735 research outputs found
ON NECESSARY CONDITIONS FOR EFFICIENCY IN DIRECTIONALLY DIFFERENTIABLE OPTIMIZATION PROBLEMS
Get PDFThis paper deals with multiobjective programming problems with in- equality, equality and set constraints involving Dini or Hadamard differentiable func- tions. A theorem of the alternative of Tucker type is established, and from which Kuhn-Tucker necessary conditions for local Pareto minima with positive Lagrange multipliers associated with all the components of objective functions are derived.Theorem of the alternative, Kuhn-Tucker necessary conditions, direc- tionally differentiable functions.
Biodiesel production from Tung oil and blended oil via ultrasonic transesterification process
No full textParameter evaluation of biodiesel production from unblended and blended Tung oils via ultrasound-assisted process
No full textThe Role of Savings and Income Diversification in Households’ Resilience Strategies: Evidence from Rural Vietnam
No full textUnderstanding households' resilience-building strategies is vital for the domains of humanitarian assistance, economic development, and poverty reduction, especially in the places where are vulnerable to shocks. In this study, we offer the first trial that takes into account the correlation between households' risk attitude and their resilience-building strategies, namely savings as an absorptive capacity and income diversification as an adaptive capacity. We examine the effects of these resilience strategies on reducing the impacts of shocks and poverty. We use a panel data of 1227 identical households for Vietnam in two waves of the Thailand–Vietnam Socio-Economic Panel project to investigate the above issues. We address the endogenous problems of households' risk attitude, savings, and income diversification. Our results show that more risk-averse households tend to save more and diversify their income portfolios. These precautionary strategies to build up their resilience capacity help prevent them from reducing consumption caused by shocks and from falling into poverty in absolute, relative, and multidimensional measures. We suggest that rural development policies in developing countries should focus on facilitating more income generation and employment opportunities. Furthermore, the development of rural education and infrastructure for information and communication technology should be taken into account of designing poverty reduction programs
Relating permeability and electrical conductivity in partially saturated porous media by means of the Johnson–Koplik–Schwartz characteristic length
Get PDFIn this work, we revisit the seminal concept of Johnson-Koplik-Schwartz (JKS) length Λ, i.e. a characteristic length representing an effective pore size which controls various transport-related properties of porous media, such as, the permeability and the electrical conductivity. We present a novel closed-form equation that predicts the behavior of Λ in partially saturated media, for different saturation states. Using previous models in the literature that predict the intrinsic and relative electrical conductivities under partially saturated conditions, we infer the JKS length Λ and the electrical formation factor F as functions of water saturation and properties associated with the pore-size distribution of the probed porous medium. The proposed method permits to estimate the effective permeability and the relative permeability directly from electrical conductivity measurements, thus opening new-avenues for the remote characterization of partially saturated media. We believe that this new model will prove useful for various characterization and modeling applications from reservoir (CO2 or hydrogen storage) to vadose zone studies.Fil: Duy Luong, Thanh. Thuyloi University; VietnamFil: Jougnot, Damien. Sorbonne University; FranciaFil: Solazzi, Santiago Gabriel. Universite de Lausanne; Suiza. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Luo, Haoliang. Sorbonne University; FranciaFil: Hung, Nguyen Manh. Thuyloi University; VietnamFil: Van Nghia, Nguyen. Thuyloi University; VietnamFil: Van Do, Phan. Thuyloi University; VietnamFil: Huong, Luong Thi Thanh. Thuyloi University; Vietna
Robust observer designs for singular linear parameter-varying systems
No full textCette thèse s'inscrit dans le cadre de l'étude de l'estimation d'état et des défauts des systèmes dynamiques Linéaires à Paramètres Variants (LPV). La thèse s'attache à considérer deux classes de systèmes : les systèmes réguliers et les systèmes singuliers. Les estimateurs proposés sont synthétisés pour être robustes aux incertitudes paramétriques, aux perturbations présentes sur l'équation d'état et de sortie, aux bruits de mesures, aux non-linéarités Lipchitziennes et aux retards. Les contributions majeures de ses travaux sont respectivement : la conception simultanée d'un régulateur et d'un observateur pour un système LPV incertain avec l'atténuation des perturbations par modelage fréquentielle des sorties, la conception d'observateurs pour l'estimation des défaillances/dégradations avec découplage partiel des entrées inconnues, la synthèse H∞ et H2 d'observateurs réguliers pour les systèmes singuliers avec entrée Lipchitzienne, et la synthèse H∞ d'un observateur régulier pour un système LPV à retards. La qualité des estimations est validée avec des données de terrain (plateforme INOVE) et des exemples numériques.This Thesis is focused on the study of state and fault estimation in Linear Parameter-Varying (LPV) systems. The Thesis considers two