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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.
11

A misericórdia que ultrapassa fronteiras: uma leitura sociológica da parábola do Bom Samaritano - Lucas 10.25-37

Tiago Samuel Lopes de Carvalho 11 October 2013 (has links)
A língua não é apenas um meio através do qual o ser humano expressa seu pensamento. Também não é apenas um código virtual já pronto e disponível fora do contexto de formação. Qualquer uma dessas compreensões desconsidera, a seu próprio modo, os falantes e situações de uso como determinantes dos fatos e regras da língua. A língua é essencialmente dialógica e deve ser compreendida enquanto forma ou processo de inter-ação, no qual os usuários interagem enquanto sujeitos sociais. Ela não é trabalho de um indivíduo, mas trabalho social e histórico seu e dos outros. E é para os outros e com os outros que ela se constitui. Por isso, se afirma que as interações ocorrem no interior de um enorme contexto social, histórico e ideológico e, nesses limites, a linguagem sofre interferências. Essa concepção exige uma leitura diferenciada do texto bíblico, ou seja, uma abordagem que alcance o aspecto histórico, social e dialógico do texto. Dessa maneira, o que se propõe é a leitura bíblica por meio do método sociológico, a leitura dos quatro lados. Esse método parte do pressuposto de que existem quatro lados ou aspectos que são determinantes na vida social de um povo. É uma metodologia orientada para uma leitura simplificada, com fins didáticos, que apresenta a totalidade do dinamismo social em quatro grandes aspectos ou dimensões da realidade social, a saber: econômico, social, político e ideológico. Fundamentado na concepção dialógica do texto, na teoria dos gêneros, no aspecto histórico-cultural com dados obtidos através de uma análise exegética e, especialmente, no aspecto sociológico da parábola do bom samaritano, este trabalho realiza uma leitura sociológica do texto de Lucas 10.2537 para alcançar o propósito da parábola do Bom Samaritano. Com essa leitura se identificaram várias vozes sociais que permeiam o texto e, também, uma proposta peculiar de modelo cristão que procura o sujeito do amor cristão em vez de se preocupar com o objeto e o limite dessa compaixão. / Language is not only a means through which human beings express their thought. It also is not simply a virtual code ready and available outside of the formation context. Any one of these comprehensions, each in its own way, does not consider the speakers and the situations of use as determiners of the facts and rules of the language. Language is essentially dialogic and should be understood as a form or process of inter-action, in which the users interact as social subjects. It is not the work of one individual, but the social and historical work of that individual and of others. And it is constituted for the others and with the others. That is why it is affirmed that the interactions occur within an enormous social, historical and ideological context and, in these limits, language suffers interferences. This concept demands a differentiated reading of the biblical text, that is, an approach which takes in the historical, social and dialogic aspect of the text. Thus, what is being proposed is a biblical reading through the sociological method, a reading from the four sides. This method is based on the presupposition that there exist four sides or aspects which determine the social life of a people. It is a methodology orientated toward a simplified reading with didactic goals, which presents the totality of the social dynamism in four great aspects or dimensions of the social reality, that is: economic, social, political and ideological. Based on the dialogic concept of the text, on the theory of genres, on the historical-cultural aspect with data obtained from an exegetical analysis and, especially, on the sociological aspect of the parable of the Good Samaritan, this paper carries out a sociological reading of the text of Luke 10:25-37 to reach the goal of the parable of the Good Samaritan. With this reading various social voices were identified which permeate the text as was also identified a peculiar proposal of a Christian model which seeks the protagonist of the Christian love instead of being concerned with the object and the limit of this compassion.
12

兩岸都市更新政策方法比較研究 / Comparative researches on policies and methods of urban renewal between Taiwan and mainland China

