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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

APPLICATION AND APPRAISAL OF A MULTI-OBJECTIVE DECISION SUPPORT SYSTEM FOR THE EVALUATION OF FARM FORESTRY VIABILITY

David Ian Jeffreys Unknown Date (has links)
Abstract This thesis presents innovative applications of Multi-Objective Decision Support Systems (MODSS) to forestry decision support. New MODSS methodologies were developed to assess and evaluate forestry practices and finance regimes. The assessment of forestry investments draw on case studies conducted in the Hodgson Creek catchment on the Darling Downs in south Queensland and on the Atherton Tablelands in north Queensland, Australia. MODSS are systems that aid decision-making, in which a set of alternative management options are evaluated against a set of decision criteria. The criteria, that represent the stakeholders’ goals and objectives, are weighted to reflect stakeholder preferences regarding their relative importance. The weighted criteria scores are then aggregated to create an overall measure of option performance. In the first case study, MODSS procedures identified from the literature as being most suitable to forestry and the MODSS software package DEFINITE was used. After a critical review of the first study, a new MODSS was developed to address the particular needs of forestry evaluations and the weaknesses of current MODSS for addressing these needs. Limitations of the Hodgson Creek MODSS included lack of stakeholder engagement in the MODSS development process, inefficient use of the stakeholder time and an excessive work load on the experts in the scoring process. The new MODSS development process included the combined use of weighted sum and Electré aggregation methods, these being compensatory and non-compensatory aggregation methods. This combination of aggregation methods provided a measure of overall option performance and identified the presence of fatal flaws in the options. Various criteria weighting methods were trialled – including rank order methods, the analytical hierarchy process and direct assessments – to assess their utility for defining weights that reflected stakeholder priorities. A new hybrid weighting technique was developed using a combination of rank order methods and direct assessments. A new and innovative process for scoring options and criteria was developed, using an adaption of the Nominal Group Technique (NGT) in conjunction with a new computer-based Group Decision Support System (GDSS). This iterative process involved repeated rounds of individual scoring and group discussions. In the workshop conducted to elicit scores from experts, the GDSS was used to identify criteria where the elicited scores differed and discussions were focused on these criteria. After the discussions the options were rescored against the criteria and discussed further. This analysis was innovative in that uncertainty around the individual option scores was addressed for the first time using MODSS. This new application was developed in a spreadsheet using the risk analysis package @RISK. Evaluations of forestry options were undertaken at various time scales to address the long delay between incurring costs of tree planting and receiving returns from harvest. The various time scales identify the periods in which environmental and social benefits occurred as the trees grow and the economic benefits occurred at clearfell (or selective) harvest. This thesis specifically focuses on situations where measured and modelled data is not available, and seeks to increase the scientific rigour of the use of expert and stakeholder opinion in MODSS. The MODSS analyses revealed that forestry in the case study areas had the potential to offer considerable economic, environmental and social benefits to both landholders and the wider community. However, these benefits (and the associated costs) were not viewed as equally important. The MODSS developed in this study addressed these concerns. The benefits and costs of an option were reflected in its performance against the criteria. The degree of importance of the individual criteria varied from minor to high and overriding all other considerations. Criteria against which an option performed highly (the option’s strengths) were identified, as were criteria against which an option performed poorly (the option’s weaknesses). When these weaknesses occurred in highly important criteria, these were identified as fatal flaws in the option. The first case study in the Hodgson Creek catchment considered eight forestry options against 17 economic criteria, 12 environmental criteria and 12 social criteria. The second case study on the Atherton Tablelands considered 16 forestry options against eight economic criteria, six environmental criteria and five social criteria. The MODSS analysis identified the most preferred forestry options and the strengths and weaknesses of the options. In both case studies the most preferred options were large or medium-sized plantations with monoculture plantings with an element of non-landholder funding, in the form of government funding, joint ventures or land leasing agreements. These options had the highest performance against the economic criteria at all time scales and satisfactory environmental and social performance. Other forestry options that performed well included plantings focused on under-utilised land areas and salinity prevention areas, agroforestry, and selective harvesting of private native forest. These options generally had a higher level of performance against the social and environmental criteria, but lower levels of performance against economic criteria. These plantings would be undertaken for environmental and social reasons and not for financial returns. The application of MODSS developed in this thesis presents a significant scientific contribution to MODSS methodology. This thesis includes: the use of multiple time-periods to address the temporal differences in the delivery of benefits and costs, the use of NGT and a GDSS to provide a process for rapidly eliciting expert opinion, and the use of the combination of Electré and weighted sum aggregation methods to provide an overall measure of option performance and to identify fatal flaws in the options.
2

