Mario Pereira | Universidad Católica de Colombia (original) (raw)

Papers by Mario Pereira

Research paper thumbnail of A mixed integer disjunctive model for transmission network expansion

IEEE Transactions on Power Systems, 2001

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Research paper thumbnail of Transmission dispatch and congestion management in the emerging energy market structures

IEEE Transactions on Power Systems, 1998

... Perot Systems Corporation* University of Minnesota Electric POT\ er Research Institute* * Ele... more ... Perot Systems Corporation* University of Minnesota Electric POT\ er Research Institute* * Electricite de France Los Angeles, California Minneapolis, Minnesota Palo Alto, California Paris, France Mario Pereira Farrokh Rahimi Tom Schneider Brian Stott ...

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Research paper thumbnail of An Aumann-Shapley Approach to Allocate Transmission Service Cost Among Network Users in Electricity Markets

IEEE Transactions on Power Systems, 2007

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Research paper thumbnail of Auctions of contracts and energy call options to ensure supply adequacy in the second stage of the Brazilian power sector reform

Power Engineering Society, IEEE General Meeting, 2006

The reform process in the electricity sector of any country has as main objective the design of a... more The reform process in the electricity sector of any country has as main objective the design of a power market capable to induce a reliable and efficient energy supply, translated into adequate tariffs. Brazil started its reform process in 1996, inspired by similar schemes in the electricity sector of more developed countries. However, the existence of particularities in the country's hydroelectric energy market, such as weak spot price signals for system expansion and difficulties to determine benchmark prices, avoided a smooth transition to a fully deregulated market. In 2004, a revisited power sector model was launched, aiming at alleviating the difficulties of the first model. The core of the new proposals lies on the use of contract obligation and energy supply auctions as the backbone for the efficient contracting and supply adequacy. Supply auctions were held in 2004-2005, with a volume of about 20,000 average MW contracted involving about 60 billion USD in financial transactions. This work discusses the implementation of auctions of energy contracts and call options in Brazil as part of the mechanisms to ensure supply adequacy adopted in the second stage of its power sector reform

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Research paper thumbnail of Electricity and CO2 emissions system prices modeling and optimization

2009 IEEE Bucharest PowerTech, 2009

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Research paper thumbnail of Balance of power

IEEE Power & Energy Magazine, 2009

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Research paper thumbnail of Recent advances of sugarcane biomass cogeneration in Brazil

Power Engineering Society, IEEE General Meeting, 2009

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Research paper thumbnail of Diversity of freshwater algae

Aquatic ecology of the Mondego River basin global importance of local experience, 2002

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Research paper thumbnail of Allocation of Firm-Energy Rights among Hydro agents using Cooperative Game Theory: an Aumann-Shapley approach

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Research paper thumbnail of Complexity checking of ARM programs, by deduction

Proceedings of the 29th Annual ACM Symposium on Applied Computing - SAC '14, 2014

ABSTRACT In this paper we address two main questions: how to reason about the correctness of unst... more ABSTRACT In this paper we address two main questions: how to reason about the correctness of unstructured programs (particularly programs written in ARM Assembly) and how to use a proof-based system to check computational complexity of such programs. We approach the correctness issue by applying a flow sequentialization methodology and a formalized semantics of ARM instructions. An annotated ARM program is turned into a set of purely sequential programs, then each instruction is mapped into the corresponding formalized opcodes and finally Why3's VCGen is employed to generate proper Verification Conditions. Regarding complexity checking, we propose a methodology, based on the sequentialization process, by encoding instructions CPU-cost into their semantics and checking the program's calculated cost against user-supplied cost information (cost properties will be treated as normal functional annotations). Along with the formalization of correctness and complexity reasoning techniques, a prototype tool has been implemented and used to verify both the correctness and complexity of some practical examples.

