Multi-agent simulation of continental, regional, and micro electricity markets

Renewable based power generation has significantly increased over the last years. However, this process has evolved separately from electricity markets, leading to an inadequacy of the present market models to cope with huge quantities of renewable energy resources, and to take full advantage of the presently existing and the increasing envisaged renewable based and distributed energy resources. This paper proposes the modelling of electricity markets at several levels (continental, regional and micro), taking into account the specific characteristics of the players and resources involved in each level and ensuring that the proposed models accommodate adequate business models able to support the contribution of all the resources in the system, from the largest to the smaller ones. The proposed market models are integrated in MASCEM (Multi- Agent Simulator of Competitive Electricity Markets), using the multi agent approach advantages for overcoming the current inadequacy and significant limitations of the presently existing electricity market simulators to deal with the complex electricity market models that must be adopted.

Optimal scheduling of a renewable micro-grid in an isolated load area using mixed-integer linear programming

In the energy management of the isolated operation of small power system, the economic scheduling of the generation units is a crucial problem. Applying right timing can maximize the performance of the supply. The optimal operation of a wind turbine, a solar unit, a fuel cell and a storage battery is searched by a mixed-integer linear programming implemented in General Algebraic Modeling Systems (GAMS). A Virtual Power Producer (VPP) can optimal operate the generation units, assured the good functioning of equipment, including the maintenance, operation cost and the generation measurement and control. A central control at system allows a VPP to manage the optimal generation and their load control. The application of methodology to a real case study in Budapest Tech, demonstrates the effectiveness of this method to solve the optimal isolated dispatch of the DC micro-grid renewable energy park. The problem has been converged in 0.09 s and 30 iterations.

Self-mated tribological systems based on multilayer micro/nanocrystalline CVD diamond coatings

The tribological response of multilayer micro/nanocrystalline diamond coatings grown by the hot filament CVD technique is investigated. These multigrade systems were tailored to comprise a starting microcrystalline diamond (MCD) layer with high adhesion to a silicon nitride (Si3N4) ceramic substrate, and a top nanocrystalline diamond (NCD) layer with reduced surface roughness. Tribological tests were carried out with a reciprocating sliding configuration without lubrication. Such composite coatings exhibit a superior critical load before delamination (130���200 N), when compared to the mono- (60���100 N) and bilayer coatings (110 N), considering ���10 ��m thick films. Regarding the friction behaviour, a short-lived initial high friction coefficient was followed by low friction regimes (friction coefficients between 0.02 and 0.09) as a result of the polished surfaces tailored by the tribological solicitation. Very mild to mild wear regimes (wear coefficient values between 4.1��10���8 and 7.7��10���7 mm3 N���1 m���1) governed the wear performance of the self-mated multilayer coatings when subjected to high-load short-term tests (60���200 N; 2 h; 86 m) and medium-load endurance tests (60 N; 16 h; 691 m).

Role of abrasive material on micro-abrasion wear tests

Micro-abrasion wear tests with ball-cratering configuration are widely used. Sources of variability are already studied by different authors and conditions for testing are parameterized by BS EN 1071-6: 2007 standard which refers silicon carbide as abrasive. However, the use of other abrasives is possible and allowed. In this work, ball-cratering wear tests were performed using four different abrasive particles of three dissimilar materials: diamond, alumina and silicon carbide. Tests were carried out under the same conditions on a steel plate provided with TiB2 hard coating. For each abrasive, five different test durations were used allowing understanding the initial wear phenomena. Composition and shape of abrasive particles were investigated by SEM and EDS. Scar areas were observed by optical and electronic microscopy in order to understand the wear effects caused by each of them. Scar geometry and grooves were analyzed and compared. Wear coefficient was calculated for each situation. It was observed that diamond particles produce well-defined and circular wear scars. Different silicon carbide particles presented dissimilar results as consequence of distinct particle shape and size distribution.

Influence of the abrasive particles size in the micro-abrasion wear tests of TiAlSiN thin coatings

Ball rotating micro-abrasion tribometers are commonly used to carry out wear tests on thin hard coatings. In these tests, different kinds of abrasives were used, as alumina (Al2O3), silicon carbide (SiC) or diamond. In each kind of abrasive, several particle sizes can be used. Some studies were developed in order to evaluate the influence of the abrasive particle shape in the micro-abrasion process. Nevertheless, the particle size was not well correlated with the material removed amount and wear mechanisms. In this work, slurry of SiC abrasive in distilled water was used, with three different particles size. Initial surface topography was accessed by atomic force microscopy (AFM). Coating hardness measurements were performed with a micro-hardness tester. In order to evaluate the wear behaviour, a TiAlSiN thin hard film was used. The micro-abrasion tests were carried out with some different durations. The abrasive effect of the SiC particles was observed by scanning electron microscopy (SEM) both in the films (hard material) as in the substrate (soft material), after coating perforation. Wear grooves and removed material rate were compared and discussed.