APPLICATION AND APPRAISAL OF A MULTI-OBJECTIVE DECISION SUPPORT SYSTEM FOR THE EVALUATION OF FARM FORESTRY VIABILITY

David Ian Jeffreys Unknown Date (has links)
Abstract This thesis presents innovative applications of Multi-Objective Decision Support Systems (MODSS) to forestry decision support. New MODSS methodologies were developed to assess and evaluate forestry practices and finance regimes. The assessment of forestry investments draw on case studies conducted in the Hodgson Creek catchment on the Darling Downs in south Queensland and on the Atherton Tablelands in north Queensland, Australia. MODSS are systems that aid decision-making, in which a set of alternative management options are evaluated against a set of decision criteria. The criteria, that represent the stakeholders’ goals and objectives, are weighted to reflect stakeholder preferences regarding their relative importance. The weighted criteria scores are then aggregated to create an overall measure of option performance. In the first case study, MODSS procedures identified from the literature as being most suitable to forestry and the MODSS software package DEFINITE was used. After a critical review of the first study, a new MODSS was developed to address the particular needs of forestry evaluations and the weaknesses of current MODSS for addressing these needs. Limitations of the Hodgson Creek MODSS included lack of stakeholder engagement in the MODSS development process, inefficient use of the stakeholder time and an excessive work load on the experts in the scoring process. The new MODSS development process included the combined use of weighted sum and Electré aggregation methods, these being compensatory and non-compensatory aggregation methods. This combination of aggregation methods provided a measure of overall option performance and identified the presence of fatal flaws in the options. Various criteria weighting methods were trialled – including rank order methods, the analytical hierarchy process and direct assessments – to assess their utility for defining weights that reflected stakeholder priorities. A new hybrid weighting technique was developed using a combination of rank order methods and direct assessments. A new and innovative process for scoring options and criteria was developed, using an adaption of the Nominal Group Technique (NGT) in conjunction with a new computer-based Group Decision Support System (GDSS). This iterative process involved repeated rounds of individual scoring and group discussions. In the workshop conducted to elicit scores from experts, the GDSS was used to identify criteria where the elicited scores differed and discussions were focused on these criteria. After the discussions the options were rescored against the criteria and discussed further. This analysis was innovative in that uncertainty around the individual option scores was addressed for the first time using MODSS. This new application was developed in a spreadsheet using the risk analysis package @RISK. Evaluations of forestry options were undertaken at various time scales to address the long delay between incurring costs of tree planting and receiving returns from harvest. The various time scales identify the periods in which environmental and social benefits occurred as the trees grow and the economic benefits occurred at clearfell (or selective) harvest. This thesis specifically focuses on situations where measured and modelled data is not available, and seeks to increase the scientific rigour of the use of expert and stakeholder opinion in MODSS. The MODSS analyses revealed that forestry in the case study areas had the potential to offer considerable economic, environmental and social benefits to both landholders and the wider community. However, these benefits (and the associated costs) were not viewed as equally important. The MODSS developed in this study addressed these concerns. The benefits and costs of an option were reflected in its performance against the criteria. The degree of importance of the individual criteria varied from minor to high and overriding all other considerations. Criteria against which an option performed highly (the option’s strengths) were identified, as were criteria against which an option performed poorly (the option’s weaknesses). When these weaknesses occurred in highly important criteria, these were identified as fatal flaws in the option. The first case study in the Hodgson Creek catchment considered eight forestry options against 17 economic criteria, 12 environmental criteria and 12 social criteria. The second case study on the Atherton Tablelands considered 16 forestry options against eight economic criteria, six environmental criteria and five social criteria. The MODSS analysis identified the most preferred forestry options and the strengths and weaknesses of the options. In both case studies the most preferred options were large or medium-sized plantations with monoculture plantings with an element of non-landholder funding, in the form of government funding, joint ventures or land leasing agreements. These options had the highest performance against the economic criteria at all time scales and satisfactory environmental and social performance. Other forestry options that performed well included plantings focused on under-utilised land areas and salinity prevention areas, agroforestry, and selective harvesting of private native forest. These options generally had a higher level of performance against the social and environmental criteria, but lower levels of performance against economic criteria. These plantings would be undertaken for environmental and social reasons and not for financial returns. The application of MODSS developed in this thesis presents a significant scientific contribution to MODSS methodology. This thesis includes: the use of multiple time-periods to address the temporal differences in the delivery of benefits and costs, the use of NGT and a GDSS to provide a process for rapidly eliciting expert opinion, and the use of the combination of Electré and weighted sum aggregation methods to provide an overall measure of option performance and to identify fatal flaws in the options.
3