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Research paper thumbnail of Supply adequacy in the Brazilian power market

Power Engineering Society, IEEE General Meeting, 2004

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Research paper thumbnail of Microcystin-producing blooms—a serious global public health issue

Ecotoxicology and Environmental Safety, 2004

The investigation on microcystin topics is increasing due to the related ecological and public he... more The investigation on microcystin topics is increasing due to the related ecological and public health risks. Recent investigation confirms a gap in establishing global patterns relating a particular environment to the bloom occurrence of a species and the production of certain microcystin variants. All the results concerning the environmental effects on the microcystin synthesis of one species must be checked in the light of genome diversity. Thus, the poisoning risks of a bloom depend on the strain causing toxicity. To be more effective, specific water treatment methods are required for blooms of different microcystin producing species (such as colonial and filamentous cyanobacteria found in stratified and unstratified water bodies, respectively). With the increasing number of new microcystin variants discovered, the development of new rapid, inexpensive and sensitive enough monitoring methods to promptly screen simultaneously a great diversity of toxins and also check their toxic effects is becoming necessary.

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Research paper thumbnail of Seasonal succession of cladocerans and phytoplankton and their interactions in a shallow eutrophic lake (Lake Vela, Portugal)

Acta Oncologica, 2006

Lake Vela is a polymictic shallow lake exhibiting some characteristics typical of an advanced tro... more Lake Vela is a polymictic shallow lake exhibiting some characteristics typical of an advanced trophic state, namely, the permanently turbid water, the reduction in biodiversity, and the recurrent occurrence of Cyanobacteria blooms, which occasionally lead to large fish kills. This study was carried out in order to understand the seasonal variation of Lake Vela’s phytoplankton and cladoceran communities and their interactions under advanced eutrophic conditions. When comparing our results with general models of plankton succession observed in other temperate and tropical lakes we found some coherence between several seasonal events. Our results suggest that phytoplankton is mainly regulated by nutrients (“bottom-up” effect). However, the warm mediterranean temperatures had an important role in the phytoplankton succession, being responsible for the rapid and intense Cyanobacteria development in spring and summer. Our work also demonstrated that phytoplankton is one of the main factors responsible for the seasonal structure of the community of cladocerans, which are well related to changes in algae diversity and abundance, being the Cyanobacteria having major impact. Moreover, the occurrence of a massive Cyanobacteria bloom during the study, which induced anoxia and consequent fish kill, enhanced the structuring role that fish have on the cladoceran seasonal succession and the effects of this episode in the normal seasonal succession of plankton.

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Research paper thumbnail of Effect of three different time periods of irrigation with EDTA-T, EDTA, and citric acid on smear layer removal

Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology, 2004

An in vitro study was conducted to evaluate the effect of EDTA-T, 17% EDTA, and 10% citric acid o... more An in vitro study was conducted to evaluate the effect of EDTA-T, 17% EDTA, and 10% citric acid on the removal of smear layer from root canal dentin after final irrigation for 3, 10, and 15 min.Root canals of 90 extracted human canines were divided into 9 groups of 10 teeth; each group received a final irrigation with one of the irrigants for the established time intervals. After irrigation, the teeth were split and prepared for SEM analysis to determine the number of open dentinal tubules.There were statistically significant better results (P < .05) when irrigation with 10% citric acid for 3 min was compared to 10 and 15 min, and when irrigation with EDTA for 3 min was compared to 15 min. In all cases, irrigation for 3 min presented the greatest number of open dentinal tubules. There were no significant differences (P > .05) for the 3 time intervals of irrigation for EDTA-T, although there were a greater number of open tubules at 3 min.These 3 irrigants were effective at the shortest time tested and did not demonstrate an improved effect with an increase in time.

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Research paper thumbnail of The effect of environmental parameters and cyanobacterial blooms on phytoplankton dynamics of a Portuguese temperate Lake