Micro-abrasion wear behaviour of TiAlCrSiN nanostructured coatings

The injection process of glass fibres reinforced plastics promotes the moulds surface degradation by erosion. In order to improve its wear resistance, several kinds of PVD thin hard coatings were used. It is well-known that nanostructures present a better compromise between hardness and toughness. Indeed, when the coating is constituted by a large number of ultra-thin different layers, cracks and interface troubles tend to decrease. However, it is not clear that these nanostructures present a better wear behaviour in erosion processes. In order to study its wear behaviour, a sputtered PVD nanostructured TiAlCrSiN coating was used. The substrate and film surfaces topography were analyzed by profilometry and atomic force microscopy techniques. Film adhesion to the substrate was evaluated by scratch tests. The surface hardness was measured with a Vickers micro-hardness tester. The wear resistance was evaluated by micro-abrasion with a rotating ball tribometer tests. Slurry of SiC particles in distilled water was used in order to provoke the surface abrasion. Different duration tests were performed in order to analyze the wear evolution. After these tests, the wear mechanisms developed were analyzed by scanning electron microscopy. Wear craters were measured and the wear rate was calculated and discussed. With the same purpose, coated inserts were mounted in an injection mould working with a 30% glass fibres reinforced polypropylene. After 45 000 cycles no relevant wear was registered.

Business micro-location: factors, preferences and indicators to assess the influence factors

The paper presents a study on business micro-location behaviour as well as corresponding factors of in���uence, conducted in two metropolitan areas, Bucharest-Ilfov (Romania) and Greater Porto (Portugal). By business micro-location we refer to a speci���c site such as a building or facility, accommodating a business within a small, compact geographical area (e.g. metropolitan area). At this geographical scale, the macroeconomic layer factors were excluded, applicable when discern between regions or countries. The factors derived from location theory and previous empirical studies were surveyed, completing a cross-sectional analysis in order to ���nd out the speci���c weights of the location factors and preferences, by region and by industry. Based on already established ���rms��� feedback on location, the speci���c weights were granted by each industry to the main location factors, types of areas, and types of accommodation facilities. The authors also suggested a model to integrate these results into a Geographical Information System (GIS).

A constru����o da comunidade lus��fona apartir do antigo centro. Micro-comunidades e pr��ticas da lusofonia

Disserta����o apresentada para cumprimento dos requisitos necess��rios �� obten����o do grau de Doutor em Sociologia.

A import��ncia das consultoras no processo de internacionaliza����o das micro, pequenas e m��dias empresas em Portugal

Relat��rio de Est��gio Apresentado ao Instituto de Contabilidade e Administra����o do Porto para a obten����o do grau de Mestre em Empreendedorismo e Internacionaliza����o, sob orienta����o da Mestre In��s Veiga Pereira

Intelligent Micro Grid Management using a Multi-Agent approach

Recent changes in electricity markets (EMs) have been potentiating the globalization of distributed generation. With distributed generation the number of players acting in the EMs and connected to the main grid has grown, increasing the market complexity. Multi-agent simulation arises as an interesting way of analysing players��� behaviour and interactions, namely coalitions of players, as well as their effects on the market. MASCEM was developed to allow studying the market operation of several different players and MASGriP is being developed to allow the simulation of the micro and smart grid concepts in very different scenarios This paper presents a methodology based on artificial intelligence techniques (AI) for the management of a micro grid. The use of fuzzy logic is proposed for the analysis of the agent consumption elasticity, while a case based reasoning, used to predict agents��� reaction to price changes, is an interesting tool for the micro grid operator.

Two divergent ways to manage HR and to get to the top: an exploratory study in micro firms

Aim of the paper: The purpose of this paper is to examine human resources management practices (HRM practices) in small firms and to improve the understanding of the relationship between this kind of practices and business growth. This exploratory study is based on the resource-based view of the firm and empirical work carried out in two small firms by relating HRM practices with the firms��� results. Contribution to the literature: This is an in-depth study of HRM practices and its impact on performance growth in micro firms, isolating and controlling for most of the contextual and internal variables considered in the literature that relate HRM to growth. Firm growth analysis was broadened by the use of several dependent variables: employment growth and operational and financial performance growth. Some hypotheses for further research in identifying HRM practices in small business and its relation with firm growth are suggested. Methodology: Case study methodology was used to study two firms. The techniques used to collect data were semi-structured interviews to the owner and all the employees, unstructured observation at the firms��� facilities (during two days), entrepreneur profile definition (survey answer) and document data collection (on demographic characterization and performance results). Data was analyzed through content analysis methodology, and categories derived from the interviews��� protocols and literature. Results and implications: Results revealed that despite the firms��� organizational characteristics similarities, they differ significantly in owners��� motivation to grow, HRM practices and organizational performance and growth. Future studies should pay special attention to owner willingness to grow, to firms��� years of experience in business, to staff���s years of experience in their field of work and turnover. HRM practices in micro/small firms should be better defined and characterized. The external image of management posture relating to longitudinal financial results and growth should also be explored.

