Scheduling distributed energy resources in an isolated grid - an artificial neural network approach

Power Systems (PS), have been affected by substantial penetration of Distributed Generation (DG) and the operation in competitive environments. The future PS will have to deal with large-scale integration of DG and other distributed energy resources (DER), such as storage means, and provide to market agents the means to ensure a flexible and secure operation. Virtual power players (VPP) can aggregate a diversity of players, namely generators and consumers, and a diversity of energy resources, including electricity generation based on several technologies, storage and demand response. This paper proposes an artificial neural network (ANN) based methodology to support VPP resource schedule. The trained network is able to achieve good schedule results requiring modest computational means. A real data test case is presented.

Energy resources management for more sustainable distribution systems: an intelligent approach

Energy Resources Management can play a very relevant role in future power systems in SmartGrid context, with high penetration of distributed generation and storage systems. This paper deals with the importance of resources management in incident situation. The system to consider a high penetration of distributed generation, demand response, storage units and network reconfiguration. A case study evidences the advantages of using a flexible SCADA to control the energy resources in incident situation.

Emergency energy resource management in SmartGrids

Energy resources management can play a very relevant role in future power systems in a SmartGrid context, with intensive penetration of distributed generation and storage systems. This paper deals with the importance of resource management in incident situations. The paper presents DemSi, an energy resources management simulator that has been developed by the authors to simulate electrical distribution networks with high distributed generation penetration, storage in network points and customers with demand response contracts. DemSi is used to undertake simulations for an incident scenario, evidencing the advantages of adequately using flexible contracts, storage, and reserve in order to limit incident consequences.

Demsi - a demand response simulator in the context of intensive use of distributed generation

Demand response can play a very relevant role in future power systems in which distributed generation can help to assure service continuity in some fault situations. This paper deals with the demand response concept and discusses its use in the context of competitive electricity markets and intensive use of distributed generation. The paper presents DemSi, a demand response simulator that allows studying demand response actions and schemes using a realistic network simulation based on PSCAD. Demand response opportunities are used in an optimized way considering flexible contracts between consumers and suppliers. A case study evidences the advantages of using flexible contracts and optimizing the available generation when there is a lack of supply.

Análise comparativa de soluções adotadas para a reabilitação de pavimentos flexíveis que integram a rede rodoviária nacional

A presente dissertação tem como objetivo efetuar a análise comparativa de soluções adotadas de reabilitação de pavimentos flexíveis que integram a rede rodoviária nacional. No âmbito desta análise apresenta-se o estado da arte respeitante à reabilitação de pavimentos flexíveis, nomeadamente: mecanismos de degradação, famílias de degradações, avaliação da capacidade de carga dos pavimentos, metodologia utilizada no dimensionamento do reforço de pavimentos, sendo também efetuada uma análise comparativa de técnicas de reforço de pavimentos e dos tratamentos antifendas. Neste contexto, apresenta-se um caso de estudo no qual é efetuada uma análise de três soluções possíveis para a reabilitação estrutural do pavimento do IC 20 entre Almada e a Costa de Caparica. É feita a descrição da solução projetada pela EP, SA patenteada em concurso público lançado em 2007, a qual é de certa forma inovadora ao nível do tratamento retardador da reflexão de fendas. Aquela solução técnica é constituída pela aplicação de grelhas de fibra de vidro e grelhas de fibra de carbono, seguidas da colocação de uma camada de desgaste em mistura betuminosa rugosa com betume modificado com baixa percentagem de borracha reciclada de pneus usados (BBr - BBB). Complementarmente, é efetuada a análise da solução do projeto de reabilitação do IC 20, patenteado pela Subconcessionária do Baixo Tejo, que contemplou a aplicação de misturas betuminosas rugosas com betume modificado com média percentagem de borracha reciclada de pneus usados (BBr - BBM). Para além da solução patenteada pela subconcessionária, é analisada a solução do projeto de alterações (variante) apresentado pelo agrupamento de empresas construtoras, que foi adotado na execução da obra realizada no IC 20. A intervenção de reabilitação estrutural contemplou a utilização de uma camada de ligação em AC 16 10/20 (MBAM) e uma camada de desgaste em mistura betuminosa rugosa com betume modificado com média percentagem de borracha reciclada de pneus usados (BBr - BBM). Adicionalmente à caracterização de diferentes soluções de reabilitação de pavimentos flexíveis adotados em Portugal, é efetuada uma análise comparativa dos custos de ciclo de vida (construção, manutenção e conservação) de cada tipo de solução de reabilitação.