鄭巍 Unknown Date (has links)
20世紀初期,以新城建設為特徵的發展形式對大陸地區的農地資源造成極大破壞,在經歷了「空間大躍進」的失敗之後,都市更新成為大陸地區新時期城市建設的的重點方向。台灣地區之都市更新事業早在日治時期就已起步,1998年《都市更新條例》頒布以來已具備完善的制度架構以及豐富的實施經驗。在相似的文化背景之下,作為都市更新的先行者,台灣地區是否能夠給尚處於起步階段的大陸地區提供借鏡意義,大陸地區又能否後來居上為台灣地區的都更困境提供良方?這便是本研究所要探討的課題。 本研究從法令政策及實施效果兩個面向切入,以制度面與執行面對兩岸之都市更新政策與方法進行比較分析。法令政策方面,通過台灣地區都市更新制度以及大陸地區土地產權制度變遷過程之梳理,釐清當前兩岸都市更新的基本流程。本研究認為兩岸都更流程雖然在某些細節存在差別,但總體來說仍十分相似。實施效果方面,本研究選取台北市、上海市以及深圳市三個城市之案例進行分析。在相似的都市更新流程下,兩岸在具體案例的實施過程則表現出政府角色的差異,形成了台灣地區民間主導更新、大陸地區政府主導更新的局面,而這也是兩岸都市更新的主要差異。 本研究認為,土地產權制度的差異是造成兩岸都市更新中政府角色不同的主要原因。換言之,台灣地區土地私有制使得民間成為都市更新的主導者;相對地,大陸地區土地公有制下的土地財政則使得地方政府主導了都市更新。在產權差異的大背景下,兩岸都更在操作方法上並無足夠的相互借鏡意義,因此本研究僅從更新理念上對兩岸之都更事業提出了一定的建議。
13

Det idealistiska nöjet : Användaracceptans av mobiler med sidoböjning

Granberg, Timothy January 2016 (has links)
Mobiltelefoner har utvecklats i snabb takt över åren, från ett nytt koncept till en vardaglig självklarhet för många i bägge personlig och professional fattning. Efter smartphonens myntning i 1994 med IBM Simon Personal Communicator har mobiltelefonen evolveras i många olika riktningar. 2013 kom den först smartphonen med välvd skärm, Samsung Galaxy Round, vilket påbörjande en ny trend av böjda smartphones. Denna studie undersöker användaracceptans av den senaste typen av välvd skärm, sidoböjning, utifrån ett perspektiv av mänskliga nöjen. Studien föreslår att innovationen av sidoböjning inte avnjuts pragmatiskt utan idealistiskt, med fokus på adoptörens ideologiska och sociala begär. Innovationens framtid och utspridning utöver samhället slutdras som osäkert, med förslag på framtida forskning att vidareutveckla ämnets kunskapsbas. / Mobile phones have developed rapidly over the years, from a novel concept to an typical day certainty for many in both personal and professional use. Following the advent of the smartphone in 1994 with the IBM Simon Personal Comunicator, the mobile phone has evolved in a number of directions. In 2013, the Samsung Galaxy Round was launched, the first smartphone featuring a curved display, sparking a new trend of curved-display smartphones. This study investigates the user acceptance of the latest type of curved displays, curved sides, from a perspective of human pleasures. The studie suggests the innovation of curved sides is not enjoyed pragmatically, but idealistically, with a focus on the adopter’s ideological and social desires. The future of the innovation and its diffusion throughout society is concluded to be uncertain, with suggestions of future research to further develop the subject’s base of knowledge.
14

On parabolic stochastic integro-differential equations : existence, regularity and numerics

