RICARDO IGNACIO PEREIRA MARTINEZ | Universidad Cooperativa de Colombia (original) (raw)
Papers by RICARDO IGNACIO PEREIRA MARTINEZ
Claves De Razon Practica, 1999
Biblioteca de la Universidad Complutense de Madrid, Base de datos de artículos de revistas, ...
International Journal of Chemical Kinetics, 1983
Page 1. Methyl Thiirane: Kinetic Gas-Phase Titration of Sulfur Atoms in S,O, Systems RICHARD I. M... more Page 1. Methyl Thiirane: Kinetic Gas-Phase Titration of Sulfur Atoms in S,O, Systems RICHARD I. MARTINEZ* and JOHN T. HERRON National Burkau of Standards, Chemical Kinetics Division, Center for Chemical Physics, Washington, DC 20234 Abstract ...
This paper deals with the axiomatic derivation of social evaluation indices in a multidimensional... more This paper deals with the axiomatic derivation of social evaluation indices in a multidimensional context. The resulting evaluation formula is the geometric mean of the egalitarian equivalent values of the different characteristics under consideration. We provide an application to the measurement of human development and compare the results obtained with those corresponding to the standard (additive) index.
Agronomia Colombiana, Jun 14, 2011
Http Dx Doi Org 10 1080 00397910801997520, Jun 1, 2008
... Martínez-García a & Ricardo Martínez a * pages 1917-1925. ... Microwaves in Organic Synth... more ... Martínez-García a & Ricardo Martínez a * pages 1917-1925. ... Microwaves in Organic Synthesis ; Wiley-VCH : Weinheim , 2006 ; (b) Kappe , CO ; Stadler , A. Microwaves in Organic and Medicinal Chemistry ; Wiley-VCH : Weinhiem , 2005 ; (c) Lidström , P. ; Tierney , JP (Eds.). ...
This work presents the electrochemical results obtained during the study of the corrosion of X52 ... more This work presents the electrochemical results obtained during the study of the corrosion of X52 pipeline steel sample, immersed in brines containing H 2 S, under turbulent flow conditions. Linear polarisation resistance (LPR), electrochemical impedance spectroscopy (EIS), Electrochemical Noise (EN) and polarisation curves were used in order to determine the effect of turbulent flow upon the corrosion kinetics of the steel. It was found that flow has a considerable influence upon the electrochemical process occurring on the surface of the steel and the corrosion rate is increased.
Engineering Fracture Mechanics, Sep 1, 2010
Ductile iron (DI) is a family of cast alloys that covers a wide range of mechanical properties, d... more Ductile iron (DI) is a family of cast alloys that covers a wide range of mechanical properties, depending on its matrix microstructure. For instance, ferritic matrices used in parts, such as automotive suspension components, demand high impact properties and ductility among some of their main requirements. On the other hand, pearlitic and martensitic matrices are used when hardness, strength and wear resistance are of particular concern. When it comes to very high strength parts, ausferritic matrices, typically austempered ductile iron (ADI), are widely used.DI has been employed to replace cast and forged steels in a large number of applications and its production has shown a sustained rate of growth over the last decades.Knowing about failure modes and fracture mechanisms associated to materials with the properties mentioned above is crucial, since they can be of great value for designers of mechanical components.This paper deals with the analysis of fracture surfaces of ductile cast iron generated under different conditions of load application, temperature and environments.The studies include the examination of fracture surfaces obtained by means of tensile tests, impact tests and by samples used to determine fracture toughness properties, where the zones of fatigue pre-crack and monotonic load condition were evaluated. A special case of ductile iron fracture is also examined.The study of the different surfaces permitted to establish patterns that contributed to unveil the fracture mechanisms of ductile iron with different matrices, nodule count, etc.
Agronomia Colombiana, 2005
Van Dyke' mango fruits were harvested at physiological maturity and stored in active modified atm... more Van Dyke' mango fruits were harvested at physiological maturity and stored in active modified atmosphere conditions using different plastic packages (modified atmosphere packaging, MAP). Two-fruit-samples were placed in sealed caliber 2 and caliber 3 low density polyethylene packages (LDPE), using two initial atmosphere gas mixtures. Wrapped fruit and control fruit (without bagging) were kept at 12 °C and 90% relative humidity (RH) for 30 days plus 5 days' shelf life at 18 °C and 70% RH. Caliber 3 LDPE film ensured that injected O 2 concentration remained more stable and increased CO 2 content during storage time than caliber 2 film. MAP treatment increased fruit shelf-life by delaying the ripening process. MAP drastically reduced fruit weight loss and increased ascorbic acid content compared to control. Negative correlation was found between fruit weight loss and fruit ascorbic acid content and O 2 concentration within the plastic film and fruit ascorbic acid content. By contrast, there was direct correlation between CO 2 content within MAP and the ascorbic acid content of fruit. Mango fruit wrapped in caliber 2 PE film ensured the longest extension of the ripening period, without incurring fruit skin lesions. Fruit in caliber 3-PE-film failed to ripen due to flesh softening being inhibited and organic acid degradation.