Effect of the compact Ti layer on the efficiency of dye-sensitized solar cells assembled using stainless steel sheets

Titanium films have been deposited on stainless steel metal sheets using dc magnetron sputtering technique at different substrate temperatures. The structure of the titanium films strongly depend on the substrate temperature. The titanium film deposited at the substrate temperature lower than 300 ◦C has a loose flat sheet grains structure and the titanium film prepared at the substrate temperature higher than 500 ◦C has a dense nubby grains structure. The DSSC assembled using stainless steel sheet coated with titanium film deposited at high substrate temperature has a low charge transfer resistance in the TiO2/Ti interface and results in a high conversion efficiency. The DSSC assembled using stainless steel sheet coated with titanium film deposited at temperature higher than 500 ◦C has higher conversion efficiency than that assembled using titanium metal sheet as the substrate. The maximum conversion efficiency, 2.26% is obtained for DSSC assembled using stainless steel sheet coated with titanium film deposited at 700 ◦C substrate temperature, which is about 70% of the conversion efficiency of the FTO reference cell used in this study.

Relatório de estágio: POC para SNC

Mestrado em Contabilidade

Arrow Plot: a new graphical tool for selecting up and down regulated genes and genes differentially expressed on samples subgroups

Background: A common task in analyzing microarray data is to determine which genes are differentially expressed across two (or more) kind of tissue samples or samples submitted under experimental conditions. Several statistical methods have been proposed to accomplish this goal, generally based on measures of distance between classes. It is well known that biological samples are heterogeneous because of factors such as molecular subtypes or genetic background that are often unknown to the experimenter. For instance, in experiments which involve molecular classification of tumors it is important to identify significant subtypes of cancer. Bimodal or multimodal distributions often reflect the presence of subsamples mixtures. Consequently, there can be genes differentially expressed on sample subgroups which are missed if usual statistical approaches are used. In this paper we propose a new graphical tool which not only identifies genes with up and down regulations, but also genes with differential expression in different subclasses, that are usually missed if current statistical methods are used. This tool is based on two measures of distance between samples, namely the overlapping coefficient (OVL) between two densities and the area under the receiver operating characteristic (ROC) curve. The methodology proposed here was implemented in the open-source R software. Results: This method was applied to a publicly available dataset, as well as to a simulated dataset. We compared our results with the ones obtained using some of the standard methods for detecting differentially expressed genes, namely Welch t-statistic, fold change (FC), rank products (RP), average difference (AD), weighted average difference (WAD), moderated t-statistic (modT), intensity-based moderated t-statistic (ibmT), significance analysis of microarrays (samT) and area under the ROC curve (AUC). On both datasets all differentially expressed genes with bimodal or multimodal distributions were not selected by all standard selection procedures. We also compared our results with (i) area between ROC curve and rising area (ABCR) and (ii) the test for not proper ROC curves (TNRC). We found our methodology more comprehensive, because it detects both bimodal and multimodal distributions and different variances can be considered on both samples. Another advantage of our method is that we can analyze graphically the behavior of different kinds of differentially expressed genes. Conclusion: Our results indicate that the arrow plot represents a new flexible and useful tool for the analysis of gene expression profiles from microarrays.

Modeling Allee Effect from Beta(p, 2) Densities

In this work we develop and investigate generalized populational growth models, adjusted from Beta(p, 2) densities, with Allee effect. The use of a positive parameter leads the presented generalization, which yields some more flexible models with variable extinction rates. An Allee limit is incorporated so that the models under study have strong Allee effect.

Superefficiency and Multiplier Adjustment in Data Envelopment Analysis

Copyright © 2013 Springer Netherlands.

Multiplier adjustment in data envelopment analysis

V Congreso de Eficiencia y Productividad EFIUCO, Córdoba, 19-20 Mayo 2011.

Quais os atributos que um auditor interno deve ter

Dissertação apresentada ao Instituto Superior de Contabilidade para a obtenção do Grau de Mestre em Auditoria

Scalable Unified Transform Architecture for Advanced Video Coding Embedded Systems

A novel high throughput and scalable unified architecture for the computation of the transform operations in video codecs for advanced standards is presented in this paper. This structure can be used as a hardware accelerator in modern embedded systems to efficiently compute all the two-dimensional 4 x 4 and 2 x 2 transforms of the H.264/AVC standard. Moreover, its highly flexible design and hardware efficiency allows it to be easily scaled in terms of performance and hardware cost to meet the specific requirements of any given video coding application. Experimental results obtained using a Xilinx Virtex-5 FPGA demonstrated the superior performance and hardware efficiency levels provided by the proposed structure, which presents a throughput per unit of area relatively higher than other similar recently published designs targeting the H.264/AVC standard. Such results also showed that, when integrated in a multi-core embedded system, this architecture provides speedup factors of about 120x concerning pure software implementations of the transform algorithms, therefore allowing the computation, in real-time, of all the above mentioned transforms for Ultra High Definition Video (UHDV) sequences (4,320 x 7,680 @ 30 fps).

Desenvolvimento de uma ferramenta de pré-selecção de recursos para empresas ágeis/virtuais

Mestrado em Engenharia Electrotécnica e de Computadores

O papel da angiogênese e da hemólise na úlcera de perna de pessoas com anemia falciforme

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)