classes of systems: non-singular and singular systems. In specific, the proposed observers are synthesized to be robust against parametric uncertainties, input and output disturbances, measurement noise, Lipschitz nonlinearities, and time delays. The major contributions of this research are respectively: an integrated observer-controller design for uncertain LPV systems with a new methodology of disturbance attenuation called output frequency-shaping filter; the design and the development of unknown input (UI) observers for fault estimation under the existence of partially decoupled UIs; the synthesis of H∞ and H2 observers for the singular system with Lipschitz nonlinearity; and a H∞ observer design for time-delay LPV system. Finally, the performance of the proposed methods is justified by laboratory experiments with INOVE platform and numerical examples
Saving up and diversifying income for a rainy day: Implications for households' resilience strategies and poverty
No full textUnderstanding households' resilience-building strategies is vital for the domains of humanitarian assistance, economic development, and poverty reduction, especially in the places where are vulnerable to shocks. In this study, we assess the correlation between households' risk attitude and their resilience-building strategies, namely savings as an absorptive capacity and income diversification as an adaptive capacity. We examine the effects of these resilience strategies on reducing the impacts of shocks and poverty. We use a panel data of 1227 identical households for Vietnam in two waves of the Thailand Vietnam Socio Economic Panel (TVSEP) project to investigate the above issues. Our results from instrumental variable (IV) estimations show that more risk-adverse households tend to save more and diversify their income portfolios. These precautionary strategies to build up their resilience capacity help prevent them from reducing consumption to cope with shocks and from falling into poverty in absolute, relative, and multidimensional measures. We suggest that rural development policies in developing countries should focus on facilitating more income generation and employment opportunities. Furthermore, the development of rural education and infrastructure for information and communication technology (ICT) should be taken into account of designing poverty reduction programs
Synthèse robuste d'observateurs pour systèmes singuliers linéaires à paramètres variants
No full textThis Thesis is focused on the study of state and fault estimation in Linear Parameter-Varying (LPV) systems. The Thesis considers two classes of systems: non-singular and singular systems. In specific, the proposed observers are synthesized to be robust against parametric uncertainties, input and output disturbances, measurement noise, Lipschitz nonlinearities, and time delays. The major contributions of this research are respectively: an integrated observer-controller design for uncertain LPV systems with a new methodology of disturbance attenuation called output frequency-shaping filter; the design and the development of unknown input (UI) observers for fault estimation under the existence of partially decoupled UIs; the synthesis of H∞ and H2 observers for the singular system with Lipschitz nonlinearity; and a H∞ observer design for time-delay LPV system. Finally, the performance of the proposed methods is justified by laboratory experiments with INOVE platform and numerical examples.Cette thèse s'inscrit dans le cadre de l'étude de l'estimation d'état et des défauts des systèmes dynamiques Linéaires à Paramètres Variants (LPV). La thèse s'attache à considérer deux classes de systèmes : les systèmes réguliers et les systèmes singuliers. Les estimateurs proposés sont synthétisés pour être robustes aux incertitudes paramétriques, aux perturbations présentes sur l'équation d'état et de sortie, aux bruits de mesures, aux non-linéarités Lipchitziennes et aux retards. Les contributions majeures de ses travaux sont respectivement : la conception simultanée d'un régulateur et d'un observateur pour un système LPV incertain avec l'atténuation des perturbations par modelage fréquentielle des sorties, la conception d'observateurs pour l'estimation des défaillances/dégradations avec découplage partiel des entrées inconnues, la synthèse H∞ et H2 d'observateurs réguliers pour les systèmes singuliers avec entrée Lipchitzienne, et la synthèse H∞ d'un observateur régulier pour un système LPV à retards. La qualité des estimations est validée avec des données de terrain (plateforme INOVE) et des exemples numériques
Observation et commande tolérante aux fautes pour la dynamique verticale d'un mini véhicule équipé de suspensions semi-actives
No full textIn this Final Year Project (FYP), we are looking to validate the control approaches on the platform INOVE which is available in the laboratory. It allows us to study the behavior of a vehicle via the inuence of roll and pitch angles and vertical movement of the car. The vehicle is equipped with semi-active suspensions with Electro-Rheological damper, in order to control in real time the damping behavior of the suspension. The project's objective is to develop control approaches for the synthesis of control laws which is tolerant to sensor faults. Following by this study, an international benchmark will be developed in order to verify the control laws .The project has four major parts. Firstly, the studies on semi-active suspension must be done in order to modeling it by mathematical and physical equations. Secondly, the strategies for fault detection and diagnostics are realized in order to locate and estimate the sensor fault. Thirdly, we develop the control input type FTC (fault-tolerant control) in order to assure the normal working state of the semi-active suspension against the sensor faults. Finally, thanks to experiments with platform INOVE, we can verify the performance of the strategies and the controller. A benchmark is proposed at the end of this project.In collaboration with CRAN Nancy and the Academy of Sciences of Budapest, the project is realized under the supervision of Mr SENAME Olivier and Mr KOENIG Damien at GIPSA-lab in Grenoble for a period of 5 months, from 01/02/2017 to 05/07/2017