APPLICATION AND APPRAISAL OF A MULTI-OBJECTIVE DECISION SUPPORT SYSTEM FOR THE EVALUATION OF FARM FORESTRY VIABILITY

David Ian Jeffreys Unknown Date (has links)
Abstract This thesis presents innovative applications of Multi-Objective Decision Support Systems (MODSS) to forestry decision support. New MODSS methodologies were developed to assess and evaluate forestry practices and finance regimes. The assessment of forestry investments draw on case studies conducted in the Hodgson Creek catchment on the Darling Downs in south Queensland and on the Atherton Tablelands in north Queensland, Australia. MODSS are systems that aid decision-making, in which a set of alternative management options are evaluated against a set of decision criteria. The criteria, that represent the stakeholders’ goals and objectives, are weighted to reflect stakeholder preferences regarding their relative importance. The weighted criteria scores are then aggregated to create an overall measure of option performance. In the first case study, MODSS procedures identified from the literature as being most suitable to forestry and the MODSS software package DEFINITE was used. After a critical review of the first study, a new MODSS was developed to address the particular needs of forestry evaluations and the weaknesses of current MODSS for addressing these needs. Limitations of the Hodgson Creek MODSS included lack of stakeholder engagement in the MODSS development process, inefficient use of the stakeholder time and an excessive work load on the experts in the scoring process. The new MODSS development process included the combined use of weighted sum and Electré aggregation methods, these being compensatory and non-compensatory aggregation methods. This combination of aggregation methods provided a measure of overall option performance and identified the presence of fatal flaws in the options. Various criteria weighting methods were trialled – including rank order methods, the analytical hierarchy process and direct assessments – to assess their utility for defining weights that reflected stakeholder priorities. A new hybrid weighting technique was developed using a combination of rank order methods and direct assessments. A new and innovative process for scoring options and criteria was developed, using an adaption of the Nominal Group Technique (NGT) in conjunction with a new computer-based Group Decision Support System (GDSS). This iterative process involved repeated rounds of individual scoring and group discussions. In the workshop conducted to elicit scores from experts, the GDSS was used to identify criteria where the elicited scores differed and discussions were focused on these criteria. After the discussions the options were rescored against the criteria and discussed further. This analysis was innovative in that uncertainty around the individual option scores was addressed for the first time using MODSS. This new application was developed in a spreadsheet using the risk analysis package @RISK. Evaluations of forestry options were undertaken at various time scales to address the long delay between incurring costs of tree planting and receiving returns from harvest. The various time scales identify the periods in which environmental and social benefits occurred as the trees grow and the economic benefits occurred at clearfell (or selective) harvest. This thesis specifically focuses on situations where measured and modelled data is not available, and seeks to increase the scientific rigour of the use of expert and stakeholder opinion in MODSS. The MODSS analyses revealed that forestry in the case study areas had the potential to offer considerable economic, environmental and social benefits to both landholders and the wider community. However, these benefits (and the associated costs) were not viewed as equally important. The MODSS developed in this study addressed these concerns. The benefits and costs of an option were reflected in its performance against the criteria. The degree of importance of the individual criteria varied from minor to high and overriding all other considerations. Criteria against which an option performed highly (the option’s strengths) were identified, as were criteria against which an option performed poorly (the option’s weaknesses). When these weaknesses occurred in highly important criteria, these were identified as fatal flaws in the option. The first case study in the Hodgson Creek catchment considered eight forestry options against 17 economic criteria, 12 environmental criteria and 12 social criteria. The second case study on the Atherton Tablelands considered 16 forestry options against eight economic criteria, six environmental criteria and five social criteria. The MODSS analysis identified the most preferred forestry options and the strengths and weaknesses of the options. In both case studies the most preferred options were large or medium-sized plantations with monoculture plantings with an element of non-landholder funding, in the form of government funding, joint ventures or land leasing agreements. These options had the highest performance against the economic criteria at all time scales and satisfactory environmental and social performance. Other forestry options that performed well included plantings focused on under-utilised land areas and salinity prevention areas, agroforestry, and selective harvesting of private native forest. These options generally had a higher level of performance against the social and environmental criteria, but lower levels of performance against economic criteria. These plantings would be undertaken for environmental and social reasons and not for financial returns. The application of MODSS developed in this thesis presents a significant scientific contribution to MODSS methodology. This thesis includes: the use of multiple time-periods to address the temporal differences in the delivery of benefits and costs, the use of NGT and a GDSS to provide a process for rapidly eliciting expert opinion, and the use of the combination of Electré and weighted sum aggregation methods to provide an overall measure of option performance and to identify fatal flaws in the options.
4

Técnicas de agregação de demandas repetitivas: uma análise comparativa da experiência norte-americana em busca da eficiência processual / Aggregation techniques for repetitive litigation: a compared analisys with the American law in the search of procedural efficiency