In this work we deal with rationing problems. In particular with claims problems with indivisible... more In this work we deal with rationing problems. In particular with claims problems with indivisible goods, that is, problems in which a certain amount of indivisible units (of an homogeneous good), has to be distributed among a group of agents, when this amount is not enough to satisfy agents' demands. We use a subfamily of standards of comparisons (monotonic standards) to construct scheduling methods to solve this type of problems. The rules constructed in this way can be interpreted as discrete versions of the constrained equal awards and constrained equal losses rules when the good is perfectly divisible. They not only enjoy similar properties, but have stronger relations with the cea and cel rules in terms of expected values and the size of indivisibility.
Journal of Computational Methods in Sciences and Engineering, Apr 1, 2004
Methanol monohydrate is one of several crystalline phases present in the methanol-water system. A... more Methanol monohydrate is one of several crystalline phases present in the methanol-water system. At ambient conditions of pressure, methanol monohydrate has a polar disordered structure. Here we study its behavior under pressure using the density-functional theory in the ABINIT implementation. We propose several initial ideally ordered configurations that we optimize as a function of pressure. We characterize the compressibility and the relative stability of these different configurations under pressure. Two ideally ordered monoclinic structures with symmetry Cc and P21 are proposed as the most energetically favorable ones. Temperature-induced hydrogen disordering and reordering can easily turn them one into the other. We characterize a series of physical properties and their variation under pressure. We find a considerably large spontaneous polarization to occur which produces surface dipoles able to induce preferred overgrowth of other ices or clustering of other more complex polar organic molecules.
Molecular Diversity, 2010
A hydrogen autotransfer reaction has been applied to the α-alkylation of ketones, with primary al... more A hydrogen autotransfer reaction has been applied to the α-alkylation of ketones, with primary alcohols as the electrophilic component, either under homogeneous (using a Ru complex as catalyst) or under heterogeneous (using Ni nanoparticles) conditions. This process is both very efficient (concerning atom economy) and ecologically friendly (water as the only by-product generated). On the other hand, three multicomponent reactions, namely, the Strecker reaction (without any catalyst), the aza-Sakurai process (catalyzed by ferrite), and the addition of in situ generated Zn enolates to chiral sulfinylimines (catalyzed by Cu), have proven to be very efficient in the generation of a diversity of polyfunctionalized molecules.
Applied Economics Letters, 2012
Taking as a reference the new human development index introduced by the UN in 2010, we study ineq... more Taking as a reference the new human development index introduced by the UN in 2010, we study inequality in the world with respect to achievements in human development. We consider four of the most widely known measures of inequality: the Gini, Theil, Atkinson and Kolm indices. We analyse the evolution of each index over the whole history of UN human development reports (every 5 years, from 1980 to 2010). We find that according to the Gini, Theil and Atkinson measures, the world was significantly more equal in 2010 than in 1980. However, the Kolm index shows that the distribution of human development has worsened.
Working Papers, 2014
The top-two primary recently approved in states like Washington, California, and Alaska eliminate... more The top-two primary recently approved in states like Washington, California, and Alaska eliminates the closed party primaries and creates instead a single ballot in which the first and second place winners pass to the general election. We compare the electoral consequences of the top-two primary with those of the closed primaries. We present a model where each primary procedure induce a sequential game with three stages: candidate-entry stage, primary election, and general election. We analyze the equilibria of these games and show that the top-two primary contributes to political moderation and may increase the number of swing states.
The present investigation proposes that the nominalization index (the ratio of nouns to verbs in ... more The present investigation proposes that the nominalization index (the ratio of nouns to verbs in a given text) successfully predicts the academic-scientific character of a text. The results of a computer-assisted analysis of a 12.7 million word corpus show that this index is sensitive to the opposition between scientific/academic texts and letters to the editor/journalistic texts. It is likewise sensitive to the differences between applied sciences, natural sciences, social sciences and humanities texts, although there is a certain amount of overlap between these last two.