Leahy, James-Michael January 2015 (has links)
In this thesis, we study the existence, uniqueness, and regularity of systems of degenerate linear stochastic integro-differential equations (SIDEs) of parabolic type with adapted coefficients in the whole space. We also investigate explicit and implicit finite difference schemes for SIDEs with non-degenerate diffusion. The class of equations we consider arise in non-linear filtering of semimartingales with jumps. In Chapter 2, we derive moment estimates and a strong limit theorem for space inverses of stochastic flows generated by Lévy driven stochastic differential equations (SDEs) with adapted coefficients in weighted Hölder norms using the Sobolev embedding theorem and the change of variable formula. As an application of some basic properties of flows of Weiner driven SDEs, we prove the existence and uniqueness of classical solutions of linear parabolic second order stochastic partial differential equations (SPDEs) by partitioning the time interval and passing to the limit. The methods we use allow us to improve on previously known results in the continuous case and to derive new ones in the jump case. Chapter 3 is dedicated to the proof of existence and uniqueness of classical solutions of degenerate SIDEs using the method of stochastic characteristics. More precisely, we use Feynman-Kac transformations, conditioning, and the interlacing of space inverses of stochastic flows generated by SDEs with jumps to construct solutions. In Chapter 4, we prove the existence and uniqueness of solutions of degenerate linear stochastic evolution equations driven by jump processes in a Hilbert scale using the variational framework of stochastic evolution equations and the method of vanishing viscosity. As an application, we establish the existence and uniqueness of solutions of degenerate linear stochastic integro-differential equations in the L2-Sobolev scale. Finite difference schemes for non-degenerate SIDEs are considered in Chapter 5. Specifically, we study the rate of convergence of an explicit and an implicit-explicit finite difference scheme for linear SIDEs and show that the rate is of order one in space and order one-half in time.
15

On the Solution Phase of Direct Methods for Sparse Linear Systems with Multiple Sparse Right-hand Sides / De la phase de résolution des méthodes directes pour systèmes linéaires creux avec multiples seconds membres creux

Moreau, Gilles 10 December 2018 (has links)
Cette thèse se concentre sur la résolution de systèmes linéaires creux dans le contexte d’applications massivement parallèles. Ce type de problèmes s’exprime sous la forme AX=B, où A est une matrice creuse d’ordre n x n, i.e. qui possède un nombre d’entrées nulles suffisamment élevé pour pouvoir être exploité, et B et X sont respectivement la matrice de seconds membres et la matrice de solution de taille n x nrhs. Cette résolution par des méthodes dites directes est effectuée grâce à une étape de factorisation qui réduit A en deux matrices triangulaires inférieure et supérieure L et U, suivie de deux résolutions triangulaires pour calculer la solution.Nous nous intéressons à ces résolutions avec une attention particulière apportée à la première, LY=B. Dans beaucoup d’applications, B possède un grand nombre de colonnes (nrhs >> 1) transformant la phase de résolution en un goulot d’étranglement. Elle possède souvent aussi une structure creuse, donnant l’opportunité de réduire la complexité de cette étape.Cette étude aborde sous des angles complémentaires la résolution triangulaire de systèmes linéaires avec seconds membres multiples et creux. Nous étudions dans un premier temps la complexité asymptotique de cette étape dans différents contextes (2D, 3D, facteurs compressés ou non). Nous considérons ensuite l’exploitation de cette structure et présentons de nouvelles approches s’appuyant sur une modélisation du problème par des graphes qui permettent d’atteindre efficacement le nombre minimal d’opérations. Enfin, nous donnons une interprétation concrète de son exploitation sur une application d’électromagnétisme pour la géophysique. Nous adaptons aussi des algorithmes parallèles aux spécificités de la phase de résolution.Nous concluons en combinant l'ensemble des résultats précédents et en discutant des perspectives de ce travail. / We consider direct methods to solve sparse linear systems AX = B, where A is a sparse matrix of size n x n with a symmetric structure and X and B are respectively the solution and right-hand side matrices of size n x nrhs. A is usually factorized and decomposed in the form LU, where L and U are respectively a lower and an upper triangular matrix. Then, the solve phase is applied through two triangular resolutions, named respectively the forward and backward substitutions.For some applications, the very large number of right-hand sides (RHS) in B, nrhs >> 1, makes the solve phase the computational bottleneck. However, B is often sparse and its structure exhibits specific characteristics that may be efficiently exploited to reduce this cost. We propose in this thesis to study the impact of the exploitation of this structural sparsity during the solve phase going through its theoretical aspects down to its actual implications on real-life applications.First, we investigate the asymptotic complexity, in the big-O sense, of the forward substitution when exploiting the RHS sparsity in order to assess its efficiency when increasing the problem size. In particular, we study on 2D and 3D regular problems the asymptotic complexity both for traditional full-rank unstructured solvers and for the case when low-rank approximation is exploited. Next, we extend state-of-the-art algorithms on the exploitation of RHS sparsity, and also propose an original approach converging toward the optimal number of operations while preserving performance. Finally, we show the impact of the exploitation of sparsity in a real-life electromagnetism application in geophysics that requires the solution of sparse systems of linear equations with a large number of sparse right-hand sides. We also adapt the parallel algorithms that were designed for the factorization to solve-oriented algorithms.We validate and combine the previous improvements using the parallel solver MUMPS, conclude on the contributions of this thesis and give some perspectives.
16