Farina, Fernanda Mercier Querido 27 May 2014 (has links)
Essa pesquisa se destina a discutir a crise de eficiência por qual passa o Poder Judiciário brasileiro, decorrente dos processos repetitivos, e as soluções processuais para buscar amenizá-la. Primeiramente far-se-á uma análise da situação atual dos tribunais nacionais, da carga de trabalho e dos efeitos da crise de eficiência na demora da prestação jurisdicional, bem como na sua influência maléfica nos direitos e garantias fundamentais ao acesso à justiça plena. Posteriormente, em busca de soluções, far-se-á uma análise comparada de instrumentos de agregação de demandas repetitivas dos Estados Unidos com os instrumentos correlatos do Brasil. Os institutos escolhidos para análise, diga-se, aqueles que se compreende serem os mais adequados no intento de solucionar as demandas repetitivas, subdividem-se em dois grupos: aqueles destinados a resolver processos oriundos da mesma questão de fato a coletivização e aqueles destinados a resolver processos envolvendo exclusivamente a mesma questão de direito vinculação de precedentes. Dessa maneira, de um lado estudar-se-á a class action, de modo a extrair dela os instrumentos necessários a fim de conferir aos institutos brasileiros de coletivização, particularmente à ação civil pública para tutela de direitos individuais homogêneos, maior eficiência para solução de conflitos repetitivos. Objetivando-se, sempre, imprimir eficácia, segurança jurídica e celeridade ao processo. De outro lado analisar-se-á o stare decisis, fazendo-se um paralelo com a jurisprudência vinculante e a experiência brasileira no manuseio da jurisprudência súmula vinculante, súmula persuasiva etc. A conclusão buscará encontrar na experiência dos institutos de agregação norteamericanos ensinamentos que possam contribuir de forma positiva com os institutos brasileiros de modo a conferir eficiência no manuseio das causas repetitivos, reduzindo, assim, o congestionamento do Poder Judiciário. / This research aims to discuss the efficiency crisis that affects the Judiciary Power in Brazil due to repetitive litigation and the procedural solutions thought to solve it. First of all, it will be analyzed the actual situation of Brazilian Courts: workloads delay in the jurisdictional answer, as well as the direct consequences of delay on the due process and right to one day in court. Secondly, in search of solutions, this research will do a compared analysis of the aggregation techniques for solving repetitive litigation in the United States and in Brazil. The techniques chosen for study, those that are thought to be the best ones in the aim of bringing efficiency to civil procedure, are subdivided into two groups: the ones destined to solving procedures born from the same transaction or occurrence preclusion mechanisms and secondly, the ones destined to solving procedures uniquely discussing the same question of law stare decisis. Therefore, the study shall be divided into three chapters: one for problematic, one for studding the class action and one for stare decisis. The class action will be compared with the Brazilian technique for solving mass tort cases (ação civil pública para tutela de interesses individuais homogêneos), suggesting modifications and improvements in the Brazilian legislation starting by the American class action study. Finally, stare decisis will be compared with the Brazilian experience with dealing with jurisprudence and mandatory case law. All of it in the aim of finding the best technique for solving repetitive litigation and improving the Brazilian procedural system, with efficiency and fairness
