Jose Ignacio Gregorio Santos - Profile on Academia.edu (original) (raw)
Papers by Jose Ignacio Gregorio Santos
Biped locomotion control with evolved adaptive center-crossing continuous time recurrent neural networks
Neurocomputing, 2012
ABSTRACT We used center-crossing continuous time recurrent neural networks as central pattern gen... more ABSTRACT We used center-crossing continuous time recurrent neural networks as central pattern generator controllers in biped robots, together with an adaptive methodology to improve the ability of the recurrent neural networks to produce rhythmic activation behaviors. The parameters of the recurrent networks are adapted or modified in run-time to reach the center-crossing condition, so the nodes get close to the most sensitive region to their input. This facilitates the evolution of the networks that act as central pattern generators to control biped structures. The robustness of the adaptive networks to produce rhythmic activation patterns was checked as well as the improvements and possibilities this adaptation may add.
Implementation of a least-squares multi-harmonic fitting algorithm in the multicore cell processor
2012 IEEE I2MTC - International Instrumentation and Measurement Technology Conference, Proceedings, 2012
Least squares (LS) methods minimize the LS error between a specific data model and an acquired da... more Least squares (LS) methods minimize the LS error between a specific data model and an acquired data set. This is the case of sine-fitting algorithms, which are used to determine the sine wave parameters that best fit an acquired signal. In the case of signals with multiple harmonics, one can use a multi-harmonic fitting algorithm resembling the sine-fitting algorithm to estimate the amplitudes and phases of the harmonics. This paper describes the implementation of a LS multi-harmonic fitting algorithm using the multicore Cell processor to determine the fundamental frequency of a multi-harmonic signal and then the harmonic amplitudes and phases.
Pyrothiocarbonates I. Aminolysis of S-(Ethoxycarbonyl) O-Ethyl Dithiocarbonate
Phosphorus and Sulfur and the Related Elements, 1983
Abstract The reaction of S-(ethoxycarbonyl) O-ethyl dithiocarbonate (1) with equimolar amounts of... more Abstract The reaction of S-(ethoxycarbonyl) O-ethyl dithiocarbonate (1) with equimolar amounts of butylamine, benzylamine, diethylamine and piperidine in ethanol solution at 0° C is reported. The mole ratio of O-ethyl thiocarbamate (2) and O-ethyl carbamate (3) formed ...
Pyrothiocarbonates. Part 2. Reaction of S-ethoxycarbonyl O-ethyl dithiocarbonate with some potassium O-alkylthiocarbonates
Journal of the Chemical Society, Perkin Transactions 1, 1983
ABSTRACT
Thermal Modeling of In-Depth Thermocouple Response in Ablative Heat Shield Materials
26th AIAA Aerodynamic Measurement Technology and Ground Testing Conference, 2008
Page 1. Thermal Modeling of In-Depth Thermocouple Response in Ablative TPS Materials Thermal &... more Page 1. Thermal Modeling of In-Depth Thermocouple Response in Ablative TPS Materials Thermal & Fluids Analysis Workshop (TFAWS 2008) San Jose State University, San Jose, CA August 18, 2008 Jose A. Santos Robin A. Beck Timothy K. Risch Sierra Lobo, Inc. ...