Claves De Razon Practica, 1999
Biblioteca de la Universidad Complutense de Madrid, Base de datos de artículos de revistas, ...
International Journal of Chemical Kinetics, 1983
Page 1. Methyl Thiirane: Kinetic Gas-Phase Titration of Sulfur Atoms in S,O, Systems RICHARD I. M... more Page 1. Methyl Thiirane: Kinetic Gas-Phase Titration of Sulfur Atoms in S,O, Systems RICHARD I. MARTINEZ* and JOHN T. HERRON National Burkau of Standards, Chemical Kinetics Division, Center for Chemical Physics, Washington, DC 20234 Abstract ...
This paper deals with the axiomatic derivation of social evaluation indices in a multidimensional... more This paper deals with the axiomatic derivation of social evaluation indices in a multidimensional context. The resulting evaluation formula is the geometric mean of the egalitarian equivalent values of the different characteristics under consideration. We provide an application to the measurement of human development and compare the results obtained with those corresponding to the standard (additive) index.
Agronomia Colombiana, Jun 14, 2011
Http Dx Doi Org 10 1080 00397910801997520, Jun 1, 2008
... Martínez-García a & Ricardo Martínez a * pages 1917-1925. ... Microwaves in Organic Synth... more ... Martínez-García a & Ricardo Martínez a * pages 1917-1925. ... Microwaves in Organic Synthesis ; Wiley-VCH : Weinheim , 2006 ; (b) Kappe , CO ; Stadler , A. Microwaves in Organic and Medicinal Chemistry ; Wiley-VCH : Weinhiem , 2005 ; (c) Lidström , P. ; Tierney , JP (Eds.). ...
This work presents the electrochemical results obtained during the study of the corrosion of X52 ... more This work presents the electrochemical results obtained during the study of the corrosion of X52 pipeline steel sample, immersed in brines containing H 2 S, under turbulent flow conditions. Linear polarisation resistance (LPR), electrochemical impedance spectroscopy (EIS), Electrochemical Noise (EN) and polarisation curves were used in order to determine the effect of turbulent flow upon the corrosion kinetics of the steel. It was found that flow has a considerable influence upon the electrochemical process occurring on the surface of the steel and the corrosion rate is increased.
Engineering Fracture Mechanics, Sep 1, 2010
Ductile iron (DI) is a family of cast alloys that covers a wide range of mechanical properties, d... more Ductile iron (DI) is a family of cast alloys that covers a wide range of mechanical properties, depending on its matrix microstructure. For instance, ferritic matrices used in parts, such as automotive suspension components, demand high impact properties and ductility among some of their main requirements. On the other hand, pearlitic and martensitic matrices are used when hardness, strength and wear resistance are of particular concern. When it comes to very high strength parts, ausferritic matrices, typically austempered ductile iron (ADI), are widely used.DI has been employed to replace cast and forged steels in a large number of applications and its production has shown a sustained rate of growth over the last decades.Knowing about failure modes and fracture mechanisms associated to materials with the properties mentioned above is crucial, since they can be of great value for designers of mechanical components.This paper deals with the analysis of fracture surfaces of ductile cast iron generated under different conditions of load application, temperature and environments.The studies include the examination of fracture surfaces obtained by means of tensile tests, impact tests and by samples used to determine fracture toughness properties, where the zones of fatigue pre-crack and monotonic load condition were evaluated. A special case of ductile iron fracture is also examined.The study of the different surfaces permitted to establish patterns that contributed to unveil the fracture mechanisms of ductile iron with different matrices, nodule count, etc.
Agronomia Colombiana, 2005
Van Dyke' mango fruits were harvested at physiological maturity and stored in active modified atm... more Van Dyke' mango fruits were harvested at physiological maturity and stored in active modified atmosphere conditions using different plastic packages (modified atmosphere packaging, MAP). Two-fruit-samples were placed in sealed caliber 2 and caliber 3 low density polyethylene packages (LDPE), using two initial atmosphere gas mixtures. Wrapped fruit and control fruit (without bagging) were kept at 12 °C and 90% relative humidity (RH) for 30 days plus 5 days' shelf life at 18 °C and 70% RH. Caliber 3 LDPE film ensured that injected O 2 concentration remained more stable and increased CO 2 content during storage time than caliber 2 film. MAP treatment increased fruit shelf-life by delaying the ripening process. MAP drastically reduced fruit weight loss and increased ascorbic acid content compared to control. Negative correlation was found between fruit weight loss and fruit ascorbic acid content and O 2 concentration within the plastic film and fruit ascorbic acid content. By contrast, there was direct correlation between CO 2 content within MAP and the ascorbic acid content of fruit. Mango fruit wrapped in caliber 2 PE film ensured the longest extension of the ripening period, without incurring fruit skin lesions. Fruit in caliber 3-PE-film failed to ripen due to flesh softening being inhibited and organic acid degradation.