Rural development policies in Southeast Asia: impacts on household livelihoods, welfare and rural transformation
Get PDFStructural change in agriculture is an essential part of economic development in developing countries. The process of structural change is characterized by the shift of labor from agriculture to non-agriculture sectors which leads to higher income from non-farm sources. Within the agricultural sector, structural change can influence the application of mechanization and improve income from farm sources of households who remain in the sector. In developing countries, agriculture plays a significant role in rural households’ livelihoods, hence, structural change can also be considered as agricultural transformation or rural transformation. Studying how rural development policies, for instance promoting investments in rural infrastructure, can accompany the structural change is vital for a successful transformation of agriculture and rural areas.
Vietnam is a good example to study rural development policies and structural change. First, this country is famous for its rapid economic growth, but a large proportion of the country’s population live in rural areas and rely on agriculture as the main income source. Second, the country has officially introduced a new rural development (NRD) policy since 2010 to solve critical issues in rural areas. In 2022, the government of Vietnam extended this national program for the next phase, up to 2025. Hence, the question arises whether the past investments are significant for improving rural households’ income and welfare. Finally, the rural population in this country is even more vulnerable due to extreme weather events and health shocks. Therefore, this dissertation aims to provide empirical evidence on how this NRD policy can help increase rural households’ income, improve their welfare and resilience against shocks, and reduce poverty, while accelerating structural transformation in rural areas. If investments in rural infrastructure can help solve critical problems in rural areas, this dissertation also aims to shed light on which areas of the rural investments and policy improvements should be implemented in the future.
The main data used in all papers of this dissertation come from the Thailand – Vietnam Socio-Economic Panel (TVSEP). The first paper of this dissertation answers how improvements in rural infrastructure and income contribute to the enhancement of rural households’ resilience in the context of shocks. The second paper investigates whether non-farm employment opportunities can reduce the exploitation of natural extraction and poverty in rural areas. The results show that the development of rural infrastructure under the NRD program can help increase rural households’ absorptive and adaptive capacities against shocks and reduce poverty in absolute, relative, and multidimensional terms. Better rural infrastructure also helps provide better non-farm employment opportunities which contribute to the reduction of natural resource extraction and poverty. The third and fourth paper focus on potential policy improvements which can jointly increase rural households’ income and stimulate structural change in rural areas. The results indicate that interventions in facilitating land consolidation and promoting agricultural commercialization can stimulate structural change and reduce poverty and inequality. The fifth and sixth paper point out that rural investments can place more emphasis on ensuring year-round irrigation and improving infrastructure for information and communication technology (ICT) (i.e., the internet connectivity). These improvements can help increase welfare and reduce poverty among people in rural areas and disadvantaged groups such as female migrants.
In addition to contributing to the literature in terms of empirical evidence, this dissertation also contributes to the literature in two methodological aspects. First, this study addresses the simultaneity of (i) non-farm income and income from natural extraction in the second paper, (ii) farming efficiency and participation in land consolidation in the third paper, and (iii) crop commercialization and mechanization in the fourth paper. Second, this study accounts for selection bias, unobservable factors, endogeneity concerns in all of papers by using panel data and appropriate econometric approaches.
Based on the empirical evidence on how household capital and village conditions, especially infrastructure development, can improve rural household resilience capacities, increase income, mitigate the effects of shocks, reduce poverty, and ultimately promote structural change in Vietnam and Southeast Asia in general, several policy implications are proposed to promote structural transformation
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