Recordações de Vandelli: Literatura e história nas viagens filosóficas de Portugal pelo Brasil

O confronto entre certas criações ficcionais e a dinâmica da colonização nos leva a diversos campos disciplinares. Se a história registrou o intenso intercâmbio de mercadorias e idéias que ocorreu entre Portugal e Brasil, a partir da descoberta do Novo Mundo, a literatura revisitou e recriou esse passado. É o que se constata na obra do escritor brasileiro João Guimarães Rosa, em que articulando a realidade e a imaginação, a natureza e o homem, o regional e o universal, o escritor de perfil naturalista ilumina a linguagem da História e da Ciência pela Arte. Com relação às expedições científicas portuguesas pelo Brasil, a história relata que, na segunda metade do século XVIII, Portugal impulsionou a elaboração de um projeto de confecção de uma História Natural, tendo como espaço de criação cultural a Academia Real das Ciências de Lisboa. Esse empreendimento, no entanto, não teria sido possìvel sem as ―viagens imaginárias‖ do intelectual Domenico Agostino Vandelli, correspondente de Lineu e um dos principais articuladores da política portuguesa dirigida às colônias. Assim, instruídos conforme o livro Viagens filosóficas ou dissertações sobre as importantes regras que o filósofo naturalista nas suas peregrinações deve principalmente observar, alunos da Universidade de Coimbra, onde Vandelli era professor de História Natural e Química, são preparados para explorar as colônias ultramarinas. Em meio à produção literária de Guimarães Rosa, destacamos o conto ―O recado do morro‖, do livro Corpo de baile, lançado em 1956, para um paralelo com a História. Nessa ficção, um narrador conta a estória de uma pitoresca expedição, formada por moradores de um vilarejo, contratados por um viajante alemão, que percorre o interior do estado de Minas Gerais. Região de grutas, minerais, vegetação de cerrado (com diversidade em espécies comestíveis e medicinais), de fazendas de gado, animais em perigo de extinção e homens sábios do sertão, é com o uso dessa enigmática paisagem, que o escritor vai moldar o seu ―recado‖. Através de um estudo comparado entre os ideais naturalistas de Vandelli (evidentes nas correspondências trocadas com Lineu e nas Instruções aos viajantes) e do escritor Guimarães Rosa (expresso de forma ficcional), destacamos a necessidade de se resgatar, nos dias atuais, seus trabalhos, como forma de se propor uma nova relação do homem com o meio ambiente. Nós, de fato, reconhecemos que Deus todo-poderoso escreveu dois livros, a natureza e a revelação [...] (Lineu, 1765) O confronto entre certas criações ficcionais e a dinâmica da colonização nos leva a percorrer interessantes caminhos da História, da Literatura e das Ciências da Natureza. Se a história registrou o intenso intercâmbio de produtos e idéias, que ocorreu entre Portugal e Brasil, via Atlântico, a partir da descoberta do Novo Mundo, alguns escritores do Modernismo brasileiro revisitaram e recriaram esse passado. No que se refere às expedições científicas portuguesas pelo Brasil, o historiador Oswaldo Munteal Filho lembra que, na segunda metade do século XVIII, Portugal impulsionou a elaboração de um projeto de confecção de uma História Natural de suas colônias, tendo como espaço de criação cultural e reflexiva a Academia Real das Ciências de Lisboa. Esse empreendimento, no entanto, não teria sido possìvel sem as ―viagens imaginárias‖ do intelectual ilustrado Domenico Agostino Vandelli, um dos principais articuladores da política portuguesa dirigida às colônias no âmbito da Academia. Segundo seu pensamento, era preciso munir os naturalistas com ferramentas capazes de desvendar um Brasil desconhecido do ponto de vista da ciência e ainda intocado quanto às potencialidades de seus elementos naturais. Portanto, o olhar do naturalista deveria passar, primeiro, pelo utilitário: as virtudes das plantas medicinais, os usos dos gêneros exóticos, o aproveitamento do reino animal e mineral e a fertilidade das extensas terras. Reordenar a Natureza, não mais de forma alegórica, mas através da observação e experiência figurava-lhe como medida necessária e urgente. A par disso e instruídos conforme o livro Viagens filosóficas ou dissertações sobre as importantes regras que o filósofo naturalista, nas suas peregrinações, deve principalmente observar, alunos da Universidade de Coimbra, onde Vandelli era professor de História Natural e Química, são preparados para explorar as colônias ultramarinas (p. 483-518).