Nouvelles configurations d'interaction pour l'optimisation conjointe des performances des composants acouto-optiques / New configurations of interaction for simultaneous optimization of the acousto-optic devices

Dieulangard, Anthony 11 December 2014 (has links)
Une description des différentes configurations d’interaction ayant lieu dans les matériaux usuellement employés dans le domaine acousto-optique est proposée. Un exemple d’application illustre les caractéristiques déterminantes propres à chaque fonction que permet l’interaction acousto-optique, à savoir la modulation, la déviation, le décalage en fréquence et le filtrage d’un faisceau optique. Cette thèse est plus particulièrement consacrée aux interactions acousto-optiques anisotropes dans le cristal de Paratellurite, matériau majoritairement employé pour les applications de déflexion et de filtrage de par ses qualités photo-élastiques remarquables et son large domaine de transparence optique. Ces propriétés optiques, acoustiques et acousto-optiques sont décrites en détail. Nous nous intéressons plus particulièrement aux caractéristiques de l’interaction NPM (Narrow Phase Mismatch) et TPM (Tangent Phase Mismatch), respectivement employées pour le filtrage et la déflexion. Ceci nous conduit à l’étude de la bande passante spectrale d’un déflecteur et de sa potentielle application en tant que réseau de diffraction à bande passante et périodicité spatiale modulable. Ensuite nous proposons la mise en cascade d’un déflecteur et d’un filtre dans le but de concevoir un décaleur de fréquence variable à faible décalage. Enfin, nous proposons une configuration originale pour répondre aux contraintes d’utilisation rencontrées avec l’interaction NPM pour les applications de filtrage. La conception et la réalisation d’un composant multiélectrodes à interaction double est alors présentée dans la gamme spectrale [400; 650 nm]. La configuration proposée permet à la fois de réduire de 50% l’intensité des lobes secondaires tout en homogénéisant la bande passante optique du filtre sur sa bande spectrale de travail. / The different configurations of acousto-optic interactions taking place in usual employed materials are presented. For each function (modulation, deflection, shifting and filtering), an exemple of application highlights the decisive characteristics of the component. This thesis is particularly devoted to the anisotropic interactions occuring in Paratellurite crystal. Such material is widely used for filtering and deflection applications due to its high figure of merit and also for its large optical transparency domain, from Ultra-Violet to Infra-Red. Optical, acoustical and acoustooptical properties of Paratellurite cristal are detailed. More precisely, we are interested in anisotropic interactions, in particular NPM (Narrow Phase Mismatch) and TPM (Tangent Phase Mismatch), respectively employed for Acousto-Optic Tunable Filters (AOTF) and Acousto-Optic Deflectors (AOD). This leads to the study of the optical bandwidth of a deflector with a potential application as a tunable transmissive grating beam splitter for multiple laser line separation. Then, we propose to cascade an AOTF with an AOD in order to get a wide bandwidth tunable optical low frequency shifter. Finally, we present the design and fabrication of a multi-transducer component based on dual anisotropic interaction in the visble spectral range, from 400 to 650 nm. A significative reduction of sides lobes is observed (-50%) with an homogenisation of the optical bandwidth of the filter on its spectral working range.
17