Kinetic study on the aromatic nucleophilic substitution reaction of 3,6-dichloro-1,2,4,5-tetrazine by biothiols
Journal of Physical Organic Chemistry, 2014
ABSTRACT The aromatic nucleophilic substitution reaction of 3,6‐dichloro‐1,2,4,5‐tetrazine (DCT) ... more ABSTRACT The aromatic nucleophilic substitution reaction of 3,6‐dichloro‐1,2,4,5‐tetrazine (DCT) with a series of biothiols RSH: (cysteine, homocysteine, cysteinyl–glycine, N‐acetylcysteine, and glutathione) is subjected to a kinetic investigation. The reactions are studied by following spectrophotometrically the disappearance of DCT at 370 nm. In the case of an excess of N‐acetylcysteine and glutathione, clean pseudo first‐order rate constants (k obs1) are found. However, for cysteine, homocysteine and cysteinyl–glycine, two consecutive reactions are observed. The first one is the nucleophilic aromatic substitution of the chlorine by the sulfhydryl group of these biothiols (RSH) and the second one is the intramolecular and intermolecularnucleophilic aromatic substitutions of their alkylthio with the amine group of RSH to give the di‐substituted compound. Therefore, in these cases, two pseudo first‐order rate constants (k obs1 and k obs2, respectively) are found under biothiol excess. Plots of k obs1 versus free thiol concentration at constant pH are linear, with the slope (k N) independent of pH (from 6.8 to 7.4). The kinetic data analysis (Brønsted‐type plot and activation parameters) is consistent with an addition–elimination mechanism with the nucleophilic attack as the rate‐determining step. Copyright © 2014 John Wiley & Sons, Ltd. The title reaction is subjected to a kinetic investigation. We propose a bimolecular reaction type: addition–elimination (SNAr) for the nucleophilic attack of the series of thiols to tetrazine, in which the formation of the Meisenheimer complex is the rate‐determining step of the reaction. Subsequently, in some cases, a second intramolecular and intermolecular nucleophilic aromatic substitution of alkylthio with the amino group was evidenced.
Tetrahedron, 2006
The pyridinolysis of S-methyl chlorothioformate shows a biphasic Brønsted-type plot, in agreement... more The pyridinolysis of S-methyl chlorothioformate shows a biphasic Brønsted-type plot, in agreement with a stepwise mechanism and a change in the rate-limiting step, from formation of a zwitterionic tetrahedral intermediate (T AE ) at high pK a to its breakdown at low pK a . The reaction of the same substrate with secondary alicyclic amines shows a linear Brønsted-type plot of slope 0.23, which is in accordance with a stepwise mechanism where formation of T AE is the rate-determining step for the whole pK a range examined.
Protein folding with cellular automata in the 3D HP model
Proceeding of the fifteenth annual conference companion on Genetic and evolutionary computation conference companion - GECCO '13 Companion, 2013
ABSTRACT In the difficult ab initio prediction in protein folding only the information of the pri... more ABSTRACT In the difficult ab initio prediction in protein folding only the information of the primary structure of amino acids is used to determine the final folded conformation. The complexity of the interactions and the nature of the amino acid elements are reduced with the use of lattice models like HP, which categorizes the amino acids regarding their hydrophobicity. On the contrary to the intense research performed on the direct prediction of the final folded conformation, our aim here is to model the dynamic and emergent folding process through time, using the scheme of cellular automata but implemented with artificial neural networks optimized with Differential Evolution. Moreover, as the iterative folding also provides the final folded conformation, we can compare the results with those from direct prediction methods of the final protein conformation.
Cellular automata for modeling protein folding using the HP model
2013 IEEE Congress on Evolutionary Computation, 2013
ABSTRACT We used cellular automata (CA) for the modeling of the temporal folding of proteins. Unl... more ABSTRACT We used cellular automata (CA) for the modeling of the temporal folding of proteins. Unlike the focus of the vast research already done on the direct prediction of the final folded conformations, we will model the temporal and dynamic folding process. The CA model defines how the amino acids interact through time to obtain a folded conformation. We employed the TIP model to represent the protein conformations in a lattice, we extended the classical CA models using artificial neural networks for their implementation, and we used evolutionary computing to automatically obtain the models by means of Differential Evolution. Moreover, the modeling of the folding provides the final protein conformation.