Supporting real-time parallel task models with work-stealing

Dynamic parallel scheduling using work-stealing has gained popularity in academia and industry for its good performance, ease of implementation and theoretical bounds on space and time. Cores treat their own double-ended queues (deques) as a stack, pushing and popping threads from the bottom, but treat the deque of another randomly selected busy core as a queue, stealing threads only from the top, whenever they are idle. However, this standard approach cannot be directly applied to real-time systems, where the importance of parallelising tasks is increasing due to the limitations of multiprocessor scheduling theory regarding parallelism. Using one deque per core is obviously a source of priority inversion since high priority tasks may eventually be enqueued after lower priority tasks, possibly leading to deadline misses as in this case the lower priority tasks are the candidates when a stealing operation occurs. Our proposal is to replace the single non-priority deque of work-stealing with ordered per-processor priority deques of ready threads. The scheduling algorithm starts with a single deque per-core, but unlike traditional work-stealing, the total number of deques in the system may now exceed the number of processors. Instead of stealing randomly, cores steal from the highest priority deque.

O Conselho Europeu no Tratado de Lisboa: da margem dos tratados à crisálida intergovernamental

Temas de Integração - 1.º e 2.º Semestre de 2010 - N.º 29 e 30

A real time pricing approach to deal with excessive wind power situations

The introduction of wind power generation in several countries around the world, including in European countries, where energy policy directives have encouraged the use of renewables, led to several changes in market and power systems operation. The intensive integration of these sources has led to situations in which the demand is lower than the available renewable resources. In these situations a part of the available generation is wasted if not used for storage or to supply additional demand. This paper proposes a real time demand response methodology based on changing the electricity price for the consumers expecting an increase in the demand in the periods in which that demand is lower than the available renewable generation. The consumers response to the changes in electricity price is characterized by their price elasticity of demand considered distinct for each consumer type. The proposed methodology is applied to the Portuguese power system, in the context of the Iberian electricity market (MIBEL). The renewable-based producers are considered as special producers, with special tariffs, and so it is important to use the energy available as it will be paid anyway. In this context, consumers are entities actively participating in the operation of the market.

Real-time energy resources scheduling considering intensive wind penetration

The use of distributed energy resources, based on natural intermittent power sources, like wind generation, in power systems imposes the development of new adequate operation management and control methodologies. A short-term Energy Resource Management (ERM) methodology performed in two phases is proposed in this paper. The first one addresses the day-ahead ERM scheduling and the second one deals with the five-minute ahead ERM scheduling. The ERM scheduling is a complex optimization problem due to the high quantity of variables and constraints. In this paper the main goal is to minimize the operation costs from the point of view of a virtual power player that manages the network and the existing resources. The optimization problem is solved by a deterministic mixedinteger non-linear programming approach. A case study considering a distribution network with 33 bus, 66 distributed generation, 32 loads with demand response contracts and 7 storage units and 1000 electric vehicles has been implemented in a simulator developed in the field of the presented work, in order to validate the proposed short-term ERM methodology considering the dynamic power system behavior.

Energy resource scheduling in a real distribution network managed by several virtual power players

Smart Grids (SGs) appeared as the new paradigm for power system management and operation, being designed to integrate large amounts of distributed energy resources. This new paradigm requires a more efficient Energy Resource Management (ERM) and, simultaneously, makes this a more complex problem, due to the intensive use of distributed energy resources (DER), such as distributed generation, active consumers with demand response contracts, and storage units. This paper presents a methodology to address the energy resource scheduling, considering an intensive use of distributed generation and demand response contracts. A case study of a 30 kV real distribution network, including a substation with 6 feeders and 937 buses, is used to demonstrate the effectiveness of the proposed methodology. This network is managed by six virtual power players (VPP) with capability to manage the DER and the distribution network.

Adaptive tool for automatic data collection of real electricity markets

The study of electricity markets operation has been gaining an increasing importance in last years, as result of the new challenges that the electricity markets restructuring produced. This restructuring increased the competitiveness of the market, but with it its complexity. The growing complexity and unpredictability of the market’s evolution consequently increases the decision making difficulty. Therefore, the intervenient entities are forced to rethink their behaviour and market strategies. Currently, lots of information concerning electricity markets is available. These data, concerning innumerous regards of electricity markets operation, is accessible free of charge, and it is essential for understanding and suitably modelling electricity markets. This paper proposes a tool which is able to handle, store and dynamically update data. The development of the proposed tool is expected to be of great importance to improve the comprehension of electricity markets and the interactions among the involved entities.

