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Global finite-time observers for a class of nonlinear systemsLi, Yunyan January 2013 (has links)
The contributions of this thesis lie in the area of global finite-time observer design for a class of
nonlinear systems with bounded rational and mixed rational powers imposed on the incremental rate
of the nonlinear terms whose solutions exist and are unique for all positive time. In the thesis, two
different kinds of nonlinear global finite-time observers are designed by employing of finite-time
theory and homogeneity properties with different methods. The global finite-time stability of both
proposed observers is derived on the basis of Lyapunov theory.
For a class of nonlinear systems with rational and mixed rational powers imposed on the nonlinearities,
the first global finite-time observers are designed, where the global finite-time stability of the
observation systems is achieved from two parts by combining asymptotic stability and local finitetime
stability. The proposed observers can only be designed for the class of nonlinear systems with
dimensions greater than 3. The observers have a dynamic high gain and two homogenous terms, one
homogeneous of degree greater than 1 and the other of degree less than 1. In order to prove the global
finite-time stability of the proposed results, two homogeneous Lyapunov functions are provided, corresponding
with the two homogeneous items. One is homogeneous of degree greater than 1, which
makes the observation error systems converging into a spherical area around the origin, and the other
is of degree less than 1, which ensures local finite-time stability.
The second global finite-time observers are also proposed based on the high-gain technique, which
does not place any limitation on the dimension of the nonlinear systems. Compared with the first
global finite-time observers, the newly designed observers have only one homogeneous term and a
new gain update law where two new terms are introduced to dominate some terms in the nonlinearities
and ensure global finite-time stability as well. The global finite-time stability is obtained directly
based on a sufficient condition of finite-time stability and only one Lyapunov function is employed in
the proof.
The validity of the two kinds of global finite-time observers that have been designed is illustrated through some simulation results. Both of them can make the observation error systems converge to
the origin in finite-time. The parameters, initial conditions as well as the high gain do have some
impact on the convergence time, where the high gain plays a stronger role. The bigger the high gain
is, the shorter the time it needs to converge. In order to show the performance of the two kinds of
observers more clearly, two examples are provided and some comparisons are made between them.
Through these, it can be seen that under the same parameters and initial conditions, although the
amplitude of the observation error curve is slightly greater, the global finite-time observers with a
new gain update law can make the observation error systems converge much more quickly than the
global finite-time observers with two homogeneous terms. In the simulation results, one can see that,
as a common drawback of high gain observers, they are noise-sensitive. Finding methods to improve
their robustness and adaptiveness will be quite interesting, useful and challenging. / Thesis (PhD)--University of Pretoria, 2013. / gm2014 / Electrical, Electronic and Computer Engineering / unrestricted
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Untersuchung zur prädiktiven Validität von Konzentrationstests: Ein chronometrischer Ansatz zur Überprüfung der Rolle von Itemschwierigkeit, Testlänge, und TestdiversifikationSchumann, Frank 06 June 2016 (has links)
In der hier vorliegenden Arbeit wurde die Validität von Aufmerksamkeits- und Konzentrationstests untersucht. Im Vordergrund stand dabei die Frage nach dem Einfluss verschiedener kritischer Variablen auf die prädiktive Validität in diesen Tests, insbesondere der Itemschwierigkeit und Itemhomogenität, der Testlänge bzw. des Testverlaufs, der Testdiversifikation und der Validität im Kontext einer echten Personalauslese. In insgesamt fünf Studien wurden die genannten Variablen systematisch variiert und auf ihre prädiktive Validität zur (retrograden und konkurrenten) Vorhersage von schulischen und akademischen Leistungen (Realschule, Abitur, Vordiplom/Bachelor) hin analysiert. Aufgrund der studentischen (d. h. relativ leistungshomogenen) Stichprobe bestand die Erwartung, dass die Korrelationen etwas unterschätzt werden. Da die Validität in dieser Arbeit jedoch „vergleichend“ für bestimmte Tests bzw. experimentelle Bedingungen bestimmt wurde, sollte dies keine Rolle spielen. In Studie 1 (N = 106) wurde zunächst untersucht, wie schwierig die Items in einem Rechenkonzentrationstest sein sollten, um gute Vorhersagen zu gewährleisten. Dazu wurden leichte und schwierigere Items vergleichend auf ihre Korrelation zum Kriterium hin untersucht. Im Ergebnis waren sowohl leichte als auch schwierigere Testvarianten ungefähr gleich prädiktiv. In Studie 2 (N = 103) wurde die Rolle der Testlänge untersucht, wobei die prädiktive Validität von Kurzversion und Langversion in einem Rechenkonzentrationstest vergleichend untersucht wurde. Im Ergebnis zeigte sich, dass die Kurzversion valider war als die Langversion und dass die Validität in der Langversion im Verlauf abnimmt. In Studie 3 (N = 388) stand der Aspekt der Testdiversifikation im Vordergrund, wobei untersucht wurde, ob Intelligenz besser mit einem einzelnen Matrizentest (Wiener Matrizen-Test, WMT) oder mit einer Testbatterie (Intelligenz-Struktur-Test, I-S-T 2000 R) erfasst werden sollte, um gute prädiktive Validität zu gewährleisten. Die Ergebnisse sprechen klar für den Matrizentest, welcher ungefähr gleich valide war wie die Testbatterie, aber dafür testökonomischer ist. In den Studien 4 (N = 105) und 5 (N =97) wurde die prädiktive Validität zur Vorhersage von Schulleistungen im Kontext einer realen Personalauswahlsituation untersucht. Während die großen Testbatterien, Wilde-Intelligenz-Test 2 (WIT-2) und Intelligenz-Struktur-Test 2000R (I-S-T 2000 R), nur mäßig gut vorhersagen konnten, war der Komplexe Konzentrationstest (KKT), insbesondere der KKT-Rechentest ein hervorragender Prädiktor für schulische und akademische Leistungen. Auf Basis dieser Befunde wurden schließlich Empfehlungen und Anwendungshilfen für den strategischen Einsatz von Testinstrumenten in der diagnostischen Berufspraxis ausgesprochen.:1 Einführung und Ziele