5

Sur la stabilisation de systèmes dynamiques continus non linéaires exploitant les matrices de formes en flèche : application à la synchronisation de systèmes chaotiques / On the stabilization of nonlinear continuous dynamical systems using the arrow forms matrices : application to the synchronization of chaotic systems

Hammami, Sonia 21 December 2009 (has links)
Les travaux effectués, dans le cadre de cette thèse, concernent l’analyse et la synthèse de systèmes dynamiques continus complexes de grande dimension. Pour la classe des systèmes étudiés, est mise en exergue en particulier l’importance du choix de la description des systèmes sur l’étendue des résultats pouvant être obtenus lorsque la méthode d’étude de la stabilité est fixée.L’utilisation des normes vectorielles comme fonction d’agrégation et du critère pratique de Borne et Gentina pour l’étude de la stabilité, associée à la description des systèmes par des matrices caractéristiques de forme en flèche, a permis l’élaboration de nouvelles conditions suffisantes de stabilisabilité de systèmes dynamiques continus non linéaires, monovariables et multivariables, formulées en théorèmes et corollaires.Ces résultats obtenus, pour une classe de processus, pouvant être caractérisés par des matrices instantanées de forme en flèche mince, ont été généralisés au cas des matrices quelconques, pouvant être mises sous forme en flèche mince généralisée ou en flèche épaisse.Les critères élaborés, soit pour l’analyse de la stabilité soit pour la synthèse d’une loi de commande stabilisante, sont ensuite exploités, avec succès, pour la formulation de nouvelles conditions suffisantes de vérification des propriétés de synchronisation, d’anti-synchronisation et de synchronisation hybride de systèmes chaotiques du type maître-esclave, d’un grand intérêt, en particulier, pour garantir une transmission sécurisée / This Thesis deals with the analysis and the synthesis of dynamic large scale continuous systems depending on the choice of the system description.Stability and stabilisability proposed studies are based on the use of vector norms as an aggregation function and of the practical Borne-Gentina criterion, associated to the description of the system by instantaneous characteristic matrix in arrow form.Practical stability conditions, easy to use, are obtained for both dynamic nonlinear continuous single input single output systems and multiple inputs multiple outputs ones, formulated by means of theorems and corollaries. These obtained results for thin arrow form, are generalized to the case of matrices, which can be putted under thin generalized arrow form or thick arrow form. The proposed stability and stabilisability criteria are afterwards, successfully, exploited to formulate new sufficient conditions, guaranteeing the synchronization, the anti-synchronization and the hybrid synchronization properties, for chaotic master-slave systems, having an increasing interest throughout their application in the secure communication field
6