Arc Jet Testing in a Shear Environment for Mars Science Laboratory Thermal Protection System
41st AIAA Thermophysics Conference, 2009
Thermal protection system materials for the Mars Science Laboratory (MSL) mission were tested in ... more Thermal protection system materials for the Mars Science Laboratory (MSL) mission were tested in the NASA Ames 60 MW arc jet in a shear environment. Superlight Ablator (SLA-561V) and Phenolic Impregnated Carbon Ablator (PICA) were tested in a wedge and a swept ...
CFD Analysis Framework for Arc-Heated Flowfields II: Shear Testing in Arc-Jets at NASA ARC
41st AIAA Thermophysics Conference, 2009
A three-dimensional framework has been developed for application of tools of computational fluid ... more A three-dimensional framework has been developed for application of tools of computational fluid dynamics to simulate arc-heated flows expanded in convergentdivergent nozzles. Methods that make up the process for prediction of pressure, shear stress, and heat flux on the face ...
Temperature-Independent Strain Measurement Using a Fibre Bragg Grating Written in an Array of Fused Tapers
Optical Fiber Sensors, 2006
Abstract A temperature-independent strain sensor using a fibre Bragg grating written in an array ... more Abstract A temperature-independent strain sensor using a fibre Bragg grating written in an array fused taper is presented. This structure shows a spectrum with several peaks where their relative amplitudes are independent of temperature variations but change with ...
Physics and Simulation of Optoelectronic Devices VII, 1999
Kinetics and mechanism of the aminolysis of S-ethoxycarbonyl O-ethyl dithiocarbonate and related pyrothiocarbonates
Journal of the Chemical Society, Perkin Transactions 2, 1989
The reactions of -ethoxycarbonyl -ethyl dithiocarbonate (), bis(ethoxythiocarbonyl) sulphide (), ... more The reactions of -ethoxycarbonyl -ethyl dithiocarbonate (), bis(ethoxythiocarbonyl) sulphide (), and bis(ethoxycarbonyl) sulphide () with pyrrolidine, piperidine, and morpholine in 95% aqueous ethanol have been subjected to kinetic study. The rate equation found for all the reactions ...
VLSI Circuits and Systems III, 2007
Liquid crystals (LCs) have focused a great attention from industrial and scientific community in ... more Liquid crystals (LCs) have focused a great attention from industrial and scientific community in the last decades. The property of ferroelectricity in liquid crystals was first claimed in 1975. Five years later so-called surface-stabilized ferroelectric liquid crystals were described, which caused a surge in industrial interest because of their promising electro-optical applications. Additionally, antiferroelectricity in liquid crystals (AFLCs) was also
BMC public health, Jan 30, 2004
Malnutrition in children can be a consequence of unfavourable socioeconomic conditions. However, ... more Malnutrition in children can be a consequence of unfavourable socioeconomic conditions. However, some families maintain adequate nutritional status in their children despite living in poverty. The aim of this study was to ascertain whether family-related factors are determinants of stunting in young Mexican children living in extreme poverty, and whether these factors differ between rural or urban contexts. A case-control study was conducted in one rural and one urban extreme poverty level areas in Mexico. Cases comprised stunted children aged between 6 and 23 months. Controls were well-nourished children. Independent variables were defined in five dimensions: family characteristics; family income; household allocation of resources and family organisation; social networks; and child health care. Information was collected from 108 cases and 139 controls in the rural area and from 198 cases and 211 controls in the urban area. Statistical analysis was carried out separately for each ar...
Evolving Neural Controllers for Temporally Dependent Behaviors in Autonomous Robots
Industrial and Engineering Applications of Artificial Intelligence and Expert Systems, 1998
The objective of this work is to study neural control architectures for autonomous robots that ex... more The objective of this work is to study neural control architectures for autonomous robots that explicitly handle time in tasks that require reasoning with the temporal component. The controllers are generated and trained through the methodology of evolutionary robotics. In this study, the reasoning processes are circumscribed to data provided by light sensors, as a first step in the process
El Programa Nacional de Vacunación: orgullo de México
Revista De La Facultad De Medicina, May 10, 2009
... Desde 1991 opera el Programa de Vacunación Universal que ha logrado casi todas sus metas: err... more ... Desde 1991 opera el Programa de Vacunación Universal que ha logrado casi todas sus metas: erradicación de la polio-mielitis, la difteria, el sarampión y el tétanos nenonatal; con-trolar la tos ferina y las formas graves de tuberculosis. ... Page 4. José Ignacio Santos 144 ...