2 Diagnostik von Konzentrationsfähigkeit
2.1 Historische Einordnung
2.2 Kognitive Modellierung
2.3 Psychometrische Modellierung
3 Prädiktive Validität von Konzentrationstests
3.1 Reliabilität, Konstruktvalidität, Kriterienvalidität
3.2 Konstruktions- und Validierungsstrategien
3.3 Ableitung der Fragestellung
4 Beschreibung der Fragebögen und Tests
5 Empirischer Teil
5.1 Studie 1 - Itemschwierigkeit
5.1.1 Methode
5.1.2 Ergebnisse
5.1.3 Diskussion
5.2 Studie 2 - Testverlängerung und Testverlauf
5.2.1 Methode
5.2.2 Ergebnisse
5.2.3 Diskussion
5.3 Studie 3 - Testdiversifikation
5.3.1 Methode
5.3.2 Ergebnisse
5.3.3 Diskussion
5.4 Studie 4 - Validität in realer Auswahlsituation (I-S-T 2000 R)
5.4.1 Methode
5.4.2 Ergebnisse
5.4.3 Diskussion
5.5 Studie 5 - Validität in realer Auswahlsituation (WIT-2)
5.5.1 Methode
5.5.2 Ergebnisse
5.5.3 Diskussion
6 Diskussion 128
6.1 Sind schwierige Tests besser als leichte Tests?
6.2 Sind lange Tests besser als kurze Tests?
6.3 Sind Testbatterien besser als Einzeltests?
6.4 Sind Tests auch unter „realen“ Bedingungen valide?
6.5 Validität unter realen Bedingungen - Generalisierung
7 Theoretische Implikationen
8 Praktische Konsequenzen
9 Literaturverzeichnis
Anhang
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Ägartyper och deras påverkan på mångfald inom bolagsstyrelser : En kvantitativ studie om mångfalden i svenska styrelser / Ownership types and its impact on diversity in board of directors : A quantitative study of the diversity of Swedish boardsOwada, Khalil, Nord Andersson, Patrik January 2022 (has links)
Bakgrund; Mångfald har under en lång tid varit ett högaktuellt begrepp inom näringslivet. Senaste åren har mångfalden i näringslivet fått mer uppmärksamhet, inte minst i bolagsstyrelser. En växande global marknad har lett till att mångfalden uppmärksammas alltmer. Förespråkarna för mångfald menar att det bidrar till bättre bolagsprestationer medan kritikerna menar att mångfald kan leda till försämrad kommunikation och försämrad konkurrensförmåga. Idag är Sverige ett heterogent land, kan heterogeniteten återfinnas i svenska styrelser och kan olika ägartyper förklara mångfalden i styrelsen. Syfte; Uppsatsens syfte är att förklara om och i så fall hur olika ägartyper kan påverkamångfalden i bolagsstyrelser på den svenska börsmarknaden. Metod; Uppsatsen har en deduktiv forskningsansats, där en modell är grunden som förklarar hur mångfalden utgår ifrån agentteorin, resursberoendeteorin, upper echelon teorin, legitimitetsteorin och gruppkonfliktteorin. Kvantitativa forskningsmetoden bygger på svenskstyrelse-, ägar- och finansiell data från 2021. Slutsatser; Uppsatsen kan konstatera att ägartyper inte kan förklara mångfalden i styrelsen. Uppsatsen ser istället homosocial reproduktion och upper echelon teorin som en möjlig förklaring till att styrelser ser ut som de gör. Styrelser i Sverige är homogena och det krävs stora förändringar för att de skall spegla svenska samhället på bättre sätt. / Bakground; Diversity has for a long time been a topic of discussion. In recent years, diversity in the business community has received more attention, not least in company boards. A growing global market has led to increasing attention to diversity. Proponents of diversity believe that it contributes to better corporate performance, while critics believe that diversity can lead to impaired communication and impaired competitiveness. Today, Sweden is a heterogeneous country, the question is if heterogeneity can be found in Swedish boards and if different types of ownership can explain the diversity of the board. Purpose; The purpose of the thesis is to explain if and how different types of owners can explain the diversity of board of directors in the Swedish stock market. Method; The thesis has a deductive research approach, where a theoretical model is the basis that explains how diversity is based on agent theory, resource dependency theory, upper echelon theory, legitimacy theory and group conflict theory. The quantitative research method is based on Swedish board-, ownership- and financial data from 2021. Conclusion; The thesis can state that ownership types can not explain the diversity of the board. The thesis instead sees homosocial reproduction and the upper echelon theory as a possible recruitment to make boards look the way they do. Boards in Sweden are homogeneous and major changes are required for them to reflect Swedish society in a better way.
