Short-Term Trading for a Wind-PV Power Producer in an Electricity Market

This paper deals with the problem of coordinated trading of wind and photovoltaic systems in order to find the optimal bid to submit in a pool-based electricity market. The coordination of wind and photovoltaic systems presents uncertainties not only due to electricity market prices, but also with wind and photovoltaic power forecast. Electricity markets are characterized by financial penalties in case of deficit or excess of generation. So, the aim o this work is to reduce these financial penalties and maximize the expected profit of the power producer. The problem is formulated as a stochastic linear programming problem. The proposed approach is validated with real data of pool-based electricity market of Iberian Peninsula.

A influência do modelo e estrutura de recursos humanos na motivação e comprometimento dos trabalhadores: gestão interna versus Outsourcing

Com esta investigação, pretende-se fazer uma análise comparativa sobre o comprometimento e motivação dos trabalhadores, tendo como fator diferencial a gestão do recrutamento, de modo interno e a gestão por outsourcing. O objetivo principal é verificar se existem diferenças significativas nos dois grupos de trabalhadores, à luz de um quadro teórico muito vasto. Para concretizar esta análise foi elaborado um questionário on-line, com questões de escala manifestadas por afirmações elaboradas, com base no enquadramento teórico que constituiu a revisão da literatura, sobre motivação e comprometimento. Os resultados demonstraram que não existem diferenças significativas nos valores médios dos dois grupos na avaliação dos fatores de motivação, embora em ambos os grupos, se verifique uma grande vontade de darem mais de si à organização, de forma a superarem objetivos. Os valores de motivação revelaram-se muito baixos no geral, nos dois grupos. Em ambos os grupos apurou-se que há mais insatisfação face a fatores recompensatórios (tanto a nível material como imaterial): o salário e o reconhecimento do trabalho. Em relação ao comprometimento, verifica-se menor comprometimento por parte dos trabalhadores outsourcing, não numa análise de comparabilidade de médias gerais, mas numa análise de médias mais específicas de alguns fatores em avaliação: intenções de abandono. As médias das intenções de abandono foram mais visíveis neste grupo. No geral, ambos os trabalhadores dos dois grupos são movidos por um comprometimento instrumental, mais relacionado com as poucas alternativas que o mercado de trabalho dispõe , para uma evolução profissional; Abstract: The influence of human resource management structure in the motivation and commitment of employees: internal management versus outsourcing With this research aims to make a comparative analysis on the commitment and motivation of workers, with the differentiating factor the management of the internal mode recruitment and management by outsourcing. The main objective is to verify whether there are significant differences in the two groups of workers in the light of a very broad theoretical framework. To realize this analysis was prepared an online questionnaire with scale issues raised by elaborate statements, based on the theoretical framework that was the literature review of motivation and commitment. The results showed no significant differences in mean values of the two groups in the evaluation of the motivating factors, although in both groups, that there is a great desire to give more of themselves to the organization in order to overcome objectives. The motivation values proved to be very low in general, in both groups. In both groups it was found that there is more dissatisfaction with the recompensatórios factors (both material and immaterial level): wages and recognition of the work. Regarding the commitment, there is less commitment by the outsourcing workers, not an analysis of comparability of overall averages but a more average specific analysis of some factors reviewed abandonment of intentions. The average dropout intentions were more visible in this group. Overall, both employees of the two groups are driven by an instrumental commitment, more related to the few alternatives that the labor market has for professional development.

A pointwise constrained version of the Liapunov convexity theorem for vectorial linear first-order control systems

We generalize the Liapunov convexity theorem's version for vectorial control systems driven by linear ODEs of first-order p = 1 , in any dimension d ∈ N , by including a pointwise state-constraint. More precisely, given a x ‾ ( ⋅ ) ∈ W p , 1 ( [ a , b ] , R d ) solving the convexified p-th order differential inclusion L p x ‾ ( t ) ∈ co { u 0 ( t ) , u 1 ( t ) , … , u m ( t ) } a.e., consider the general problem consisting in finding bang-bang solutions (i.e. L p x ˆ ( t ) ∈ { u 0 ( t ) , u 1 ( t ) , … , u m ( t ) } a.e.) under the same boundary-data, x ˆ ( k ) ( a ) = x ‾ ( k ) ( a ) & x ˆ ( k ) ( b ) = x ‾ ( k ) ( b ) ( k = 0 , 1 , … , p − 1 ); but restricted, moreover, by a pointwise state constraint of the type 〈 x ˆ ( t ) , ω 〉 ≤ 〈 x ‾ ( t ) , ω 〉 ∀ t ∈ [ a , b ] (e.g. ω = ( 1 , 0 , … , 0 ) yielding x ˆ 1 ( t ) ≤ x ‾ 1 ( t ) ). Previous results in the scalar d = 1 case were the pioneering Amar & Cellina paper (dealing with L p x ( ⋅ ) = x ′ ( ⋅ ) ), followed by Cerf & Mariconda results, who solved the general case of linear differential operators L p of order p ≥ 2 with C 0 ( [ a , b ] ) -coefficients. This paper is dedicated to: focus on the missing case p = 1 , i.e. using L p x ( ⋅ ) = x ′ ( ⋅ ) + A ( ⋅ ) x ( ⋅ ) ; generalize the dimension of x ( ⋅ ) , from the scalar case d = 1 to the vectorial d ∈ N case; weaken the coefficients, from continuous to integrable, so that A ( ⋅ ) now becomes a d × d -integrable matrix; and allow the directional vector ω to become a moving AC function ω ( ⋅ ) . Previous vectorial results had constant ω, no matrix (i.e. A ( ⋅ ) ≡ 0 ) and considered: constant control-vertices (Amar & Mariconda) and, more recently, integrable control-vertices (ourselves).