Journal of Artificial Societies and Social Simulation the, 2009
The aim of this paper is to assist researchers in understanding the dynamics of simulation models... more The aim of this paper is to assist researchers in understanding the dynamics of simulation models that have been implemented and can be run in a computer, i.e. computer models. To do that, we start by explaining (a) that computer models are just input-output functions, (b) that every computer model can be re-implemented in many different formalisms (in particular in most programming languages), leading to alternative representations of the same inputoutput relation, and (c) that many computer models in the social simulation literature can be usefully represented as time-homogeneous Markov chains. Then we argue that analysing a computer model as a Markov chain can make apparent many features of the model that were not so evident before conducting such analysis. To prove this point, we present the main concepts needed to conduct a formal analysis of any time-homogeneous Markov chain, and we illustrate the usefulness of these concepts by analysing 10 well-known models in the social simulation literature as Markov chains. These models are: model of spatial segregation Epstein and Axtell's (1996) Sugarscape Miller and Page's (2004) standing ovation model Arthur's (1989) model of competing technologies Axelrod's (1986) metanorms models Takahashi's (2000) model of generalized exchange Axelrod's (1997) model of dissemination of culture Kinnaird's (1946) truels Axelrod and Bennett's (1993) model of competing bimodal coalitions Joyce et al.'s (2006) model of conditional association
Zeitschrift für Analysis und ihre Anwendungen, 2007
In this paper we study the existence of almost periodic and asymptotically almost periodic soluti... more In this paper we study the existence of almost periodic and asymptotically almost periodic solutions for a class of partial neutral functional integro-differential equation with unbounded delay.
Biped locomotion control with evolved adaptive center-crossing continuous time recurrent neural networks
Neurocomputing, 2012
ABSTRACT We used center-crossing continuous time recurrent neural networks as central pattern gen... more ABSTRACT We used center-crossing continuous time recurrent neural networks as central pattern generator controllers in biped robots, together with an adaptive methodology to improve the ability of the recurrent neural networks to produce rhythmic activation behaviors. The parameters of the recurrent networks are adapted or modified in run-time to reach the center-crossing condition, so the nodes get close to the most sensitive region to their input. This facilitates the evolution of the networks that act as central pattern generators to control biped structures. The robustness of the adaptive networks to produce rhythmic activation patterns was checked as well as the improvements and possibilities this adaptation may add.
Implementation of a least-squares multi-harmonic fitting algorithm in the multicore cell processor
2012 IEEE I2MTC - International Instrumentation and Measurement Technology Conference, Proceedings, 2012
Least squares (LS) methods minimize the LS error between a specific data model and an acquired da... more Least squares (LS) methods minimize the LS error between a specific data model and an acquired data set. This is the case of sine-fitting algorithms, which are used to determine the sine wave parameters that best fit an acquired signal. In the case of signals with multiple harmonics, one can use a multi-harmonic fitting algorithm resembling the sine-fitting algorithm to estimate the amplitudes and phases of the harmonics. This paper describes the implementation of a LS multi-harmonic fitting algorithm using the multicore Cell processor to determine the fundamental frequency of a multi-harmonic signal and then the harmonic amplitudes and phases.