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Genus i svenska börsbolagsstyrelser : En studie om sambandet mellan andelen kvinnor i styrelser och den finansiella prestationen i bolagen / Gender in swedish listed company boards : A study on the relationship between the percentage of women on corporate boards and the financial performance of the companyNawroz Jalal, Kani, Dogan, Berivan January 2014 (has links)
Problem: Kvinnor har länge varit underrepresenterade i styrelsesammansättningar runt om i världen. Sverige är ett land som främjar likvärdighet och anses därför vara ett av världens mest jämställda länder. Andelen kvinnor i svenska styrelser har ökat under de senaste årtiondena, men trots detta är de svenska bolagsstyrelserna inte jämställda. Ibland används argumenten att fler kvinnor i styrelsen ökar lönsamheten och effektiviteten i bolaget i syfte att öka kvinnoandelen. Till följd av detta har det internationellt genomförts många studier för att undersöka om bolag med heterogena styrelser har bättre lönsamhet än bolag med homogena styrelser. Forskning har visat att heterogena styrelser samvarierar positivt med bolagens lönsamhet. Men det finns även forskning som visat negativa resultat eller ingen samvariation alls mellan heterogena styrelser och bolagens lönsamhet. Syfte: Studiens huvudsyfte är att analysera hur andelen kvinnor i svenska styrelser samvarierar med bolagens lönsamhet. Arbetet omfattar åren 2011, 2012 och 2013 för att visa hur utvecklingen har sett ut över tid. Studien syftar även till att jämföra tidigare internationella studier med svenska förhållanden, där den med hjälp av kulturdimensionsteori som försöker förklara de nationella kulturskillnader som föreligger. Metod: En kvantitativ metod har tillämpats för att studera bolagens lönsamhet med hjälp av finansiella nyckeltal i årsredovisningar. Bolagens lönsamhet har mätts i räntabilitet på totalt kapital och räntabilitet på eget kapital. Vidare har heterogena styrelser och homogena styrelser jämförts genom t-tester och korrelationsanalyser, för att undersöka sambandet mellan variablerna lönsamhet och andelen kvinnor i svenska bolagsstyrelser. Analys och slutsats: Studiens resultat visade att det inte finns något samband mellan heterogena styrelser och lönsamhet i svenska börsbolag. Studien visade även att Sverige har en högre andel kvinnliga styrelsemedlemmar än andra länder i världen. Detta kan förklaras med hjälp av kulturdimensionsteorierna maktdistans samt maskulinitet kontra femininitet som visar nationella kulturskillnader i näringslivet. / Problem: Women have for a long time been underrepresented on corporate boards all around the world. Sweden is a country that promotes equality and is therefore considered as one of the most equal countries. The percentages of women in Swedish boards have increased markedly in recent decades, but they are still far from equal. To increase the percentage of women on boards it is sometimes advocated that more women on boards increases the company’s profitability. As a result of this many international studies have investigated if companies with heterogeneous are more profitable than companies with homogeneous board. Research has shown that heterogeneous boards are positively correlated with firm profitability. Research has also shown negative results or no correlation between heterogeneous boards and firm profitability. Purpose: This study's main purpose is to examine how the percentage of women in the Swedish boards correlates with the companies' profitability. The study covers the years 2011, 2012 and 2013 to show the development of board members over the years. Furthermore this study aims to compare previous international studies with Swedish conditions by comparing national cultural differences. Method: A quantitative method has been applied to study the company's profitability with the help of financial ratios in annual reports. The