Swot-modellen : modellen, dess användning och användbarhet för framgångsrika företag i regionen

Saillard, Joachim January 2012 (has links)
Sammanfattning Titel:                                   Swot-modellen – Modellen, dess användning och användbarhet för framgångsrika företag i regionen   Nivå:                                  C-uppsats i ämnet företagsekonomi   Författare:                         Joachim Saillard   Handledare:                       Lars Torsten Eriksson   Datum:                               2012-07-16   Bakgrund:                          Swot-modellen ger en struktur för beskrivning och analys av en organisations starka samt svaga sidor, dess externa hot och möjligheter. Modellen har funnits i cirka 50 år och nått stor spridning. Vad har forskningen om swot-modellen hittills kommit fram till? Hur ser små- och medelstora företag i Gävleregionen på modellen i sina praktiker?   Syfte:                                  Syftet med uppsatsen är att göra en state-of-the-art genomgång av forskningen om swot-modellen samt visa hur en grupp regionala små- och medelstora företag använder modellen samt kritiskt testa Framför-databasens potential som empiriskt material. Avsikten är att lägga en grund samt skapa en utgångspunkt för fortsatt forskning om modellen som verktyg för företagsutveckling i den regionala miljön.                                             Metod:                                Studien bygger på en genomgång av ett stort antal forskningsartiklar om swot-modellen. De flesta artiklar analyserar enskilda aspekter av modellen, medan några visar sig ge en översikt över olika modellstudier. Eftersom det visar sig att ytterst få studier redovisar empiriska data om modellens användning och fortsatta empiriska studier behövs, har en genomgång också gjorts av swot-kommentarer i en databas för regionala företag – det så kallade Framför-projektet som drivs av bland annat Svenskt Näringsliv, Aktiv Revision och kommunerna i Gästrikland. I databasen finns registrerade data för små- och medelstora företag, åren 2002-2012. Databasen bygger på standardiserade intervjuer där svar registrerats om swot-data. Baserade på dessa har en sekundäranalys gjorts och den empiriska genomgången har behandlats som en pilotstudie om företags beskrivning av interna faktorer.   Resultat & slutsatser:       Studien ger en analys av forskningen om swot-modellen. Den visar att antalet teoretiska studier om swot-modellen ökat, medan få empiriska studier gjorts. Den empiriska delen visar att företagen i regel är väl förtrogna med modellen, men inte alltid har aktuella värden för dess huvudkategorier. Den aktuella databasen behöver förstärkas och modellen ges en bättre koppling till aktiv implementering.    Förslag till fortsatt forskning:                           Fortsatta studier behövs om företagens strategiska beslutssituationer utifrån swot-modellen som utvärderingsverktyg, och möjligen andra kompletterande teorier/modeller.   Uppsatsens bidrag:            Studien ger en överblick över den hittillsvarande forskningen om swot-modellen, dess användning och användbarhet för olika organisationer. Eftersom förvånansvärt få empiriska studier hittills gjorts kan uppsatsens empiriska studie ses som ett särskilt forskningsbidrag.   Nyckelord:                         Swot, företag, interna faktorer det vill säga starka och svaga sidor, strategisk planering, Framför-databasen, swot-modellens dualperspektiv. / Abstract Title:                                   The swot model – the model, its usage and usefulness for successful firms in the region   Level:                                 Final assignment for Bachelor Degree in Business Administration   Author:                               Joachim Saillard   Supervisor:                        Lars Torsten Eriksson   Date:                                  2012-07-16   Background:                      The swot-model provides a structure for description and analysis of an organizations strong and weak sides, its opportunities and threats. The model has existed approximately 50 years and has attained a big spread. What has the present research on swot concluded? How do small- and medium sized firms in the region of Gävle treat the model in their practices?   Aim:                                    The aim of the thesis is to do a state-of-the-art review on the research concerning the swot-model, and to show how a group of regional small- and medium sized firms use the model as well as to conduct a critical examination of the Framför-databases potential as empirical substance. The intention is to form a basis and starting point for future research, regarding to the model as a tool for business development in the regional environment.   Method:                             The study is founded on a review of a big number of research papers about the swot-model. Most of them analyze certain aspects of the model, while others seem to give a summary over different model studies. Since there has been shown to be exceedingly few studies who account for empirical data about the models use and further empirical studies is needed, a review of a database containing swot-comments – the so called Framför-project which is run by the Federation of Swedish Enterprise, Aktiv Revision and the municipalities in Gästrikland, has also been carried out. In the database there are registered data for small- and medium sized firms between the years 2002-2012. The database builds on standardized interviews of which swot-data have been registered. Based on this, secondary analysis has been carried out and the empirical review has been attended as a pilot study about firms’ descriptions of their internal factors.   Result & Conclusions:      The study provides an analyze on research concering the swot-model. It shows that the number of theoretical studies about the swot-model has increased, while few empirical studies have been carried out. The empirical part of the study shows that the firms generally are well familiar with the model, but that they don’t always have current values for its main categories. The current database needs to be strengthened and the model given a better connection to active realization.   Suggestions for future research:                 Future research is needed about the firms strategic decision situations with the swot-model as an evaluation tool as starting point, and possibly other complementing theories/models.   Contribution of the thesis:                          The thesis provides an overview over the research up until now concerning the swot-model, its use and usefulness for different organizations. Since surprisingly few present empirical studies have been carried out, the empirical study that the thesis provides can be seen as a particular research contribution.    Key words:                         Swot, firms, internal factors i.e. strong and weak sides, strategic planning, the Framför-database, swot-model dual perspective.
18