Técnicas de agregação de demandas repetitivas: uma análise comparativa da experiência norte-americana em busca da eficiência processual / Aggregation techniques for repetitive litigation: a compared analisys with the American law in the search of procedural efficiency

Fernanda Mercier Querido Farina 27 May 2014 (has links)
Essa pesquisa se destina a discutir a crise de eficiência por qual passa o Poder Judiciário brasileiro, decorrente dos processos repetitivos, e as soluções processuais para buscar amenizá-la. Primeiramente far-se-á uma análise da situação atual dos tribunais nacionais, da carga de trabalho e dos efeitos da crise de eficiência na demora da prestação jurisdicional, bem como na sua influência maléfica nos direitos e garantias fundamentais ao acesso à justiça plena. Posteriormente, em busca de soluções, far-se-á uma análise comparada de instrumentos de agregação de demandas repetitivas dos Estados Unidos com os instrumentos correlatos do Brasil. Os institutos escolhidos para análise, diga-se, aqueles que se compreende serem os mais adequados no intento de solucionar as demandas repetitivas, subdividem-se em dois grupos: aqueles destinados a resolver processos oriundos da mesma questão de fato a coletivização e aqueles destinados a resolver processos envolvendo exclusivamente a mesma questão de direito vinculação de precedentes. Dessa maneira, de um lado estudar-se-á a class action, de modo a extrair dela os instrumentos necessários a fim de conferir aos institutos brasileiros de coletivização, particularmente à ação civil pública para tutela de direitos individuais homogêneos, maior eficiência para solução de conflitos repetitivos. Objetivando-se, sempre, imprimir eficácia, segurança jurídica e celeridade ao processo. De outro lado analisar-se-á o stare decisis, fazendo-se um paralelo com a jurisprudência vinculante e a experiência brasileira no manuseio da jurisprudência súmula vinculante, súmula persuasiva etc. A conclusão buscará encontrar na experiência dos institutos de agregação norteamericanos ensinamentos que possam contribuir de forma positiva com os institutos brasileiros de modo a conferir eficiência no manuseio das causas repetitivos, reduzindo, assim, o congestionamento do Poder Judiciário. / This research aims to discuss the efficiency crisis that affects the Judiciary Power in Brazil due to repetitive litigation and the procedural solutions thought to solve it. First of all, it will be analyzed the actual situation of Brazilian Courts: workloads delay in the jurisdictional answer, as well as the direct consequences of delay on the due process and right to one day in court. Secondly, in search of solutions, this research will do a compared analysis of the aggregation techniques for solving repetitive litigation in the United States and in Brazil. The techniques chosen for study, those that are thought to be the best ones in the aim of bringing efficiency to civil procedure, are subdivided into two groups: the ones destined to solving procedures born from the same transaction or occurrence preclusion mechanisms and secondly, the ones destined to solving procedures uniquely discussing the same question of law stare decisis. Therefore, the study shall be divided into three chapters: one for problematic, one for studding the class action and one for stare decisis. The class action will be compared with the Brazilian technique for solving mass tort cases (ação civil pública para tutela de interesses individuais homogêneos), suggesting modifications and improvements in the Brazilian legislation starting by the American class action study. Finally, stare decisis will be compared with the Brazilian experience with dealing with jurisprudence and mandatory case law. All of it in the aim of finding the best technique for solving repetitive litigation and improving the Brazilian procedural system, with efficiency and fairness
7

