Evaluating Distributed Time-Varying Generation Through a Multiobjective Index

In the last decade, distributed generation, with its various technologies, has increased its presence in the energy mix presenting distribution networks with challenges in terms of evaluating the technical impacts that require a wide range of network operational effects to be qualified and quantified. The inherent time-varying behavior of demand and distributed generation (particularly when renewable sources are used), need to be taken into account since considering critical scenarios of loading and generation may mask the impacts. One means of dealing with such complexity is through the use of indices that indicate the benefit or otherwise of connections at a given location and for a given horizon. This paper presents a multiobjective performance index for distribution networks with time-varying distributed generation which consider a number of technical issues. The approach has been applied to a medium voltage distribution network considering hourly demand and wind speeds. Results show that this proposal has a better response to the natural behavior of loads and generation than solely considering a single operation scenario

Evaluating distributed generation impacts with a multiobjective index

Evaluating the technical impacts associated with connecting distributed generation to distribution networks is a complex activity requiring a wide range of network operational and security effects to be qualified and quantified. One means of dealing with such complexity is through the use of indices that indicate the benefit or otherwise of connections at a given location and which could be used to shape the nature of the contract between the utility and distributed generator. This paper presents a multiobjective performance index for distribution networks with distributed generation which considers a wide range of technical issues. Distributed generation is extensively located and sized within the IEEE-34 test feeder, wherein the multiobjective performance index is computed for each configuration. The results are presented and discussed

Asymmetric superconductivity in metallic systems

Different types of superfluid ground states have been investigated in systems of two species of fermions with Fermi surfaces that do not match. This study is relevant for cold atomic systems, condensed matter physics and quark matter. In this paper we consider this problem in the case the fermionic quasi-particles can transmute into one another and only their total number is conserved. We use a BCS approximation to study superconductivity in two-band metallic systems with inter and intra-band interactions. Tuning the hybridization between the bands varies the mismatch of the Fermi surfaces and produces different instabilities. For inter-band attractive interactions we find a first order normal-superconductor and a homogeneous metastable phase with gapless excitations. In the case of intra-band interactions, the transition from the superconductor to the normal state as hybridization increases is continuous and associated with a quantum critical point. The case when both interactions are present is also considered.Comment: new enlarged version, new title, 7 pages, 7 figure

Analytical results for a Bessel function times Legendre polynomials class integrals

When treating problems of vector diffraction in electromagnetic theory, the evaluation of the integral involving Bessel and associated Legendre functions is necessary. Here we present the analytical result for this integral that will make unnecessary numerical quadrature techniques or localized approximations. The solution is presented using the properties of the Bessel and associated Legendre functions.Comment: 4 page

Uso de polímetro hidroretentor no plantio de cafeeiros em ambiente protegido.

A operação de plantio do cafeeiro em sequeiro é tradicionalmente executada na estação chuvosa, visando proporcionar condições satisfatórias de umidade para o desenvolvimento inicial das mudas no campo. Durante este período a distribuição das chuvas não é regular e a ocorrência de veranicos é freqüente, resultando em morte das plantas por falta de água. Realizou-se este trabalho com o objetivo de avaliar o efeito do polímero hidroretentor (hidrogel) sobre mudas de cafeeiros plantadas em vasos. A pesquisa foi conduzida em vasos, em casa de vegetação, na Fazenda Experimental da Fundação Procafé, Varginha, MG. O experimento consistiu em um fatorial com quatro doses do polímero (0,5; 1,0; 1,5 e 2,0 litros por vaso), dois modos de fornecimento de água e uma testemunha sem água. As mudas foram plantadas em vasos com os polímeros e estes pesados diariamente para monitoramento de perda de água durante 87dias, quando as plantas foram lavadas para medição das variáveis fenológicas. As liberações da água dos vasos para o meio foram maiores na presença do polímero até um período de trinta dias após o plantio, para as dosagens de 1,0 a 2,0 L/vaso do polímero hidratado. Houve aumento crescente na matéria seca das plantas a partir da dosagem de 1,0 L/vaso. Em casa de vegetação, o uso do polímero hidratado no plantio das mudas de café proporcionou maior desenvolvimento das plantas, sendo a melhor resposta obtida para dosagem de 2,0 L