company’s profitability has been measured in return on assets and return on equity. Furthermore heterogeneous boards and homogeneous boards have been compared with statistic t-tests and correlation analyzes to examine the relationship between the variables of profitability and the percentage of women in Swedish company boards. Analysis and conclusion: The results of the study showed that there is no correlation between heterogeneous boards and firm profitability in Swedish listed companies. The study also showed that Sweden has a higher percentage of female board members than other countries in the world. This can be explained by cultural dimension theories, power distance and masculinity versus femininity showing national cultural differences.
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Using Model Theory to Find Decidable and Tractable Description Logics with Concrete DomainsBaader, Franz, Rydval, Jakub 22 February 2024 (has links)
Concrete domains have been introduced in the area of Description Logic to enable reference to concrete objects (such as numbers) and predefined predicates on these objects (such as numerical comparisons) when defining concepts. Unfortunately, in the presence of general concept inclusions (GCIs), which are supported by all modern DL systems, adding concrete domains may easily lead to undecidability. To regain decidability of the DL ALC in the presence of GCIs, quite strong restrictions, in sum called ω-admissibility, were imposed on the concrete domain. On the one hand, we generalize the notion of ω-admissibility from concrete domains with only binary predicates to concrete domains with predicates of arbitrary arity. On the other hand, we relate ω-admissibility to well-known notions from model theory. In particular, we show that finitely bounded homogeneous structures yield ω-admissible concrete domains. This allows us to show ω-admissibility of concrete domains using existing results from model theory. When integrating concrete domains into lightweight DLs of the E L family, achieving decidability is not enough. One wants reasoning in the resulting DL to be tractable. This can be achieved by using so-called p-admissible concrete domains and restricting the interaction between the DL and the concrete domain. We investigate padmissibility from an algebraic point of view. Again, this yields strong algebraic tools for demonstrating p-admissibility. In particular, we obtain an expressive numerical p-admissible concrete domain based on the rational numbers. Althoughω-admissibility and p-admissibility are orthogonal conditions that are almost exclusive, our algebraic characterizations of these two properties allow us to locate an infinite class of p-admissible concrete domains whose integration into ALC yields decidable DLs.
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Using model theory to find w-admissible concrete domainsBaader, Franz, Rydval, Jakub 20 June 2022 (has links)
Concrete domains have been introduced in the area of Description Logic to enable reference to concrete objects (such as numbers) and predefined predicates on these objects (such as numerical comparisons) when defining concepts. Unfortunately, in the presence of general concept inclusions (GCIs), which are supported by all modern DL systems, adding concrete domains may easily lead to undecidability. One contribution of this paper is to strengthen the existing undecidability results further by showing that concrete domains even weaker than the ones considered in the previous proofs may cause undecidability. To regain decidability in the presence of GCIs, quite strong restrictions, in sum called w-admissiblity, need to be imposed on the concrete domain. On the one hand, we generalize the notion of w-admissiblity from concrete domains with only binary predicates to concrete domains with predicates of arbitrary arity. On the other hand, we relate w-admissiblity to well-known notions from model theory. In particular, we show that finitely bounded, homogeneous structures yield w-admissible concrete domains. This allows us to show w-admissibility of concrete domains using existing results from model theory.
