A hierarchical control system is proposed for automated flexible manufacturing cells (FMC) that operate in a job shop flow setting. The control system is made up of a higher level scheduler/reactive scheduler, which optimizes the production flow within the cell, and a lower level supervisor that implements the decisions of the scheduler on the shop floor. Previous studies have regularly considered the production scheduling and the supervisory control as two separate problems. This has led to: i) deadlock-prone optimized schedules that cannot be implemented in an automated setting, ii) deadlock-free optimized schedules that lack the means to be transformed into shop floor supervisors, or iii) supervisors that can safely drive the system with no consideration for production performance. The proposed control system combines mathematical models and an insertion heuristic to solve the deadlock-free scheduling problem in job shops, a deadlock-free reactive scheduling heuristic that can revise the schedules upon the occurrence of a wide variety of disruptions, and a systematic procedure that can transform schedules into readily implementable Petri net (PN) supervisors. The integration of these modules into one control hierarchy guarantees a correct, optimized and agile behavior of the controlled system. The performances of the mathematical models, the scheduling and the reactive scheduling heuristics were evaluated by comparison to performances of previous approaches. Experimental results showed that the proposed modules performed consistently better than the other corresponding approaches. The supervisor realization procedure and the overall control architecture were validated by simulation and implementation in an experimental robotic FMC. The control system developed was capable of driving the experimental cell to satisfactorily complete the processing of different product mixes that featured complex processing routes through the cell.

A hierarchical control system is proposed for automated flexible manufacturing cells (FMC) that operate in a job shop flow setting. The control system is made up of a higher level scheduler/reactive scheduler, which optimizes the production flow within the cell, and a lower level supervisor that implements the decisions of the scheduler on the shop floor. Previous studies have regularly considered the production scheduling and the supervisory control as two separate problems. This has led to: i) deadlock-prone optimized schedules that cannot be implemented in an automated setting, ii) deadlock-free optimized schedules that lack the means to be transformed into shop floor supervisors, or iii) supervisors that can safely drive the system with no consideration for production performance. The proposed control system combines mathematical models and an insertion heuristic to solve the deadlock-free scheduling problem in job shops, a deadlock-free reactive scheduling heuristic that can revise the schedules upon the occurrence of a wide variety of disruptions, and a systematic procedure that can transform schedules into readily implementable Petri net (PN) supervisors. The integration of these modules into one control hierarchy guarantees a correct, optimized and agile behavior of the controlled system. The performances of the mathematical models, the scheduling and the reactive scheduling heuristics were evaluated by comparison to performances of previous approaches. Experimental results showed that the proposed modules performed consistently better than the other corresponding approaches. The supervisor realization procedure and the overall control architecture were validated by simulation and implementation in an experimental robotic FMC. The control system developed was capable of driving the experimental cell to satisfactorily complete the processing of different product mixes that featured complex processing routes through the cell.

When a child for some reason can’t live with their parents it is up to the welfare system to provide a home and care for that child. In Sweden long-term foster care placements are the most common state interventions for those children. Recent studies have shown that as much as one out of four foster care placements break down in the child’s adolescent years. To experience one or a series of tough separations from important elders has shown to have negative effects on the development of the child. This does not align with the welfare systems’  responsibility to always act in favor of the child. Always acting in favor of the Child is at the core of the Convention on the rights of the Child. In the following qualitative content analysis five state documents (three from the National Board of Health and Welfare, one from The Ombudsman for Children and one governmental investigation document) have been examined. The aim of the analysis is to examine how the documents portray placement breakdowns in foster care and how much they focus on the child rights perspective in their portrayals. Previous research and two theories regarding children are used as the theoretical framework to help analyze the essay results. The two theories are Bronfenbrenner's ecological system theory of child development and the theory of childhood sociology with emphasis on children as actors. This essay comes to the conclusion that the state documents are well informed of the complex nature of placement breakdowns and the dissonance between the problem of breakdowns and the child’s right perspective. The documents also contain a number of interventions that in theory could reduce the number of breakdowns. What is revealed is that the process of acknowledging the problem, finding a solution and implementing it in the social care practice takes a lot of time and is a slow process. The discussion includes that further research of what can be done on a municipal level would be of use.