Sur la synchronisation et le cryptage de systèmes chaotiques à temps discret utilisant les techniques d'agrégation et la représentation en flèche des matrices / On synchronization and encryption of discrete-time chaotic systems using aggregation techniques and representation of arrow form matrices

Filali, Rania Linda 04 June 2013 (has links)
L’objectif de cette thèse était de développer une méthode de synthèse de commande par retour d’état puis par observateurs offrant des conditions de synthèse non contraignantes dans le cas de systèmes non linéaires à temps discret. Dans cette méthode, est mise en exergue l’importance du choix de la description des systèmes sur l’étendue des résultats pouvant être obtenus lorsque la méthode d’étude de la stabilité est fixée. Ainsi l’utilisation des normes vectorielles comme fonction d’agrégation et du critère pratique de Borne et Gentina pour l’étude de la stabilité, associée à la description des systèmes par des matrices caractéristiques de forme en flèche de Benrejeb, a conduit à l’élaboration de nouvelles conditions suffisantes de stabilisation de systèmes dynamiques discrets non linéaires, formulées en théorèmes et corollaires. Ces résultats obtenus, sont ensuite exploités, avec succès, pour la formulation de nouvelles conditions suffisantes de vérification des propriétés de synchronisation pour les systèmes hyperchaotiques à temps discrets. Ensuite, le cas de synthèse d’observateur est validé dans deux types de transmission chaotique / The objective of this thesis was to develop a method for synthesizing control state feedback and observers by offering soft synthesis conditions in the case of nonlinear discrete-time systems. In this method, is highlighting the importance of choosing the systems description of the scope of what can be achieved when the stability study method is fixed. The use of of vector norms as an aggregation function and the practical Borne-Gentina criterion for stability study, associated to arrow form matrix of Benrejeb for system discription, lead to the development of new sufficient conditions for stabilization of nonlinear discrete dynamical systems, formulated as theorems and corollaries. These results are then used, with success, for the formulation of new sufficient conditions for checking properties of hyperchaotiques synchronization for discrete-time systems. Then, the synthesis of observer is validated in two types of chaotic transmission
8

Sur la stabilité et l’estimation des attracteurs de systèmes complexes fortement nonlinéaires / Stability and estimation attractors of nonlinear complex systems

Gharbi, Amira 04 June 2013 (has links)
Les travaux effectués dans le cadre de cette thèse présentent une nouvelle approche permettant d’estimer et si possible minimiser l’écart maximum de la sortie par rapport à l’objectif dans le cas des processus non linéaires pour lesquels il n’est pas toujours possible de déterminer une commande permettant d’atteindre exactement un objectif donné.Le concept de norme vectorielle, associé à la définition des systèmes de comparaison par l'approche de la stabilité Borne et Gentina, et le choix de la représentation matricielle qui s’avère particulièrement importante pour l’étude de la stabilité, est proposé dans ce travail, avec succès, pour étudier la stabilité des processus complexes de modèles éventuellement incertainsNous avons défini une technique d’estimation des attracteurs caractérisant le maximum de l’erreur par rapport à l’objectif et par la prise en compte des résultats ainsi obtenus de les affiner par des itérations successives de la procédure présentée.Dans la recherche de commandes, l’approche a été réalisée en définissant celle-ci par retours d’état calculés soit directement, soit à partir d’une linéarisation du modèle du processus dans le voisinage de l’objectif. Une attention toute particulière a été accordée aux processus du type Lur’e Postnikov / A new approach of the estimation of the error between the desired output of a nonlinear complex system and the real one’s is studied by the use of Borne-Gentina vector norm approach and the Benrejeb arrow form description.A new technique of definition of the attractors characterizing the precision of control laws is defined, implementing successive improved determinations. The research of control laws by various types of state or output feedback in presence of uncertainties is proposed, based on a local linearization and control of the system.A special attention has been devoted to the control of nonlinear Lur’e Postnikov type systems

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