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Operations research models for the management of supply chains of perishable and heterogeneous products in uncertain contexts. Application to the agri-food and ceramic sectorsEsteso Álvarez, Ana 12 March 2022 (has links)
Tesis por compendio / [ES] Algunos productos se caracterizan por su falta de homogeneidad, lo que significa que productos con diferentes características pueden ser obtenidos de un mismo proceso de producción debido a factores incontrolables como la naturaleza de las materias primas o las condiciones ambientales durante la producción. Hay cuatro aspectos que caracterizan la falta de homogeneidad en el producto: los subtipos homogéneos que se obtienen de un mismo lote de producción, la cantidad de productos que componen cada subtipo, el valor de cada uno de los subtipos, y el estado de los productos.
La falta de homogeneidad en el producto dificulta la gestión de los procesos de las empresas y cadenas de suministro en el momento en el que los clientes requieren homogeneidad entre las unidades de producto que adquieren. Un ejemplo de esto se produce en el sector de la cerámica, en el que los clientes requieren que todas las unidades que van a ser ensambladas juntas tengan el mismo color, espesor y calidad por razones estéticas y de seguridad. Otro ejemplo es el extraído del sector agroalimentario, en el que el mercado final requiere productos que cumplan con un tamaño mínimo, un color particular, o sabor en el caso de las frutas. Además, el sector agroalimentario tiene la complejidad añadida producida por el deterioro de los productos a lo largo del tiempo, y la necesidad de los mercados de ofrecer a los clientes productos con una mínima duración tras su venta.
En esta Tesis, se define como productos heterogéneos a aquellos productos que se pueden clasificar en subtipos homogéneos con una cantidad variable, mientras que los productos perecederos son aquellos que, además de ser heterogéneos, tienen falta de homogeneidad en su estado. De acuerdo con estos conceptos, el sector cerámico comercializa productos heterogéneos mientras que el sector agroalimentario comercializa productos perecederos.
Esta Tesis propone marcos conceptuales y modelos de Investigación Operativa que soporten la gestión de cadenas de suministro con productos heterogéneos y perecederos en la toma de decisiones centralizada y distribuidas relacionadas con los niveles de decisión estratégica, táctica y operativa. El objetivo es mejorar la competitividad, sostenibilidad y flexibilidad de la cadena de suministro para adaptarse a los requerimientos del mercado bajo condiciones de incertidumbre. Para esto, se han propuesto modelos de Investigación Operativa deterministas e inciertos, cuyos resultados se comparan concluyendo que los resultados obtenidos con los modelos inciertos se adaptan mejor al comportamiento real de las cadenas de suministros.Los modelos de Investigación Operativa propuestos han contribuido a tres áreas de investigación: problemas operativos en el sector cerámico, problemas estratégicos en el sector agroalimentario y problemas de planificación en el sector agroalimentario.
Las principales novedades en los problemas operativos en el sector cerámico son el modelado de las características de las baldosas cerámicas, la consideración de los requerimientos de homogeneidad entre unidades de diferentes líneas de pedido, y la posibilidad de realizar entregas parciales y entregas con retraso.
Esta Tesis contribuye a los problemas estratégicos en el sector agroalimentario al diseñar una cadena de suministro completa de productos agroalimentarios frescos considerando el aspecto perecedero de los productos e integrando decisiones tácticas, y determinando el impacto real que tiene considerar el aspecto perecedero de los productos durante el diseño de la cadena de suministro ... / [CA] Alguns productes es caracteritzen per la seua falta d'homogeneïtat, el que significa que productes amb diferents característiques poden ser obtinguts d'un mateix procés de producció degut a factors incontrolables com la naturalesa de les matèries primeres o les condicions ambientals durant la producció. Hi ha quatre aspectes que caracteritzen la falta d'homogeneïtat en el producte: els subtipus homogenis que s'obtenen d'un mateix lot de producció, la quantitat de productes que componen cada subtipus, el valor de cada un dels subtipus, i l'estat dels productes.
La falta d'homogeneïtat en el producte dificulta la gestió dels processos de les empreses i cadenes de subministrament en el moment en què els clients requerixen homogeneïtat entre les unitats de producte que adquirixen. Un exemple d'açò es produïx en el sector de la ceràmica, en el que els clients requerixen que totes les unitats que seran acoblades juntes tinguen el mateix color, grossària i qualitat per raons estètiques i de seguretat. Un altre exemple és l'extret del sector agroalimentari, en el que el mercat final requerix productes que complisquen amb una grandària mínima, un color particular, o sabor en el cas de les fruites. A més, el sector agroalimentari té la complexitat afegida produïda pel deteriorament dels productes al llarg del temps, i la necessitat dels mercats d'oferir als clients productes amb una mínima duració després de la seua venda.
En aquesta Tesi, es definix com a productes heterogenis a aquells productes que es poden classificar en subtipus homogenis amb una quantitat variable, mentres que els productes peribles són aquells que, a més de ser heterogenis, tenen falta d'homogeneïtat en el seu estat. D'acord amb aquests conceptes, el sector ceràmic comercialitza productes heterogenis mentres que el sector agroalimentari comercialitza productes peribles.
Aquesta Tesi proposa marcs conceptuals i models d'Investigació Operativa que suporten la gestió de cadenes de subministrament amb productes heterogenis i peribles en la presa de decisions centralitzada i distribuïdes relacionades amb els nivells de decisió estratègica, tàctica i operativa. L'objectiu és millorar la competitivitat, sostenibilitat i flexibilitat de la cadena de subministrament per adaptar-se als requeriments del mercat sota condicions d'incertesa. Per a açò, s'han proposat models d'Investigació Operativa deterministes i incerts, els resultats es comparen concloent que els resultats obtinguts amb els models incerts s'adapten millor al comportament real de les cadenes de subministraments.
Els models d'Investigació Operativa proposats han contribuït a tres àrees d'investigació: problemes operatius en el sector ceràmic, problemes estratègics en el sector agroalimentari i problemes de planificació en el sector agroalimentari.
Les principals novetats en els problemes operatius en el sector ceràmic són el modelatge de les característiques de les rajoles ceràmiques, la consideració dels requeriments d'homogeneïtat entre unitats de diferents línies de comanda, i la possibilitat de realitzar lliuraments parcials i lliuraments amb retard.
Aquesta Tesi contribueix als problemes estratègics en el sector agroalimentari al dissenyar una cadena de subministrament completa de productes agroalimentaris frescos considerant l'aspecte perible dels productes, integrant decisions tàctiques, i determinant l'impacte real que té considerar l'aspecte perible dels productes durant el disseny de la cadena de subministrament ... / [EN] Some products are characterised by their lack of homogeneity, what means that products with different characteristics can be obtained from the same production process due to uncontrollable factors such as the nature of raw materials or the environmental conditions during production. There are four aspects that characterize the lack of homogeneity in the product: the homogeneous subtypes to be obtained from a production lot, the quantity of products that belong to each subtype, the value related to each of the subtypes and the state of the products.
The lack of homogeneity in the product hinders the management of the supply chain or company's processes at the time customers require the homogeneity among the acquired units of product. An example of this is produced in the ceramic tile sector, in which customers need all acquired ceramic tiles that are going to be jointly assembled to have the same colour, thickness and quality for aesthetic and safety reasons. Another example is the extracted from the agri-food sector, in which final markets require products that meet some characteristics such as a minimum size, a particular colour or flavour in the case of fruits. In addition, the agri-food sector has the added complexity produced by the deterioration of products over time, and the need of markets to offer to end consumers products with a minimum durability after sale.
In this Thesis, heterogeneous products are defined as products for which different subtypes can be obtained in a variable quantity while perishable products are those that, apart from being heterogeneous, have a lack of homogeneity in their state. According to these concepts, ceramic sectors would commercialize heterogeneous products while the agri-food sector would do so with perishable products.
This Thesis proposes conceptual frameworks and Operations Research models to support the management of supply chains with heterogeneous and perishable products in centralized and distributed decision-making processes related to strategic, tactical and operative decisional levels. The objective is to improve the supply chain competitiveness, sustainability and flexibility to adapt to market requirements under uncertain conditions. For this, both deterministic and uncertain Operations Research models have been proposed, whose results are compared concluding that results obtained with uncertain models better fit with the behaviour of real supply chains.
The proposed Operations Research models have contributed to three research areas: operational problems in the ceramic sector, strategic problems in the agri-food sector and planning problems in the agri-food sector.
Main novelties in the ceramic operational problems are the modelling of the characteristics of ceramic tile products, the consideration of homogeneity requirements between units from different order lines, and the possibility of making partial deliveries and delayed deliveries.