Placering i familjehem är en vanlig insats när barn och unga inte bedöms kunna få sina behov tillgodosedda i sin ursprungsfamilj, de utgör i Sverige majoriteten av placeringar i samhällsvård. De barn som blir placerade i familjehem för stadigvarande vård och fostran har rätt till en stabil och trygg vård. Trots detta sker sammanbrott vilket kan försätta barnen i ytterligare en utsatt situation. Syftet med denna kvalitativa studie har varit att undersöka socialarbetares tankar om och arbete för att förebygga sammanbrott hos barn som är placerade i familjehem. Frågeställningar i studien har varit: Vilka är orsakerna till att sammanbrott sker? Vilka former av adekvat stöd minskar risken för sammanbrott?I studien genomfördes fem intervjuer med socialsekreterare i två medelstora kommuner i Stockholm. I analysen framkom tre huvudteman;  Matchning, det vill säga hur väl, samt vilka förutsättningar det finns att matcha det placerade barnet med det tilltänkta familjehemmet.  Sammanbrott och omplacering, med det menas att barnet behöver flytta till en ny placering innan att vådbehovet uppfyllts. Nätverkshem, de hem som tar emot barn som de känt sen tidigare, dessa kan vara vänner till familjen eller släktingar.  Den analyserade empirin har sedan tolkats med hjälp av systemteori och tidigare forskning. I studien framgår att den främsta orsaken till sammanbrott är en bristfällig matchning mellan barn och familjehem. Det framkom även att placering av ett barn behöver göras med ett helhetsperspektiv där matchningsprocessen innefattar rätt skolform, ett familjehem som har förstått uppdraget samt rätt stöd från socialsekreterarna. Helhetsperspektivet jämförs i studien med det systemteoretiska synsättet. I studien framgår även att socialsekreterarna på familjehemsenheten inte är huvudansvariga när det kommer till att matcha familjehem och barn utan att det snarare är handläggare på utredningsenheten samt familjehemsrekryterare i samråd med sina chefer som sköter matchningsprocessen. Utredningsenheten är den enhet där barnet och familjens behov först kartläggs. De kan även besluta om andra stödinsatser, exempelvis familjebehandling, kontaktperson etc. Vid de fall ett barn inte bedöms kunna få sina behov tillgodosedda i det egna hemmet fattas beslut om placering i jourhem alternativt familjehem. När barnet placeras i familjehem är tanken att det ska vara en långvarig placering då bedömningen är att det krävs mer jobb i familjen innan barnet kan flytta hem. Oftast är målet en hemflytt till ursprungsfamiljen, det vill säga den biologiska familjen. När barnet blir familjehemsplacerat är det socialsekreterarna (barnhandläggare och familjehemssekreterare) på familjehemsenheten som tar över ansvaret för placeringen. Det framkommer att relationen mellan, handläggare på utredningsenheten och handläggare på familjehemsenheten är kortvarig, de samverkar enbart under överlämningen av ärendet. / Placement in foster care is a common intervention when children and young people are not able to have their needs met in their biological family. Foster homes are the most frequent form of placements in community care in Sweden. Children who are placed in a foster home for permanent care and upbringing have the right to a stable and safe care. Despite this, breakdowns occur, which can put the children in another vulnerable situation. The purpose of this qualitative study has been to investigate how social workers work to prevent breakdowns in the care of children that are placed in foster homes. Questions in the study have been: What are the reasons why breakdowns occur? What forms of adequate support reduce the risk of breakdown? In the study, five interviews were conducted with social workers in two medium-sized municipalities in Stockholm. In the analysis, three main themes emerged:  Matching, namely, how well the social workers can match the child with the foster care homes.  Breakdowns and relocations, when the child has to move before the care needs are fulfilled Network homes, the foster homes that care for someone that they know, it can be the child of a friend or a relative. The analyzed empirical evidence has then been interpreted with the help of systems theory and previous research. The study shows that the main causes of breakdowns are a poor match between children and foster homes. It also emerged that placement of a child needs to be done with a holistic perspective where the matching process includes the right type of school, a foster home that understands the mission and the right support from the social workers. In the study, the holistic perspective is synonymous with general systems theory. The study also shows that the social workers in the family home unit are not primarily responsible when it comes to matching family homes and children, it is rather the investigation unit and foster home recruiters in consultation with their managers. The investigation unit is the unit that charts the families and the children's needs. They can also make decisions regarding if the family need other support efforts, such as contact persons or family treatments. If the family is assessed that the other support efforts are not sufficient, they can decide to put the family in foster care. If the foster care is assessed to take longer time the matter gets transferred to the family unit. In cases where a child is judged not to be able to have their needs met in their own home, a decision is made to place them in an emergency home or a family home. When the child is placed in a family home, the idea is that it should be a long-term placement, as the assessment is that more work is required in the family before the child can move home. Most often, the goal is a move home to the family of origin, namely the biological family. When the child is placed in a family home, it is the social workers (child caseworkers and family home secretary) at the family home unit who take over responsibility for the placement.