Pyrothiocarbonates I. Aminolysis of S-(Ethoxycarbonyl) O-Ethyl Dithiocarbonate
Phosphorus and Sulfur and the Related Elements, 1983
Abstract The reaction of S-(ethoxycarbonyl) O-ethyl dithiocarbonate (1) with equimolar amounts of... more Abstract The reaction of S-(ethoxycarbonyl) O-ethyl dithiocarbonate (1) with equimolar amounts of butylamine, benzylamine, diethylamine and piperidine in ethanol solution at 0° C is reported. The mole ratio of O-ethyl thiocarbamate (2) and O-ethyl carbamate (3) formed ...
Pyrothiocarbonates. Part 2. Reaction of S-ethoxycarbonyl O-ethyl dithiocarbonate with some potassium O-alkylthiocarbonates
Journal of the Chemical Society, Perkin Transactions 1, 1983
ABSTRACT
Thermal Modeling of In-Depth Thermocouple Response in Ablative Heat Shield Materials
26th AIAA Aerodynamic Measurement Technology and Ground Testing Conference, 2008
Page 1. Thermal Modeling of In-Depth Thermocouple Response in Ablative TPS Materials Thermal &... more Page 1. Thermal Modeling of In-Depth Thermocouple Response in Ablative TPS Materials Thermal & Fluids Analysis Workshop (TFAWS 2008) San Jose State University, San Jose, CA August 18, 2008 Jose A. Santos Robin A. Beck Timothy K. Risch Sierra Lobo, Inc. ...
Kinetic study on the aromatic nucleophilic substitution reaction of 3,6-dichloro-1,2,4,5-tetrazine by biothiols
Journal of Physical Organic Chemistry, 2014
ABSTRACT The aromatic nucleophilic substitution reaction of 3,6‐dichloro‐1,2,4,5‐tetrazine (DCT) ... more ABSTRACT The aromatic nucleophilic substitution reaction of 3,6‐dichloro‐1,2,4,5‐tetrazine (DCT) with a series of biothiols RSH: (cysteine, homocysteine, cysteinyl–glycine, N‐acetylcysteine, and glutathione) is subjected to a kinetic investigation. The reactions are studied by following spectrophotometrically the disappearance of DCT at 370 nm. In the case of an excess of N‐acetylcysteine and glutathione, clean pseudo first‐order rate constants (k obs1) are found. However, for cysteine, homocysteine and cysteinyl–glycine, two consecutive reactions are observed. The first one is the nucleophilic aromatic substitution of the chlorine by the sulfhydryl group of these biothiols (RSH) and the second one is the intramolecular and intermolecularnucleophilic aromatic substitutions of their alkylthio with the amine group of RSH to give the di‐substituted compound. Therefore, in these cases, two pseudo first‐order rate constants (k obs1 and k obs2, respectively) are found under biothiol excess. Plots of k obs1 versus free thiol concentration at constant pH are linear, with the slope (k N) independent of pH (from 6.8 to 7.4). The kinetic data analysis (Brønsted‐type plot and activation parameters) is consistent with an addition–elimination mechanism with the nucleophilic attack as the rate‐determining step. Copyright © 2014 John Wiley & Sons, Ltd. The title reaction is subjected to a kinetic investigation. We propose a bimolecular reaction type: addition–elimination (SNAr) for the nucleophilic attack of the series of thiols to tetrazine, in which the formation of the Meisenheimer complex is the rate‐determining step of the reaction. Subsequently, in some cases, a second intramolecular and intermolecular nucleophilic aromatic substitution of alkylthio with the amino group was evidenced.
Tetrahedron, 2006
The pyridinolysis of S-methyl chlorothioformate shows a biphasic Brønsted-type plot, in agreement... more The pyridinolysis of S-methyl chlorothioformate shows a biphasic Brønsted-type plot, in agreement with a stepwise mechanism and a change in the rate-limiting step, from formation of a zwitterionic tetrahedral intermediate (T AE ) at high pK a to its breakdown at low pK a . The reaction of the same substrate with secondary alicyclic amines shows a linear Brønsted-type plot of slope 0.23, which is in accordance with a stepwise mechanism where formation of T AE is the rate-determining step for the whole pK a range examined.
Protein folding with cellular automata in the 3D HP model
Proceeding of the fifteenth annual conference companion on Genetic and evolutionary computation conference companion - GECCO '13 Companion, 2013
ABSTRACT In the difficult ab initio prediction in protein folding only the information of the pri... more ABSTRACT In the difficult ab initio prediction in protein folding only the information of the primary structure of amino acids is used to determine the final folded conformation. The complexity of the interactions and the nature of the amino acid elements are reduced with the use of lattice models like HP, which categorizes the amino acids regarding their hydrophobicity. On the contrary to the intense research performed on the direct prediction of the final folded conformation, our aim here is to model the dynamic and emergent folding process through time, using the scheme of cellular automata but implemented with artificial neural networks optimized with Differential Evolution. Moreover, as the iterative folding also provides the final folded conformation, we can compare the results with those from direct prediction methods of the final protein conformation.
Cellular automata for modeling protein folding using the HP model
2013 IEEE Congress on Evolutionary Computation, 2013
ABSTRACT We used cellular automata (CA) for the modeling of the temporal folding of proteins. Unl... more ABSTRACT We used cellular automata (CA) for the modeling of the temporal folding of proteins. Unlike the focus of the vast research already done on the direct prediction of the final folded conformations, we will model the temporal and dynamic folding process. The CA model defines how the amino acids interact through time to obtain a folded conformation. We employed the TIP model to represent the protein conformations in a lattice, we extended the classical CA models using artificial neural networks for their implementation, and we used evolutionary computing to automatically obtain the models by means of Differential Evolution. Moreover, the modeling of the folding provides the final protein conformation.
Arc Jet Testing in a Shear Environment for Mars Science Laboratory Thermal Protection System
41st AIAA Thermophysics Conference, 2009
Thermal protection system materials for the Mars Science Laboratory (MSL) mission were tested in ... more Thermal protection system materials for the Mars Science Laboratory (MSL) mission were tested in the NASA Ames 60 MW arc jet in a shear environment. Superlight Ablator (SLA-561V) and Phenolic Impregnated Carbon Ablator (PICA) were tested in a wedge and a swept ...
CFD Analysis Framework for Arc-Heated Flowfields II: Shear Testing in Arc-Jets at NASA ARC
41st AIAA Thermophysics Conference, 2009
A three-dimensional framework has been developed for application of tools of computational fluid ... more A three-dimensional framework has been developed for application of tools of computational fluid dynamics to simulate arc-heated flows expanded in convergentdivergent nozzles. Methods that make up the process for prediction of pressure, shear stress, and heat flux on the face ...
Temperature-Independent Strain Measurement Using a Fibre Bragg Grating Written in an Array of Fused Tapers
Optical Fiber Sensors, 2006
Abstract A temperature-independent strain sensor using a fibre Bragg grating written in an array ... more Abstract A temperature-independent strain sensor using a fibre Bragg grating written in an array fused taper is presented. This structure shows a spectrum with several peaks where their relative amplitudes are independent of temperature variations but change with ...
Physics and Simulation of Optoelectronic Devices VII, 1999
Kinetics and mechanism of the aminolysis of S-ethoxycarbonyl O-ethyl dithiocarbonate and related pyrothiocarbonates
Journal of the Chemical Society, Perkin Transactions 2, 1989
The reactions of -ethoxycarbonyl -ethyl dithiocarbonate (), bis(ethoxythiocarbonyl) sulphide (), ... more The reactions of -ethoxycarbonyl -ethyl dithiocarbonate (), bis(ethoxythiocarbonyl) sulphide (), and bis(ethoxycarbonyl) sulphide () with pyrrolidine, piperidine, and morpholine in 95% aqueous ethanol have been subjected to kinetic study. The rate equation found for all the reactions ...
