Lattice Boltzmann simulations of droplet dynamics in time-dependent flows

We study the deformation and dynamics of droplets in time-dependent flows using 3D numerical simulations of two immiscible fluids based on the lattice Boltzmann model (LBM). Analytical models are available in the literature, which assume the droplet shape to be an ellipsoid at all times (P.L. Maffettone, M. Minale, J. Non-Newton. Fluid Mech 78, 227 (1998); M. Minale, Rheol. Acta 47, 667 (2008)). Beyond the practical importance of using a mesoscale simulation to assess ab-initio the robustness and limitations of such theoretical models, our simulations are also key to discuss - in controlled situations - some relevant phenomenology related to the interplay between the flow time scales and the droplet time scales regarding the transparency transition for high enough shear frequencies for an external oscillating flow. This work may be regarded as a step forward to discuss extensions towards a novel DNS approach, describing the mesoscale physics of small droplets subjected to a generic hydrodynamical strain field, possibly mimicking the effect of a realistic turbulent flow on dilute droplet suspensions

A smooth entropy approach to quantum hypothesis testing and the classical capacity of quantum channels

We use the smooth entropy approach to treat the problems of binary quantum hypothesis testing and the transmission of classical information through a quantum channel. We provide lower and upper bounds on the optimal type II error of quantum hypothesis testing in terms of the smooth max-relative entropy of the two states representing the two hypotheses. Using then a relative entropy version of the Quantum Asymptotic Equipartition Property (QAEP), we can recover the strong converse rate of the i.i.d. hypothesis testing problem in the asymptotics. On the other hand, combining Stein's lemma with our bounds, we obtain a stronger (\ep-independent) version of the relative entropy-QAEP. Similarly, we provide bounds on the one-shot \ep-error classical capacity of a quantum channel in terms of a smooth max-relative entropy variant of its Holevo capacity. Using these bounds and the \ep-independent version of the relative entropy-QAEP, we can recover both the Holevo-Schumacher-Westmoreland theorem about the optimal direct rate of a memoryless quantum channel with product state encoding, as well as its strong converse counterpart.Comment: v4: Title changed, improved bounds, both direct and strong converse rates are covered, a new Discussion section added. 20 page

Desempenho energético de uma produção de eucalipto

Maximizing yields is opposed to the goal of minimizing the use of inputs. In the context of system rationalization, the addition of non-economic parameters in the decision making and the magnitude of eucalyptus plantation in Sao Paulo State, Brazil led to this study. The objective was to establish the flows and to evaluate the performance of energy transformations on eucalyptus production. The evaluated system presented three alternatives of soil acidity management: lime, ash and sludge application. The applied indicators were energy return on investment, energy intensity and energy balance, which meant, respectively, the return over energy investment, the energy content of biomass and the energy obtained per area. For the basic scenario, lime, EROI was 58.5 MJ MJ-1, energy intensity was 124.7 MJ m-3, and the energy balance was 2120.7 GJ ha-1. The required energy was larger when ash (5.2%) and sludge (57.2%) were used. The main inputs were, in order, fuel, fertilizers, herbicide and lime. Harvesting was the main operation (56.7%), followed by subsoiling. Fuel in harvesting, fertilizers and lime summed 79.6% of the total energy. The sensitivity of the system showed that the material used to control soil acidity had more effect on the energy demand (up to +57.4%) than the suggested scenarios (-5.3% when the field efficiency was increased).O contexto da racionalização dos sistemas de produção, a inserção de parâmetros não-econômicos na tomada de decisão e a magnitude do cultivo de eucalipto, no Estado de São Paulo, Brasil, nortearam este estudo, cujo objetivo foi estabelecer os fluxos e o desempenho das transformações energéticas de um sistema de produção de eucalipto. O sistema avaliado apresentou três alternativas de manejo de acidez do solo: calcário, cinzas e biossólido. Os indicadores utilizados foram o retorno de energia sobre energia investida, intensidade e balanço energéticos, que representam, respectivamente, a taxa de retorno de energia obtida, a energia contida na biomassa e a energia obtida por área. Para o cenário básico, calcário, o retorno de energia sobre energia investida foi de 58,5 MJ MJ-1, a intensidade energética da biomassa 124,7 MJ m-3 e o balanço de energia foi 2120,7 GJ ha-1. A energia demandada foi maior com cinzas (5,2%) e biossólido (57,2%). Os principais insumos foram, em ordem decrescente: combustível, fertilizantes, herbicida e calcário. A colheita é a principal operação (56,7%), seguida da subsolagem. O combustível gasto na colheita mais fertilizantes e calcário correspondem a 79,6% da energia necessária. A sensibilidade do sistema mostrou que o material de controle de acidez do solo causa maiores efeitos na demanda de energia (até +57,4%) que os cenários sugeridos (-5,3% com acréscimo da eficiência de campo).Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES