Experimental and modeling study of the autoignition of 1-hexene/iso-octane mixtures at low temperatures

Autoignition delay times have been measured in a rapid compression machine at Lille at temperatures after compression from 630 to 840 K, pressures from 8 to 14 bar, \Phi = 1 and for a iso octane/1 hexene mixture containing 82% iso-octane and 18% 1 hexene. Results have shown that this mixture is strongly more reactive than pure iso-octane, but less reactive than pure 1 hexene. It exhibits a classical low temperature behaviour, with the appearance of cool flame and a negative temperature coefficient region. The composition of the reactive mixture obtained after the cool flame has also been determined. A detailed kinetic model has been obtained by using the system EXGAS, developed in Nancy for the automatic generation of kinetic mechanisms, and an acceptable agreement with the experimental results has been obtained both for autoignition delay times and for the distribution of products. A flow rate analysis reveals that the crossed reactions between species coming from both reactants (like H-abstractions or combinations) are negligible in the main flow consumption of the studied hydrocarbons. The ways of formation of the main primary products observed and the most sensitive rate constants have been identified

An evolutive computation solution for the TSP: possible application to organizations

This Thesis researches a possible improvement in the performance of the solution of certain NP-hard combinatorial optimization problems . Examples of these are pure sequencing problems. A summary of conventional methods is presented, and a comparison with those belonging to the field of Evolutive Computation is made. Also, a proposal of eventual improvements to the latter is included. The practical applications discussed in this thesis are strongly related to administration, network design in general, and circuit design.Es revisión de: http://sedici.unlp.edu.ar/handle/10915/4059Resumen de Tesis de la autora presentada para acceder al título de Magister en Automatización de Oficinas (UNLP).Facultad de Informátic

An evolutive computation solution for the TSP: possible application to organizations

This Thesis researches a possible improvement in the performance of the solution of certain NP-hard combinatorial optimization problems . Examples of these are pure sequencing problems. A summary of conventional methods is presented, and a comparison with those belonging to the field of Evolutive Computation is made. Also, a proposal of eventual improvements to the latter is included. The practical applications discussed in this thesis are strongly related to administration, network design in general, and circuit design.Resumen de Tesis de la autora presentada para acceder al título de Magister en Automatización de Oficinas (UNLP).Es revisión de: http://sedici.unlp.edu.ar/handle/10915/4059Facultad de Informátic

ASPECTS OF THE ENERGETICS AND THE MECHANICS OF HUMAN LOCOMOTION

The relationship between the mechanical work performed by the muscles during locomotion and the corresponding metabolic energy consumption is still not completely understood beside the methodological problems and the inherent assumptions in the calculation of both mechanical work and metabolic energy it seems that many factors can affect this relationship. They can be of very different nature depending on muscle structure and composition, body dimension. kinetic and kinematic parameters. The analysis of the mechanical work, in terms of its two component, external work !that done to lift and to accelerate the centre of mass at each step) and internal work (that of accelerating the limbs relative to the body centre of mass), together with the measurement of the metabolic energy consumption, appears a useful approach to better understand the determinants of many characteristics of human locomotion. The relevance of the external and of the internal work has been inferred by altering them separately in particular conditions as in uphill and downhill walking and running or in loaded locomotion (adding 'weight to the trunk or to the limbs).Optimization processes that seem to set the normal speed of walking of unrestrained subjects, the speed of spontaneous transition from walking to running. the frequency freely adopted at a given gait and speed seem better explained on these bases Yet, from the results so far obtained, it appears that neither mechanical work and energy cost are the sole determinants of many aspects of human locomotion

Pedaling rate is an important determinant of human oxygen uptake during exercise on the cycle ergometer.

Estimation of human oxygen uptake (V˙o2) during exercise is often used as an alternative when its direct measurement is not feasible. The American College of Sports Medicine (ACSM) suggests estimating human V˙o2 during exercise on a cycle ergometer through an equation that considers individual's body mass and external work rate, but not pedaling rate (PR). We hypothesized that including PR in the ACSM equation would improve its V˙o2 prediction accuracy. Ten healthy male participants' (age 19-48 years) were recruited and their steady-state V˙o2 was recorded on a cycle ergometer for 16 combinations of external work rates (0, 50, 100, and 150 W) and PR (50, 70, 90, and 110 revolutions per minute). V˙o2 was calculated by means of a new equation, and by the ACSM equation for comparison. Kinematic data were collected by means of an infrared 3-D motion analysis system in order to explore the mechanical determinants of V˙o2. Including PR in the ACSM equation improved the accuracy for prediction of sub-maximal V˙o2 during exercise (mean bias 1.9 vs. 3.3 mL O2 kg(-1) min(-1)) but it did not affect the accuracy for prediction of maximal V˙o2 (P > 0.05). Confirming the validity of this new equation, the results were replicated for data reported in the literature in 51 participants. We conclude that PR is an important determinant of human V˙o2 during cycling exercise, and it should be considered when predicting oxygen consumption

Algoritmo de colonia de abejas artificiales hibridado con algoritmos evolutivos

In this paper, we design, implement, and analysis the replacement of the method to create new solutions in artificial bee colony algorithm by recombination operators, since the original method is similar to the recombination process used in evolutionary algorithms. For that purpose, we present a systematic investigation of the effect of using six different recombination operators for real-coded representations at the employed bee step. All the analysis is carried out using well known test problems. The experimental results suggest that the method to generate a new candidate food position plays an important role in the performance of the algorithm. Computational results and comparisons show that three of the six proposed algorithms are very competitive with the traditional bee colony algorithm.En este trabajo, se ha diseñado, implementado y analizado el reemplazo del método para crear nuevas soluciones en algoritmos basados en colonia de abejas artificiales por operadores de recombinación, ya que el método original es similar al proceso de recombinación usado en los algoritmos evolutivos. Para cumplir con este propósito, se presenta una investigación sistemática del efecto de usar seis operadores de recombinación distintos en el procedimiento llevado a cabo por la abeja empleada. Para la experimentación se utilizan casos de pruebas complejos, habitualmente utilizados en la literatura. Los resultados obtenidos sugieren que el método generador de nuevas fuentes de comida afecta el desempeño del algoritmo. A partir del análisis y comparaciones de los resultados, se observa que tres de las seis propuestas algorítmicas son competitivas con respecto al algoritmo basado en colonia de abejas tradicional.Facultad de Informátic

A phenotypic analysis of three population-based metaheuristics

Metaheuristics are used as very good optimization methods and they imitate natural, biologic, social and cultural process. In this work, we evaluate and compare three different metaheuristics which are population-based: Genetic Algorithms, CHC and Scatter Search. They work with a set of solutions in contrast to trajectory-based metaheuristics which use an only solution. From a comparative analysis, we can infer that Genetic Algorithms and CHC algorithms can solve satisfactorily problems with a growing complexity. While Scatter Search provides high quality solutions but its computational effort is very high too.Workshop de Agentes y Sistemas Inteligentes (WASI)Red de Universidades con Carreras en Informática (RedUNCI

Algoritmo de colonia de abejas artificiales hibridado con algoritmos evolutivos

In this paper, we design, implement, and analysis the replacement of the method to create new solutions in artificial bee colony algorithm by recombination operators, since the original method is similar to the recombination process used in evolutionary algorithms. For that purpose, we present a systematic investigation of the effect of using six different recombination operators for real-coded representations at the employed bee step. All the analysis is carried out using well known test problems. The experimental results suggest that the method to generate a new candidate food position plays an important role in the performance of the algorithm. Computational results and comparisons show that three of the six proposed algorithms are very competitive with the traditional bee colony algorithm.En este trabajo, se ha diseñado, implementado y analizado el reemplazo del método para crear nuevas soluciones en algoritmos basados en colonia de abejas artificiales por operadores de recombinación, ya que el método original es similar al proceso de recombinación usado en los algoritmos evolutivos. Para cumplir con este propósito, se presenta una investigación sistemática del efecto de usar seis operadores de recombinación distintos en el procedimiento llevado a cabo por la abeja empleada. Para la experimentación se utilizan casos de pruebas complejos, habitualmente utilizados en la literatura. Los resultados obtenidos sugieren que el método generador de nuevas fuentes de comida afecta el desempeño del algoritmo. A partir del análisis y comparaciones de los resultados, se observa que tres de las seis propuestas algorítmicas son competitivas con respecto al algoritmo basado en colonia de abejas tradicional.Facultad de Informátic

A modified binary-PSO for continuous optimization

Metaheuristics based on swarm intelligence simulate the behavior of a biological social system like as a flock of birds or a swarm of bees, and they have achieved important advances for solving optimization problems. In this paper, we propose a variant for a particular kind of those metaheurisitcs: Particle Swarm Optimization (PSO). This modification arises after discovering a low rate of convergence produced by a high level of dispersal at the swarm. Finally, we analyzed and compared the results obtained by an original PSO algorithm and our proposal. From those, we can see the improvement obtained by our variant since it allows to explore more the search space.Presentado en el X Workshop Agentes y Sistemas InteligentesRed de Universidades con Carreras en Informática (RedUNCI

Algoritmo de colonia de abejas artificiales hibridado con algoritmos evolutivos

In this paper, we design, implement, and analysis the replacement of the method to create new solutions in artificial bee colony algorithm by recombination operators, since the original method is similar to the recombination process used in evolutionary algorithms. For that purpose, we present a systematic investigation of the effect of using six different recombination operators for real-coded representations at the employed bee step. All the analysis is carried out using well known test problems. The experimental results suggest that the method to generate a new candidate food position plays an important role in the performance of the algorithm. Computational results and comparisons show that three of the six proposed algorithms are very competitive with the traditional bee colony algorithm.En este trabajo, se ha diseñado, implementado y analizado el reemplazo del método para crear nuevas soluciones en algoritmos basados en colonia de abejas artificiales por operadores de recombinación, ya que el método original es similar al proceso de recombinación usado en los algoritmos evolutivos. Para cumplir con este propósito, se presenta una investigación sistemática del efecto de usar seis operadores de recombinación distintos en el procedimiento llevado a cabo por la abeja empleada. Para la experimentación se utilizan casos de pruebas complejos, habitualmente utilizados en la literatura. Los resultados obtenidos sugieren que el método generador de nuevas fuentes de comida afecta el desempeño del algoritmo. A partir del análisis y comparaciones de los resultados, se observa que tres de las seis propuestas algorítmicas son competitivas con respecto al algoritmo basado en colonia de abejas tradicional.Facultad de Informátic