No description available.

This dissertation deals with court-executive relations in post-authoritarian Argentina (1983-2006). Specifically, I analyse Supreme Court behaviour in highly sensitive cases to determine whether the tribunal has cooperated with or obstructed the government’s policy preferences in three key policy areas: human rights, economic emergency and pensions. This innovative type of approach – i.e., focusing on a small number of highly sensitive decisions – allows me to concentrate on cases that are genuinely important for the government or, more precisely, for the country’s political administration. There are cases that are significant for the State apparatus but irrelevant for the president (thinking of politicians as self-interested actors). My research uses a rational choice approach to courts, underscoring the strategic nature of judicial behaviour. This vision of judges provides a more accurate account of judicial-executive relations by bringing politics into the study of courts. By focusing exclusively on attitudes and apolitical jurisprudence, other visions take for granted the institutional context. Political stability, for example, cannot be assumed in many developing democracies. My findings indicate that the Argentine Supreme Court has consistently avoided obstructing the president’s policy preferences. Such behaviour is motivated by strategic considerations: judges are risk-averse actors that avoid clashing with the executive. For most of the time, the Supreme Court has operated under unified government, which increases the chances of being punished for anti-government decisions. Two other factors also account for the court’s risk-averse behaviour. First, procedural rules grant the Supreme Court wide discretion over its docket. The tribunal has used such discretion to strategically select the timing of its decisions. Second, recurrent democratic breakdowns have repeatedly led to attacks against the court, such as impeachment, irregular dismissals, and/or enlargements. Third, politicians exert broad control of judicial promotions, allowing them to block the careers of independent, courageous judges that act as a check on political power.

Ce mémoire de thèse s'inscrit dans le cadre du programme « avion plus électrique », il comprend deux parties.La première est consacrée à la présentation détaillée du contexte, c'est-à-dire du processus qui conduit à électrifier la plupart des systèmes présents dans l'avion, un exemple d'actionneur électromécanique spécifique, conçu dans ce cadre sera aussi détaillé notamment pour ce qui concerne son mode d'alimentation. La seconde partie, plus longue, est consacrée à différents processus de fiabilisation de structures d'électroniques de puissance. Du fait de l'électrification croissante de l'avion, ces structures vont se multiplier à bord, mais la fiabilité connue de ces dispositifs n'est pas apte à satisfaire aux exigences de l'aéronautique. Les processus de fiabilisation, dans leur majorité, sont orientés, en cas de panne, vers un isolement de la source du défaut, pour permettre un fonctionnement en mode dégradé, supporté par le système. Par ailleurs, un dispositif de sécurisation de bras d'onduleur est décrit : un sectionneur commandé à thyristors et fusible (SCTF2). Ce système permet d'isoler électriquement le bras d'onduleur victime d'un défaut au sein d'un onduleur triphasé. L'emplacement de prédilection du SCTF2 est la connexion bras d'onduleur et bus continu d'alimentation. Les simulations de ce système de fiabilisation sont menées sur PSIM. Ce mémoire propose des modélisations approchées, pour l'outil de CAO adopté, des composants IGBT et fusibles, lorsque ces derniers sont soumis à un régime de courant extrême (court-circuit). / This manuscript of thesis was written in two parts for the "More Electric Aircraft" program. The first part presents in great detail the context of the thesis that is (i.e) the processes which allow electrifying the most of classic aircraft-systems. In this part, an example of special electromechanical actuator build in the More Electric aircraft program will be presented with meticulous care, in particular its command and supply systems. The second part, more extensive, is devoted