of that group by characters of the terminalia and genital ligula.
Fil: Muzon, Javier. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de LimnologĂa ; ArgentinaFil: Lozano, Federico. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de LimnologĂa ; Argentin
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