Controllability results for impulsive mixed type functional integro-differential evolution equations with nonlocal conditions

In this paper, we establish the controllability for a class of abstract impulsive mixed-type functional integro-differential equations with finite delay in a Banach space. Some sufficient conditions for controllability are obtained by using the Mönch fixed point theorem via measures of noncompactness and semigroup theory. Particularly, we do not assume the compactness of the evolution system. An example is given to illustrate the effectiveness of our results.

Demand response programs definition supported by clustering and classification techniques

The growing importance and influence of new resources connected to the power systems has caused many changes in their operation. Environmental policies and several well know advantages have been made renewable based energy resources largely disseminated. These resources, including Distributed Generation (DG), are being connected to lower voltage levels where Demand Response (DR) must be considered too. These changes increase the complexity of the system operation due to both new operational constraints and amounts of data to be processed. Virtual Power Players (VPP) are entities able to manage these resources. Addressing these issues, this paper proposes a methodology to support VPP actions when these act as a Curtailment Service Provider (CSP) that provides DR capacity to a DR program declared by the Independent System Operator (ISO) or by the VPP itself. The amount of DR capacity that the CSP can assure is determined using data mining techniques applied to a database which is obtained for a large set of operation scenarios. The paper includes a case study based on 27,000 scenarios considering a diversity of distributed resources in a 33 bus distribution network.

Mixed extractant systems for metal recovery

Hoje em dia, a prevenção dos resíduos de metais é uma questão muito importante para um grande número de empresas, pois necessitam optimizar o seu sistema de tratamento de águas residuais a fim de alcançarem os limites legais dos teores em iões metálicos e poderem efectuar a descarga das águas residuais no domínio hídrico público. Devido a esta problemática foram efectuados estudos inovadores relacionados com a remoção de iões metálicos de águas residuais, verificando-se que as tecnologias de membrana oferecem uma série de vantagens para o efeito. Uma dessas tecnologias, referida como Membrana Líquida de Suporte (SLM), é baseada num mecanismo de extracção. A membrana hidrofóbica, impregnada com uma solução extractora, funciona como barreira entre a água residual e uma solução, geralmente ácida. A diferença de pH entre a água residual e a solução actua como força motriz para o transporte de iões metálicos da água residual para a referida solução. Poderá ocorrer um problema de falta de estabilidade, resultante da possível fuga da solução extractora para fora dos poros das membranas. Estudos anteriores mostraram que os ácidos alquilfosfóricos ou ácidos fosfónicos, como os reagentes D2EHPA e CYANEX e hidroxioximas como o LIX 860-I podem ser muito úteis para a extração de iões metálicos como ferro, cobre, níquel, zinco e outros. A clássica extracção líquido-líquido também tem mostrado que a mistura de diferentes extractores pode ter um efeito sinergético. No entanto, não é claro que haja um efeito óptimo da razão de extractor ou que tipo de complexo é formado durante o processo de extracção. O objectivo deste projecto é investigar este comportamento sinergético e as complexas formações por meio de um método espectrofotométrico, o “Job’s method” e “Mole-ratio method”. Estes métodos são utilizados para estimar a estequiometria dos vários complexos entre dois solutos, a partir da variação de absorvância dos complexos quando comparado com a absorvância do soluto. Com este projecto, o Job’s method e mole-ratio method serão aplicados a um sistema de três componentes, para conseguir mais informações sobre a complexação de níquel (II) e a fim de determinar a razão extractor: metal dos complexos formados durante a aplicação de mistura de extractores D2EHPA e LIX 860-I. Segundo Job’s method a elavada absorvância situa-se na região de 0,015-0,040 M de LIX 860-I e uma baixa concentração de D2EHPA. Quando as diferentes experiências são encontradas num conjunto experimental foram avaliadas de acordo com o método de trabalho, o valor máximo do gráfico foi encontrado para uma baixa fração molar do ião metálico e uma maior concentração de D2EHPA. Esta mudança foi encontrado de 0,50 até 0,30, que poderia apontar para a direção da formação de diferentes complexos. Para o Mole-Ratio method, a estequiometria dos complexos metal pode ser determinada a partir do ponto de intersecção das linhas tangente do gráfico da absorbância versus a concentração do ligante. Em todos os casos, o máximo foi obtido em torno de uma concentração total de 0,010 M. Quando D2EHPA foi aplicado sozinho, absorvâncias muito baixos foram obtidas.

Economic, environmental and mixed objective functions in non-linear process optimization using simulated annealing and tabu search

Screening of topologies developed by hierarchical heuristic procedures can be carried out by comparing their optimal performance. In this work we will be exploiting mono-objective process optimization using two algorithms, simulated annealing and tabu search, and four different objective functions: two of the net present value type, one of them including environmental costs and two of the global potential impact type. The hydrodealkylation of toluene to produce benzene was used as case study, considering five topologies with different complexities mainly obtained by including or not liquid recycling and heat integration. The performance of the algorithms together with the objective functions was observed, analyzed and discussed from various perspectives: average deviation of results for each algorithm, capacity for producing high purity product, screening of topologies, objective functions robustness in screening of topologies, trade-offs between economic and environmental type objective functions and variability of optimum solutions.

Intake of milk, but not total dairy, yogurt, or cheese, is negatively associated with the clustering of cardiometabolic risk factors in adolescents

Epidemiologic studies have reported an inverse association between dairy product consumption and cardiometabolic risk factors in adults, but this relation is relatively unexplored in adolescents. We hypothesized that a higher dairy product intake is associated with lower cardiometabolic risk factor clustering in adolescents. To test this hypothesis, a cross-sectional study was conducted with 494 adolescents aged 15 to 18 years from the Azorean Archipelago, Portugal. We measured fasting glucose, insulin, total cholesterol, high-density lipoprotein cholesterol, triglycerides, systolic blood pressure, body fat, and cardiorespiratory fitness. We also calculated homeostatic model assessment and total cholesterol/high-density lipoprotein cholesterol ratio. For each one of these variables, a z score was computed using age and sex. A cardiometabolic risk score (CMRS) was constructed by summing up the z scores of all individual risk factors. High risk was considered to exist when an individual had at least 1 SD from this score. Diet was evaluated using a food frequency questionnaire, and the intake of total dairy (included milk, yogurt, and cheese), milk, yogurt, and cheese was categorized as low (equal to or below the median of the total sample) or “appropriate” (above the median of the total sample).The association between dairy product intake and CMRS was evaluated using separate logistic regression, and the results were adjusted for confounders. Adolescents with high milk intake had lower CMRS, compared with those with low intake (10.6% vs 18.1%, P = .018). Adolescents with appropriate milk intake were less likely to have high CMRS than those with low milk intake (odds ratio, 0.531; 95% confidence interval, 0.302-0.931). No association was found between CMRS and total dairy, yogurt, and cheese intake. Only milk intake seems to be inversely related to CMRS in adolescents.