相同會計師查核關係人交易雙方對負債資金成本之影響 / The Effect of Same Auditor Auditing Both Sides of Related Party Transactions on Cost of Debt

賴彥均 Unknown Date (has links)
本研究係探討關係人交易雙方是否委任相同會計師進行查核,對企業負債資金成本之效果。本文以企業利息費用除以平均帶息負債衡量企業之負債資金成本,企業之關係人交易部分則分成關係人銷貨交易、關係人進貨交易、關係人應收款、關係人應付款等四類型交易,來討論關係人交易與企業負債資金成本之關聯,接著將各類型關係人交易再細分成由相同會計師查核關係人交易雙方與由不同會計師查核關係人交易雙方兩類,以檢驗相同會計師查核對於企業負債資金成本之影響。 研究結果發現關係人交易與企業負債資金成本之關聯並無統計上之顯著性。然將關係人交易進一步拆分為是否由相同會計師查核關係人交易雙方後,關係人進貨交易與關係人銷貨交易等兩類型交易若由相同會計師查核交易雙方,其相較於不同會計師查核能夠有效減緩企業負債資金成本增加之情形。 / This study examines the effect of same auditor auditing both sides of related party transactions (RPTs) on cost of debt. In this study, cost of debt is measured using interest expenses divided by average interest bearing debt and we hand collect from annual reports the data of the four common types of RPTs: sales to related parties, purchases from related parties, accounts receivable from related parties and accounts payable to related parties. For the four types, we further split RPTs into RPTs whose involved sides are audited by the same auditor and RPTs whose involved sides are audited by different auditors. We do not find any evidence that RPTs are associated with cost of debt. However, we find that for sales to related parties and purchases from related parties, RPTs whose involved sides are audited by the same auditor are associated with cost of debt less strongly than RPTs whose involved sides are audited by different auditors. Our results suggest that same auditor auditing can mitigated the detrimental effect of RPTs on cost of debt.
19