to various solutions which improve the reliability of the power-electric systems. With the growth of the electrification of the aircrafts, several solutions of this kind will be multiplicated on board, but today most of these solutions haven't the reliability intended to the aeronautical applications. For the most part, the reliability processes consist in isolating the origins of a breakdown, in order that the system can continue to work in a debased mode. In addition, a system which protects inverter's legs is described; it's a controlled circuit breaker which uses thyristors and fuses (SCTF2). This system of reliability allows electrical isolating of faulty inverter's leg in a three phase inverter. The preferential position of a SCTF2 is the connexion between inverter's leg and the DC bus. Simulations of the SCTF2 are done on PSIM software. For PSIM, this manuscript poposes some approximative modelisations of the components like IGBT and fuse when they are subjected to a dangerous high-current (short-circuit).

Les méthodes d'algèbres linéaire classiques, pour le calcul de valeurs et vecteurs propres d'une matrice, ou des approximations de rangs inférieurs (low-rank approximations) d'une solution, etc..., ne tiennent pas compte des structures de matrices. Ces dernières sont généralement détruites durant le procédé du calcul. Des méthodes alternatives préservant ces structures font l'objet d'un intérêt important par la communauté. Cette thèse constitue une contribution dans ce domaine. La décomposition SR peut être calculé via l'algorithme de Gram-Schmidt symplectique. Comme dans le cas classique, une perte d'orthogonalité peut se produire. Pour y remédier, nous avons proposé deux algorithmes RSGSi et RMSGSi qui consistent à ré-orthogonaliser deux fois les vecteurs à calculer. La perte de la J-orthogonalité s'est améliorée de manière très significative. L'étude directe de la propagation des erreurs d'arrondis dans les algorithmes de Gram-Schmidt symplectique est très difficile à effectuer. Nous avons réussi à contourner cette difficulté et donner des majorations pour la perte de la J-orthogonalité et de l'erreur de factorisation. Une autre façon de calculer la décomposition SR est basée sur les transformations de Householder symplectique. Un choix optimal a abouti à l'algorithme SROSH. Cependant, ce dernier peut être sujet à une instabilité numérique. Nous avons proposé une version modifiée nouvelle SRMSH, qui a l'avantage d'être aussi stable que possible. Une étude approfondie a été faite, présentant les différentes versions : SRMSH et SRMSH2. Dans le but de construire un algorithme SR, d'une complexité d'ordre O(n³) où 2n est la taille de la matrice, une réduction (appropriée) de la matrice à une forme condensée (J(Hessenberg forme) via des similarités adéquates, est cruciale. Cette réduction peut être effectuée via l'algorithme JHESS. Nous avons montré qu'il est possible de réduire une matrice sous la forme J-Hessenberg, en se basant exclusivement sur les transformations de Householder symplectiques. Le nouvel algorithme, appelé JHSJ, est basé sur une adaptation de l'algorithme SRSH. Nous avons réussi à proposer deux nouvelles variantes, aussi stables que possible : JHMSH et JHMSH2. Nous avons constaté que ces algorithmes se comportent d'une manière similaire à l'algorithme JHESS. Une caractéristique importante de tous ces algorithmes est qu'ils peuvent rencontrer un breakdown fatal ou un "near breakdown" rendant impossible la suite des calculs, ou débouchant sur une instabilité numérique, privant le résultat final de toute signification. Ce phénomène n'a pas d'équivalent dans le cas Euclidien. Nous avons réussi à élaborer une stratégie très efficace pour "guérir" le breakdown fatal et traîter le near breakdown. Les nouveaux algorithmes intégrant cette stratégie sont désignés par MJHESS, MJHSH, JHM²SH et JHM²SH2. Ces stratégies ont été ensuite intégrées dans la version implicite de l'algorithme SR lui permettant de surmonter les difficultés rencontrées lors du fatal breakdown ou du near breakdown. Rappelons que, sans ces stratégies, l'algorithme SR s'arrête. Finalement, et dans un autre cadre de matrices structurées, nous avons présenté un algorithme robuste via FFT et