This Thesis contributes to strategic problems in agri-food products by designing an entire fresh agri-food supply chain considering the perishability of products and integrating tactical decisions, and by determining the real impact that considering the products' perishability has on the supply chain design process ... / This Thesis has been developed in the Research Centre of Management and Production
Engineering (CIGIP, for its acronym in Spanish “Centro de Investigación en Gestión e
Ingeniería de Producción”) of the Universitat Politècnica de València with the support of
the predoctoral grant Programme of Formation of University Professors (FPU, for its
acronym in Spanish “Formación de Profesorado Universitario”) from the Spanish
Ministry of Science, Innovation and Universities (Ref. FPU15/03595). The supervisors
of this Thesis are Dr. Angel Ortiz, and Dra. María del Mar Alemany Diaz that are
Professors in the Research Centre of Management and Production Engineering (CIGIP)
of the Universitat Politècnica de València. The FPU grant has been endorsed by the
supervisor Dr. Ángel Ortiz.
This Thesis has also been supported by the project ‘RUC-APS: Enhancing and
implementing Knowledge based ICT solutions within high Risk and Uncertain
Conditions for Agriculture Production Systems’ (Ref. 691249) funded by the EU under
its funding scheme H2020-MSCA-RISE-2015, the project ‘Methods and models for operations planning and order management in supply chains characterised by uncertainty
in production due to the lack of product uniformity’ (PLANGES-FHP) (Ref. DPI2011-
23597) funded by the Spanish Ministry of Economy and Competitiveness. The projects
RUC-APS and PLANGES-FHP have been led by the one of the supervisors of this Thesis
Dr. María del Mar Eva Alemany.
In order to obtain the international mention for this Thesis, three months of research
stages have been made in the research agency Agenzia Lucana di Sviluppo e di
Innovazione in Agricoltora, located in Metaponto (Italy) / Esteso Álvarez, A. (2020). Operations research models for the management of supply chains of perishable and heterogeneous products in uncertain contexts. Application to the agri-food and ceramic sectors [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/141099 / TESIS / Compendio
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Le pacte fédératif européen / The european federal compactDechâtre, Laurent 12 December 2012 (has links)
Dans le cadre du renouvellement doctrinal sur les unions fédérales, nous proposons une définition du pacte fédératif qui se fonde sur l'étude des systèmes fédéraux allemand, américain, et suisse dans la perspective d'une qualification juridique des traités européens. Le pacte fédératif est un acte conclu volontairement entre des Etats fondant une institution, la Fédération, qui constitue une union politique. La stabilité de cette Fédération impose des mécanismes assurant sa cohérence et le respect du droit fédéral, ainsi que le développement d'un sentiment d'appartenance fédéral. Mais les autorités fédérales doivent à l'inverse respecter l'intégrité des Etats membres. Si l'un de ces éléments n'est pas respecté la Fédération risque d'imploser ou de se transformer en Etat fédéral. L'Union européenne répond globalement à ces critères de définition, ce qui permet sa qualification de Fédération. L'étude de son fonctionnement permet également de mettre en évidence un respect général de l'équilibre entre les niveaux fédéral et fédéré nécessaire à sa pérennisation en tant que Fédération. Au plan matériel, l'équilibre entre impératif de bon fonctionnement de la Fédération et le respect de l'intégrité des Etats membres ne fait pas l'objet de tensions avec les Etats membres, que ce soit au niveau de la répartition comme de l'exercice des compétences. Au plan institutionnel, le processus décisionnel a dû s'adapter au renforcement de l'intégration européenne. On constate notamment un renforcement de la légitimité démocratique, condition préalable au développement d'un sentiment d'appartenance européen, même si des améliorations restent nécessaires. Le reproche de déficit démocratique lié à l'absence d'alternative partisane paraît plus difficile à résoudre car le facteur partisan n'est pas aisé à concilier avec la logique de fonctionnement des institutions européennes qui impose une forme de compromis. / As part of the renewal of the doctrin regarding federal unions, I suggest a definition of the federal compact which is based on the study of the German, the American and the Swiss federal systems in order to find a legal classification for the European treaties. The federal compact is an act voluntarily concluded between states founding an "institution", the Federation, which is a political union. The stability of this Federation implies mechanisms which safeguard consistency and compliance with federal law ; besides it requires the development of a federal sense of belonging. But conversely, federal authorities have to respect the member states’ integrity. If one of those criteria is not met, the Federation may collapse or turn into a federal state. The European Union meets these criteria completely, which allows its characterization as Federation. The study of its functioning enables then to highlight a global compliance of the balance between federal and state level, which is necessary for the Federation’s stability. On the material level, the balance between the obligation of a good functioning Federation on the one hand and the respect of the member states on the other doesn't turn into a conflict with the member states, neither in regard of the allocation of power nor in regard of the exercise of power. On the institutional level, decisional process had to be adapted to a deeper European integration. There is in particular a strengthened democratic legitimacy, which is required for a European sense of belonging to develop, even though improvements are still necessary. It seems more difficult to solve the problem of the criticism related to the lack of democracy based on the absence of political challenge because political challenge is not easy to achieve given the compromise-based way the European institution function.