VLSI Circuits and Systems III, 2007
Liquid crystals (LCs) have focused a great attention from industrial and scientific community in ... more Liquid crystals (LCs) have focused a great attention from industrial and scientific community in the last decades. The property of ferroelectricity in liquid crystals was first claimed in 1975. Five years later so-called surface-stabilized ferroelectric liquid crystals were described, which caused a surge in industrial interest because of their promising electro-optical applications. Additionally, antiferroelectricity in liquid crystals (AFLCs) was also
BMC public health, Jan 30, 2004
Malnutrition in children can be a consequence of unfavourable socioeconomic conditions. However, ... more Malnutrition in children can be a consequence of unfavourable socioeconomic conditions. However, some families maintain adequate nutritional status in their children despite living in poverty. The aim of this study was to ascertain whether family-related factors are determinants of stunting in young Mexican children living in extreme poverty, and whether these factors differ between rural or urban contexts. A case-control study was conducted in one rural and one urban extreme poverty level areas in Mexico. Cases comprised stunted children aged between 6 and 23 months. Controls were well-nourished children. Independent variables were defined in five dimensions: family characteristics; family income; household allocation of resources and family organisation; social networks; and child health care. Information was collected from 108 cases and 139 controls in the rural area and from 198 cases and 211 controls in the urban area. Statistical analysis was carried out separately for each ar...
Evolving Neural Controllers for Temporally Dependent Behaviors in Autonomous Robots
Industrial and Engineering Applications of Artificial Intelligence and Expert Systems, 1998
The objective of this work is to study neural control architectures for autonomous robots that ex... more The objective of this work is to study neural control architectures for autonomous robots that explicitly handle time in tasks that require reasoning with the temporal component. The controllers are generated and trained through the methodology of evolutionary robotics. In this study, the reasoning processes are circumscribed to data provided by light sensors, as a first step in the process
El Programa Nacional de Vacunación: orgullo de México
Revista De La Facultad De Medicina, May 10, 2009
... Desde 1991 opera el Programa de Vacunación Universal que ha logrado casi todas sus metas: err... more ... Desde 1991 opera el Programa de Vacunación Universal que ha logrado casi todas sus metas: erradicación de la polio-mielitis, la difteria, el sarampión y el tétanos nenonatal; con-trolar la tos ferina y las formas graves de tuberculosis. ... Page 4. José Ignacio Santos 144 ...
Journal of Artificial Societies and Social Simulation the, 2009
The aim of this paper is to assist researchers in understanding the dynamics of simulation models... more The aim of this paper is to assist researchers in understanding the dynamics of simulation models that have been implemented and can be run in a computer, i.e. computer models. To do that, we start by explaining (a) that computer models are just input-output functions, (b) that every computer model can be re-implemented in many different formalisms (in particular in most programming languages), leading to alternative representations of the same inputoutput relation, and (c) that many computer models in the social simulation literature can be usefully represented as time-homogeneous Markov chains. Then we argue that analysing a computer model as a Markov chain can make apparent many features of the model that were not so evident before conducting such analysis. To prove this point, we present the main concepts needed to conduct a formal analysis of any time-homogeneous Markov chain, and we illustrate the usefulness of these concepts by analysing 10 well-known models in the social simulation literature as Markov chains. These models are: model of spatial segregation Epstein and Axtell's (1996) Sugarscape Miller and Page's (2004) standing ovation model Arthur's (1989) model of competing technologies Axelrod's (1986) metanorms models Takahashi's (2000) model of generalized exchange Axelrod's (1997) model of dissemination of culture Kinnaird's (1946) truels Axelrod and Bennett's (1993) model of competing bimodal coalitions Joyce et al.'s (2006) model of conditional association
Zeitschrift für Analysis und ihre Anwendungen, 2007
In this paper we study the existence of almost periodic and asymptotically almost periodic soluti... more In this paper we study the existence of almost periodic and asymptotically almost periodic solutions for a class of partial neutral functional integro-differential equation with unbounded delay.