Hydrobiologia, 2006

The increasing occurrence of cyanobacterial blooms in freshwaters is of great concern due to the ... more The increasing occurrence of cyanobacterial blooms in freshwaters is of great concern due to the ability of many cyanobacteria to produce cyanotoxins. In the present work, the eutrophied Vela Lake (Central Portugal), used for recreational purposes and as a water source for agriculture, was monitored every fortnight between 2000 and 2001. Phytoplankton diversity and densities were measured and correlated to environmental parameters. A seasonal phytoplanktonic succession was observed and it was mainly correlated with conductivity, temperature, total suspended solids and nutrients availability (particularly phosphorus). Diatoms were dominant during winter months (inferior temperatures and higher nutrients availability) followed by green algae in early spring and then cyanobacteria from late spring until early autumn (less nutrient availability and higher temperatures). A massive cyanobacterial bloom of Aphanizomenon flos-aquae occurred early in May 2001 and was preceded by the lowest nitrogen levels measured in the water during all the study period. At the time of this bloom senescence, dissolved oxygen was severely depleted and a massive death of ichthyofauna was recorded. A Microcystis aeruginosa bloom was also detected in July 2001 and it occurred following a rapid decrease in abundance of green algae and diatoms. By considering not only the environmental parameters but also the occurrence of cyanobacterial blooms as explanatory variables in a canonical correspondence analysis, the variance explained for the phytoplanktonic assemblage during the study period was increased in about 7% achieving a total of 61.0%, indicating a correlation that may be due to the known competitive advantage and/or allelopathy of the bloom-forming cyanobacteria towards microalgae.

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Research paper thumbnail of Diatom ecological preferences in a shallow temperate estuary (Ria de Aveiro, Western Portugal)

Hydrobiologia, 2005

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Research paper thumbnail of Acetylsalicylic acid and morphology of red blood cells

Brazilian Archives of Biology and Technology, 2010

... Jacques Natan Grinapel Frydman I,II ; Adenilson de Souza da Fonseca II, * ; Vanessa Câmara da... more ... Jacques Natan Grinapel Frydman I,II ; Adenilson de Souza da Fonseca II, * ; Vanessa Câmara da Rocha II ; Monica Oliveira Benarroz I,II ; Gabrielle ... the alterations induced by natural products and synthetic drugs on membrane of red blood cells (Oliveira et al., 2002; Moreno et al ...

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Research paper thumbnail of Structure, organization and elemental composition of the envelopes of Trachelomonas (Euglenophyta): a review

Acta Oecologica, 2003

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Research paper thumbnail of Ecological notes on the species of Phacus Dujardin (Euglenophyta) from the central region of Portugal

Acta Oecologica, 2003

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Research paper thumbnail of Inorganic composition of the envelopes of Trachelomonas Ehr. (Euglenophyta)

Acta Oecologica, 2003

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Research paper thumbnail of A mixed integer disjunctive model for transmission network expansion

IEEE Transactions on Power Systems, 2001

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Research paper thumbnail of Transmission dispatch and congestion management in the emerging energy market structures

IEEE Transactions on Power Systems, 1998

... Perot Systems Corporation* University of Minnesota Electric POT\ er Research Institute* * Ele... more ... Perot Systems Corporation* University of Minnesota Electric POT\ er Research Institute* * Electricite de France Los Angeles, California Minneapolis, Minnesota Palo Alto, California Paris, France Mario Pereira Farrokh Rahimi Tom Schneider Brian Stott ...

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Research paper thumbnail of An Aumann-Shapley Approach to Allocate Transmission Service Cost Among Network Users in Electricity Markets

IEEE Transactions on Power Systems, 2007

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Research paper thumbnail of Auctions of contracts and energy call options to ensure supply adequacy in the second stage of the Brazilian power sector reform

Power Engineering Society, IEEE General Meeting, 2006

The reform process in the electricity sector of any country has as main objective the design of a... more The reform process in the electricity sector of any country has as main objective the design of a power market capable to induce a reliable and efficient energy supply, translated into adequate tariffs. Brazil started its reform process in 1996, inspired by similar schemes in the electricity sector of more developed countries. However, the existence of particularities in the country's hydroelectric energy market, such as weak spot price signals for system expansion and difficulties to determine benchmark prices, avoided a smooth transition to a fully deregulated market. In 2004, a revisited power sector model was launched, aiming at alleviating the difficulties of the first model. The core of the new proposals lies on the use of contract obligation and energy supply auctions as the backbone for the efficient contracting and supply adequacy. Supply auctions were held in 2004-2005, with a volume of about 20,000 average MW contracted involving about 60 billion USD in financial transactions. This work discusses the implementation of auctions of energy contracts and call options in Brazil as part of the mechanisms to ensure supply adequacy adopted in the second stage of its power sector reform