la matrice de Hankel, basé sur le calcul approché de plus grand diviseur commun (PGCD) de deux polynômes, pour résoudre le problème de la déconvolution d'images. Plus précisément, nous avons conçu un algorithme pour le calcul du PGCD de deux polynômes bivariés. La nouvelle approche est basée sur un algorithme rapide, de complexité quadratique O(n²), pour le calcul du PGCD des polynômes unidimensionnels. La complexité de notre algorithme est O(n²log(n)) où la taille des images floues est n x n. Les résultats expérimentaux avec des images synthétiquement floues illustrent l'efficacité de notre approche. / The classical linear algebra methods, for calculating eigenvalues and eigenvectors of a matrix, or lower-rank approximations of a solution, etc....do not consider the structures of matrices. Such structures are usually destroyed in the numerical process. Alternative structure-preserving methods are the subject of an important interest mattering to the community. This thesis establishes a contribution in this field. The SR decomposition is usually implemented via the symplectic Gram-Schmidt algorithm. As in the classical case, a loss of orthogonality can occur. To remedy this, we have proposed two algorithms RSGSi and RMSGSi, where the reorthogonalization of a current set of vectors against the previously computed set is performed twice. The loss of J-orthogonality has significantly improved. A direct rounding error analysis of symplectic Gram-Schmidt algorithm is very hard to accomplish. We managed to get around this difficulty and give the error bounds on the loss of the J-orthogonality and on the factorization. Another way to implement the SR decomposition is based on symplectic Householder transformations. An optimal choice of free parameters provided an optimal version of the algorithm SROSH. However, the latter may be subject to numerical instability. We have proposed a new modified version SRMSH, which has the advantage of being numerically more stable. By a detailes study, we are led to two new variants numerically more stables : SRMSH and SRMSH2. In order to build a SR algorithm of complexity O(n³), where 2n is the size of the matrix, a reduction to the condensed matrix form (upper J-Hessenberg form) via adequate similarities is crucial. This reduction may be handled via the algorithm JHESS. We have shown that it is possible to perform a reduction of a general matrix, to an upper J-Hessenberg form, based only on the use of symplectic Householder transformations. The new algorithm, which will be called JHSH algorithm, is based on an adaptation of SRSH algorithm. We are led to two news variants algorithms JHMSH and JHMSH2 which are significantly more stable numerically. We found that these algortihms behave quite similarly to JHESS algorithm. The main drawback of all these algorithms (JHESS, JHMSH, JHMSH2) is that they may encounter fatal breakdowns or may suffer from a severe form of near-breakdowns, causing a brutal stop of the computations, the algorithm breaks down, or leading to a serious numerical instability. This phenomenon has no equivalent in the Euclidean case. We sketch out a very efficient strategy for curing fatal breakdowns and treating near breakdowns. Thus, the new algorithms incorporating this modification will be referred to as MJHESS, MJHSH, JHM²SH and JHM²SH2. These strategies were then incorporated into the implicit version of the SR algorithm to overcome the difficulties encountered by the fatal breakdown or near-breakdown. We recall that without these strategies, the SR algorithms breaks. Finally ans in another framework of structured matrices, we presented a robust algorithm via FFT and a Hankel matrix, based on computing approximate greatest common divisors (GCD) of polynomials, for solving the problem pf blind image deconvolution. Specifically, we designe a specialized algorithm for computing the GCD of bivariate polynomials. The new algorithm is based on the fast GCD algorithm for univariate polynomials , of quadratic complexity O(n²) flops. The complexitiy of our algorithm is O(n²log(n)) where the size of blurred images is n x n. The experimental results with synthetically burred images are included to illustrate the effectiveness of our approach