An organizational culture approach to performance in information technology micro-firms

This study aims to analyze and compare micro-firms��� organizational culture related to organizational performance. A case study methodology was used based on four firms, competitors among themselves in the Information Technology business, focusing on the years between 2008-2013. Findings pointed out many similarities to larger firms, but some specificities of micro-firms were found and propositions were defined: clan culture predominance is related to best performing micro-firms; the configuration of several culture types seemed to be the most suitable for obtaining good organizational results, provided that they do not focus only on hierarchy and market types of culture; the market culture predominance perception by employees is associated with low job satisfaction; and, after a certain time in business, micro-firms, as do larger companies, seek to standardize and control processes. Recognizing that organizational culture is considered important to firms��� results, this study sheds some light on that important factor for micro-firms.

Aquisi����o por Vis��o Artificial e Medi����o Autom��tica de Micro Dureza Vickers

O ensaio de dureza, e mais concretamente o ensaio de micro dureza Vickers, �� no universo dos ensaios mec��nicos um dos mais utilizados quer seja na ind��stria, no ensino ou na investiga����o e desenvolvimento de produto no ��mbito das ci��ncias dos materiais. Na grande maioria dos casos, a utiliza����o deste ensaio tem como principal aplica����o a caracteriza����o ou controlo da qualidade de fabrico de materiais met��licos. Sendo um ensaio de relativa simplicidade de execu����o, rapidez e com resultados compar��veis e relacion��veis a outras grandezas f��sicas das propriedades dos materiais. Contudo, e tratando-se de um m��todo de ensaio cuja interven����o humana �� importante, na medi����o da indenta����o gerada por penetra����o mec��nica atrav��s de um sistema ��tico, n��o deixa de exibir algumas debilidades que da�� adv��m, como sendo o treino dos t��cnicos e respetivas acuidades visuais, fen��menos de fadiga visual que afetam os resultados ao longo de um turno de trabalho; ora estes fen��menos afetam a repetibilidade e reprodutibilidade dos resultados obtidos no ensaio. O CINFU possui um micro dur��metro Vickers, cuja realiza����o dos ensaios depende de um t��cnico treinado para a execu����o do mesmo, apresentando todas as debilidades j�� mencionadas e que o tornou eleg��vel para o estudo e aplica����o de uma solu����o alternativa. Assim, esta disserta����o apresenta o desenvolvimento de uma solu����o alternativa ao m��todo ��tico convencional na medi����o de micro dureza Vickers. Utilizando programa����o em LabVIEW da National Instruments, juntamente com as ferramentas de vis��o computacional (NI Vision), o programa come��a por solicitar ao t��cnico a sele����o da c��mara para aquisi����o da imagem digital acoplada ao micro dur��metro, sele����o do m��todo de ensaio (For��a de ensaio); posteriormente o programa efetua o tratamento da imagem (aplica����o de filtros para elimina����o do ru��do de fundo da imagem original), segue-se, por indica����o do operador, a zona de interesse (ROI) e por sua vez s��o identificadas automaticamente os v��rtices da calote e respetivas dist��ncias das diagonais geradas concluindo, ap��s aceita����o das mesmas, com o respetivo c��lculo de micro dureza resultante. Para valida����o dos resultados foram utilizados blocos-padr��o de dureza certificada (CRM), cujos resultados foram satisfat��rios, tendo-se obtido um elevado n��vel de exatid��o nas medi����es efetuadas. Por fim, desenvolveu-se uma folha de c��lculo em Excel com a determina����o da incerteza associada ��s medi����es de micro dureza Vickers. Foram ent��o comparados os resultados nas duas metodologias poss��veis, pelo m��todo ��tico convencional e pela utiliza����o das ferramentas de vis��o computacional, tendo-se obtido bons resultados com a solu����o proposta.

Cellulose micro/nano fibers conformational effects probed by nematic liquid crystal droplets

Probing micro-/nano-sized surface conformations, which are ubiquitous in biological systems, by using liquid crystal droplets, which change their ordering and optical appearance in response to the presence of more than ten times smaller cellulose based micro/nano fibers, might find new uses in a range of biological environments and sensors. Previous studies indicate that electrospun micro/nano cellulosic fibers produced from liquid crystalline solutions could present a twisted form [1]. In this work, we study the structures of nematic liquid crystal droplets threaded by cellulose fibers prepared from liquid crystalline and isotropic solutions as well as droplets pierced by spider-made fibers [2]. Planar anchoring at the fibers and planar and homeotropic at the drop surfaces allowed probing cellulose fibers different helical structures as well as aligned filaments.