Real-time energy resources scheduling considering short-term and very short-term wind forecast

This paper proposes an energy resources management methodology based on three distinct time horizons: day-ahead scheduling, hour-ahead scheduling, and real-time scheduling. In each scheduling process it is necessary the update of generation and consumption operation and of the storage and electric vehicles storage status. Besides the new operation condition, it is important more accurate forecast values of wind generation and of consumption using results of in short-term and very short-term methods. A case study considering a distribution network with intensive use of distributed generation and electric vehicles is presented.

Virtual power players dealing with excessive wind power situations using real time pricing

The increasing importance given by environmental policies to the dissemination and use of wind power has led to its fast and large integration in power systems. In most cases, this integration has been done in an intensive way, causing several impacts and challenges in current and future power systems operation and planning. One of these challenges is dealing with the system conditions in which the available wind power is higher than the system demand. This is one of the possible applications of demand response, which is a very promising resource in the context of competitive environments that integrates even more amounts of distributed energy resources, as well as new players. The methodology proposed aims the maximization of the social welfare in a smart grid operated by a virtual power player that manages the available energy resources. When facing excessive wind power generation availability, real time pricing is applied in order to induce the increase of consumption so that wind curtailment is minimized. The proposed method is especially useful when actual and day-ahead wind forecast differ significantly. The proposed method has been computationally implemented in GAMS optimization tool and its application is illustrated in this paper using a real 937-bus distribution network with 20310 consumers and 548 distributed generators, some of them with must take contracts.

Modelling real solar cell using PSCAD/MATLAB

This paper presents the development of a solar photovoltaic (PV) model based on PSCAD/EMTDC - Power System Computer Aided Design – including a mathematical model study. An additional algorithm has been implemented in MATLAB software in order to calculate several parameters required by the PSCAD developed model. All the simulation study has been performed in PSCAD/MATLAB software simulation tool. A real data base concerning irradiance, cell temperature and PV power generation was used in order to support the evaluation of the implemented PV model.

LMP triggered real time demand response events

Recent changes in power systems mainly due to the substantial increase of distributed generation and to the operation in competitive environments has created new challenges to operation and planning. In this context, 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. Demand response market implementation has been done in recent years. Several implementation models have been considered. An important characteristic of a demand response program is the trigger criterion. A program for which the event trigger depends on the Locational Marginal Price (LMP) used by the New England Independent System operator (ISO-NE) inspired the present paper. This paper proposes a methodology to support VPP demand response programs management. The proposed method has been computationally implemented and its application is illustrated using a 32 bus network with intensive use of distributed generation. Results concerning the evaluation of the impact of using demand response events are also presented.

Demand response in electrical energy supply: an optimal real time pricing approach

In competitive electricity markets with deep concerns for the efficiency level, demand response programs gain considerable significance. As demand response levels have decreased after the introduction of competition in the power industry, new approaches are required to take full advantage of demand response opportunities. This paper presents DemSi, a demand response simulator that allows studying demand response actions and schemes in distribution networks. It undertakes the technical validation of the solution using realistic network simulation based on PSCAD. The use of DemSi by a retailer in a situation of energy shortage, is presented. Load reduction is obtained using a consumer based price elasticity approach supported by real time pricing. Non-linear programming is used to maximize the retailer’s profit, determining the optimal solution for each envisaged load reduction. The solution determines the price variations considering two different approaches, price variations determined for each individual consumer or for each consumer type, allowing to prove that the approach used does not significantly influence the retailer’s profit. The paper presents a case study in a 33 bus distribution network with 5 distinct consumer types. The obtained results and conclusions show the adequacy of the used methodology and its importance for supporting retailers’ decision making.

Introduction to the special issue on real world applications of intelligent tutoring systems

The idea behind creating this special issue on real world applications of intelligent tutoring systems was to bring together in a single publication some of the most important examples of success in the use of ITS technology. This will serve as a reference to all researchers working in the area. It will also be an important resource for the industry, showing the maturity of ITS technology and creating an atmosphere for funding new ITS projects. Simultaneously, it will be valuable to academic groups, motivating students for new ideas of ITS and promoting new academic research work in the area.

Do papel dos meios de comunicação na vida em sociedade

Versão integral do artigo no link do editor

Para a história do ensino contabilistico de Lisboa e do porto no Portugal de oitocentos

Na segunda metade do século XIX foram fundados nas duas maiores cidades do país, Lisboa e Porto, nos anos de 1869 e 1886, respectivamente, dois estabelecimentos de ensino público de contabilidade: o Instituto Comercial de Lisboa e o Instituto Industrial e Comercial do Porto. ...