In this work we deal with rationing problems. In particular with claims problems with indivisible... more In this work we deal with rationing problems. In particular with claims problems with indivisible goods, that is, problems in which a certain amount of indivisible units (of an homogeneous good), has to be distributed among a group of agents, when this amount is not enough to satisfy agents' demands. We use a subfamily of standards of comparisons (monotonic standards) to construct scheduling methods to solve this type of problems. The rules constructed in this way can be interpreted as discrete versions of the constrained equal awards and constrained equal losses rules when the good is perfectly divisible. They not only enjoy similar properties, but have stronger relations with the cea and cel rules in terms of expected values and the size of indivisibility.
Journal of Computational Methods in Sciences and Engineering, Apr 1, 2004
Methanol monohydrate is one of several crystalline phases present in the methanol-water system. A... more Methanol monohydrate is one of several crystalline phases present in the methanol-water system. At ambient conditions of pressure, methanol monohydrate has a polar disordered structure. Here we study its behavior under pressure using the density-functional theory in the ABINIT implementation. We propose several initial ideally ordered configurations that we optimize as a function of pressure. We characterize the compressibility and the relative stability of these different configurations under pressure. Two ideally ordered monoclinic structures with symmetry Cc and P21 are proposed as the most energetically favorable ones. Temperature-induced hydrogen disordering and reordering can easily turn them one into the other. We characterize a series of physical properties and their variation under pressure. We find a considerably large spontaneous polarization to occur which produces surface dipoles able to induce preferred overgrowth of other ices or clustering of other more complex polar organic molecules.
Molecular Diversity, 2010
A hydrogen autotransfer reaction has been applied to the α-alkylation of ketones, with primary al... more A hydrogen autotransfer reaction has been applied to the α-alkylation of ketones, with primary alcohols as the electrophilic component, either under homogeneous (using a Ru complex as catalyst) or under heterogeneous (using Ni nanoparticles) conditions. This process is both very efficient (concerning atom economy) and ecologically friendly (water as the only by-product generated). On the other hand, three multicomponent reactions, namely, the Strecker reaction (without any catalyst), the aza-Sakurai process (catalyzed by ferrite), and the addition of in situ generated Zn enolates to chiral sulfinylimines (catalyzed by Cu), have proven to be very efficient in the generation of a diversity of polyfunctionalized molecules.
Applied Economics Letters, 2012
Taking as a reference the new human development index introduced by the UN in 2010, we study ineq... more Taking as a reference the new human development index introduced by the UN in 2010, we study inequality in the world with respect to achievements in human development. We consider four of the most widely known measures of inequality: the Gini, Theil, Atkinson and Kolm indices. We analyse the evolution of each index over the whole history of UN human development reports (every 5 years, from 1980 to 2010). We find that according to the Gini, Theil and Atkinson measures, the world was significantly more equal in 2010 than in 1980. However, the Kolm index shows that the distribution of human development has worsened.
Working Papers, 2014
The top-two primary recently approved in states like Washington, California, and Alaska eliminate... more The top-two primary recently approved in states like Washington, California, and Alaska eliminates the closed party primaries and creates instead a single ballot in which the first and second place winners pass to the general election. We compare the electoral consequences of the top-two primary with those of the closed primaries. We present a model where each primary procedure induce a sequential game with three stages: candidate-entry stage, primary election, and general election. We analyze the equilibria of these games and show that the top-two primary contributes to political moderation and may increase the number of swing states.
The present investigation proposes that the nominalization index (the ratio of nouns to verbs in ... more The present investigation proposes that the nominalization index (the ratio of nouns to verbs in a given text) successfully predicts the academic-scientific character of a text. The results of a computer-assisted analysis of a 12.7 million word corpus show that this index is sensitive to the opposition between scientific/academic texts and letters to the editor/journalistic texts. It is likewise sensitive to the differences between applied sciences, natural sciences, social sciences and humanities texts, although there is a certain amount of overlap between these last two.