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Electricity and CO2 emissions system prices modeling and optimization

2009 IEEE Bucharest PowerTech, 2009

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Research paper thumbnail of Balance of power

IEEE Power & Energy Magazine, 2009

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Recent advances of sugarcane biomass cogeneration in Brazil

Power Engineering Society, IEEE General Meeting, 2009

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Diversity of freshwater algae

Aquatic ecology of the Mondego River basin global importance of local experience, 2002

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Allocation of Firm-Energy Rights among Hydro agents using Cooperative Game Theory: an Aumann-Shapley approach

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Complexity checking of ARM programs, by deduction

Proceedings of the 29th Annual ACM Symposium on Applied Computing - SAC '14, 2014

ABSTRACT In this paper we address two main questions: how to reason about the correctness of unst... more ABSTRACT In this paper we address two main questions: how to reason about the correctness of unstructured programs (particularly programs written in ARM Assembly) and how to use a proof-based system to check computational complexity of such programs. We approach the correctness issue by applying a flow sequentialization methodology and a formalized semantics of ARM instructions. An annotated ARM program is turned into a set of purely sequential programs, then each instruction is mapped into the corresponding formalized opcodes and finally Why3&#39;s VCGen is employed to generate proper Verification Conditions. Regarding complexity checking, we propose a methodology, based on the sequentialization process, by encoding instructions CPU-cost into their semantics and checking the program&#39;s calculated cost against user-supplied cost information (cost properties will be treated as normal functional annotations). Along with the formalization of correctness and complexity reasoning techniques, a prototype tool has been implemented and used to verify both the correctness and complexity of some practical examples.

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Research paper thumbnail of Supply adequacy in the Brazilian power market

Power Engineering Society, IEEE General Meeting, 2004

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Research paper thumbnail of Microcystin-producing blooms—a serious global public health issue

Ecotoxicology and Environmental Safety, 2004

The investigation on microcystin topics is increasing due to the related ecological and public he... more The investigation on microcystin topics is increasing due to the related ecological and public health risks. Recent investigation confirms a gap in establishing global patterns relating a particular environment to the bloom occurrence of a species and the production of certain microcystin variants. All the results concerning the environmental effects on the microcystin synthesis of one species must be checked in the light of genome diversity. Thus, the poisoning risks of a bloom depend on the strain causing toxicity. To be more effective, specific water treatment methods are required for blooms of different microcystin producing species (such as colonial and filamentous cyanobacteria found in stratified and unstratified water bodies, respectively). With the increasing number of new microcystin variants discovered, the development of new rapid, inexpensive and sensitive enough monitoring methods to promptly screen simultaneously a great diversity of toxins and also check their toxic effects is becoming necessary.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Seasonal succession of cladocerans and phytoplankton and their interactions in a shallow eutrophic lake (Lake Vela, Portugal)

Acta Oncologica, 2006

Lake Vela is a polymictic shallow lake exhibiting some characteristics typical of an advanced tro... more Lake Vela is a polymictic shallow lake exhibiting some characteristics typical of an advanced trophic state, namely, the permanently turbid water, the reduction in biodiversity, and the recurrent occurrence of Cyanobacteria blooms, which occasionally lead to large fish kills. This study was carried out in order to understand the seasonal variation of Lake Vela’s phytoplankton and cladoceran communities and their interactions under advanced eutrophic conditions. When comparing our results with general models of plankton succession observed in other temperate and tropical lakes we found some coherence between several seasonal events. Our results suggest that phytoplankton is mainly regulated by nutrients (“bottom-up” effect). However, the warm mediterranean temperatures had an important role in the phytoplankton succession, being responsible for the rapid and intense Cyanobacteria development in spring and summer. Our work also demonstrated that phytoplankton is one of the main factors responsible for the seasonal structure of the community of cladocerans, which are well related to changes in algae diversity and abundance, being the Cyanobacteria having major impact. Moreover, the occurrence of a massive Cyanobacteria bloom during the study, which induced anoxia and consequent fish kill, enhanced the structuring role that fish have on the cladoceran seasonal succession and the effects of this episode in the normal seasonal succession of plankton.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effect of three different time periods of irrigation with EDTA-T, EDTA, and citric acid on smear layer removal

Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology, 2004

An in vitro study was conducted to evaluate the effect of EDTA-T, 17% EDTA, and 10% citric acid o... more An in vitro study was conducted to evaluate the effect of EDTA-T, 17% EDTA, and 10% citric acid on the removal of smear layer from root canal dentin after final irrigation for 3, 10, and 15 min.Root canals of 90 extracted human canines were divided into 9 groups of 10 teeth; each group received a final irrigation with one of the irrigants for the established time intervals. After irrigation, the teeth were split and prepared for SEM analysis to determine the number of open dentinal tubules.There were statistically significant better results (P < .05) when irrigation with 10% citric acid for 3 min was compared to 10 and 15 min, and when irrigation with EDTA for 3 min was compared to 15 min. In all cases, irrigation for 3 min presented the greatest number of open dentinal tubules. There were no significant differences (P > .05) for the 3 time intervals of irrigation for EDTA-T, although there were a greater number of open tubules at 3 min.These 3 irrigants were effective at the shortest time tested and did not demonstrate an improved effect with an increase in time.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The effect of environmental parameters and cyanobacterial blooms on phytoplankton dynamics of a Portuguese temperate Lake

Hydrobiologia, 2006

The increasing occurrence of cyanobacterial blooms in freshwaters is of great concern due to the ... more The increasing occurrence of cyanobacterial blooms in freshwaters is of great concern due to the ability of many cyanobacteria to produce cyanotoxins. In the present work, the eutrophied Vela Lake (Central Portugal), used for recreational purposes and as a water source for agriculture, was monitored every fortnight between 2000 and 2001. Phytoplankton diversity and densities were measured and correlated to environmental parameters. A seasonal phytoplanktonic succession was observed and it was mainly correlated with conductivity, temperature, total suspended solids and nutrients availability (particularly phosphorus). Diatoms were dominant during winter months (inferior temperatures and higher nutrients availability) followed by green algae in early spring and then cyanobacteria from late spring until early autumn (less nutrient availability and higher temperatures). A massive cyanobacterial bloom of Aphanizomenon flos-aquae occurred early in May 2001 and was preceded by the lowest nitrogen levels measured in the water during all the study period. At the time of this bloom senescence, dissolved oxygen was severely depleted and a massive death of ichthyofauna was recorded. A Microcystis aeruginosa bloom was also detected in July 2001 and it occurred following a rapid decrease in abundance of green algae and diatoms. By considering not only the environmental parameters but also the occurrence of cyanobacterial blooms as explanatory variables in a canonical correspondence analysis, the variance explained for the phytoplanktonic assemblage during the study period was increased in about 7% achieving a total of 61.0%, indicating a correlation that may be due to the known competitive advantage and/or allelopathy of the bloom-forming cyanobacteria towards microalgae.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Diatom ecological preferences in a shallow temperate estuary (Ria de Aveiro, Western Portugal)

Hydrobiologia, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Acetylsalicylic acid and morphology of red blood cells

Brazilian Archives of Biology and Technology, 2010

... Jacques Natan Grinapel Frydman I,II ; Adenilson de Souza da Fonseca II, * ; Vanessa Câmara da... more ... Jacques Natan Grinapel Frydman I,II ; Adenilson de Souza da Fonseca II, * ; Vanessa Câmara da Rocha II ; Monica Oliveira Benarroz I,II ; Gabrielle ... the alterations induced by natural products and synthetic drugs on membrane of red blood cells (Oliveira et al., 2002; Moreno et al ...

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Research paper thumbnail of Structure, organization and elemental composition of the envelopes of Trachelomonas (Euglenophyta): a review

Acta Oecologica, 2003

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Research paper thumbnail of Ecological notes on the species of Phacus Dujardin (Euglenophyta) from the central region of Portugal

Acta Oecologica, 2003

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Inorganic composition of the envelopes of Trachelomonas Ehr. (Euglenophyta)

Acta Oecologica, 2003

Bookmarks Related papers MentionsView impact