Spolupráce školy a rodiny jako základ fungujícího partnerství / Cooperation between school and family as the foundation of efektive partnership

Slivoňová, Alena January 2016 (has links)
The thesis deals with the theoretical part to highlight the importance of cooperation between schools and families in terms of children, from the perspective of families and teachers and schools. Furthermore, the work deals with a survey to improve relations between the school and parents in our elementary school. Determines whether the five years that we establish a closer cooperation with parents to improve the perception of the school community and neighborhood residents. The work focuses on empirical research of events for parents, cooperation, but also obstacles that may arise. KEYWORDS: Cooperation and partnership schools and the child's family, trust between the two sides, the benefits of cooperation, forms of cooperation, the relationship between parents and school teachers, in collaboration barriers, parents welcome the involvement of parents in the joint actions.
20

Politiques migratoires optimales, doubles frontières et bien-être social dans les modèles à générations imbriquées / Optimal migration policies, two-sided borders and social welfare in overlapping generations models

Chaabane Bouzid, Inaam 14 December 2015 (has links)
Après une introduction générale et un survol de littérature, l’apport de cette thèse est que chaque gouvernement choisit pour son pays le flux de migrants qui maximise le bien-être social. Il s’ensuit naturellement l’introduction du concept de double frontière optimale. Dans un modèle OLG simple à la Galor (1986) avec 2 périodes, 2 pays et offre de travail exogène, le chapitre 2 étudie le rôle des différences d’épargne entre les pays sur l’équilibre stationnaire. Le planificateur social choisit le taux de migration qui conduit l’économie à la Règle d’Or (que les frontières soient coûteuses ou non). Si un pays laisse entrer alors l’autre laisse sortir, mais les taux de migration diffèrent à l’optimum social. Un planificateur mondial choisirait comme les individus. Le chapitre 3 développe un modèle OLG à 3 périodes et 2 pays. En 1ere période les jeunes s’éduquent avec des taux de rendement différent selon le pays, en seconde et troisième période ils offrent du travail endogène. Le taux de migration conduit chaque pays à l’optimum social et est tel qu’un des deux pays souhaite fermer ses frontières avant l’autre. Ces asymétries génèrent des incitations à la migration illégale, et par conséquent les salaires et taux d’intérêt ne s’égalisent pas à l’équilibre post-migratoire.Le chapitre 4 étend le précédent au cas où seuls les adultes sont autorisés à migrer et ajoute un système de retraite. Les pays receveurs souhaiteraient accueillir plus de migrants que les pays d’envois ne souhaiteraient en laisser partir. Le choix individuel de migration repose davantage sur un choix d’éducation des enfants que sur le choix de bénéficier d’une retraite. Ce résultat contredit la littérature sur ce point. / After a general introduction and a literature review, in a 2-country OLG model, this thesis considers a non yet studied case where each government chooses for his country theflow of migrants that maximizes the post-migration social welfare. Since decision flows are unilateral, it naturally follows the introduction of the concept of optimal two-sided-borders. In a simple OLG model à la Galor (1986) with 2 periods, 2 countries and an exogenous labor supply, Chapter 2 examines the differences in optimal migration flows when countrydiffers in time preferences. With or without costly borders, optimal flows that lead the economy to the Golden Rule differ, so that one country closes its borders before the otherone. A world social planner would make an opposite migration policy compared with the country-specific social planner. Chapter 3 develops an OLG model where young train and get the return to education next period, adult and old endogenously work. The optimal migration rates leading to the social optimum of each country differ. These asymmetries generate incentives for illegal migration, hence wages and interest rates do not equalize in the post-migration equilibrium. Chapter 4 extends the previous by introducing a pension system. If by the law, only adults are allowed to migrate, then the receiving country want to attract more migrants than the departure country would let go. The individual choice of migration depends more on the children education than on the retirement benefit choice. This result is not in line with the existing literature. The Welfare State is not the first reason for which migrants leave their country.

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