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Comparação entre métodos de imputação de dados em diferentes intensidades amostrais na série homogênea de precipitação pluvial da ESALQ / Comparison between data imputation methods at different sample intensities in the ESALQ homogeneous rainfall seriesGasparetto, Suelen Cristina 07 June 2019 (has links)
Problemas frequentes nas análises estatísticas de informações meteorológicas são a ocorrência de dados faltantes e ausência de conhecimento acerca da homogeneidade das informações contidas no banco de dados. O objetivo deste trabalho foi testar e classificar a homogeneidade da série de precipitação pluvial da estação climatológica convencional da ESALQ, no período de 1917 a 1997, e comparar três métodos de imputação de dados, em diferentes intensidades amostrais (5%, 10% e 15%) de informações faltantes, geradas de forma aleatória. Foram utilizados três testes de homogeneidade da série: Pettitt, Buishand e normal padrão. Para o \"preenchimento\" das informações faltantes, foram comparados três métodos de imputação múltipla: PMM (Predictive Mean Matching), random forest e regressão linear via método bootstrap, em cada intensidade amostral de informações faltantes. Os métodos foram utilizados por meio do pacote MICE (Multivariate Imputation by Chained Equations) do R. A comparação entre cada procedimento de imputação foi feita por meio da raiz do erro quadrático médio, índice de exatidão de Willmott e o índice de desempenho. A série de chuva foi entendida como de classe 1, ou seja, \"útil\" - Nenhum sinal claro de falta de homogeneidade foi aparente e, o método que resultou em menores valores da raiz quadrada dos erros e maiores índices foi o PMM, em especial na intensidade de 10% de informações faltantes. O índice de desempenho para os três métodos de imputação de dados em todas as intensidades de observações faltantes foi considerado \"Péssimo\" / Frequent problems in the statistical analyzes of meteorological information are the occurrence of missing data and missing of knowledge about the homogeneity of the information contained in the data base. The objective of this work was to test and classify the homogeneity of the rainfall series of the conventional climatological station of the ESALQ from 1917 to 1997 and to compare three methods of data imputation in different sample intensities (5%, 10% and 15%), of missing data, generated in a random way. Three homogeneity tests were used: Pettitt, Buishand and standard normal. For the \"filling\" of missing information, three methods of multiple imputation were compared: PMM (Predictive Mean Matching), random forest and linear regression via bootstrap method, in each sampling intensity of missing information. The methods were used by means of the MICE (Multivariate Imputation by Chained Equations) package of R. The comparison of each imputation procedure was done by root mean square error, Willmott\'s accuracy index and performance index. The rainfall series was understood to be class 1 \"useful\" - No clear sign of lack of homogeneity was apparent and the method that resulted in smaller values of the square root of the errors and higher indexes was the PMM, in particular the intensity of 10% of missing information. The performance index for the three methods of imputation the data at all missing observation intensities was considered \"Terrible\"
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Mångfald i företagsledningen : En studie utifrån vd:s, styrelseordförandens och styrelsens generationstillhörighet i svenska börsnoterade företag / Diversity in corporate management : A study based on the CEO's, chairman of the board’s and the board's generation affiliation in Swedish listed companiesSternegård, Alma, Karlsson, Felicia January 2019 (has links)
Bakgrund och problem: Bakgrunden till denna studie ligger i bristen av mångfald i svenska företagsledningar. För att skapa en större förståelse för rekryteringen av individer till företagsledningen, kan det således vara av betydelse att studera de individer som tillsätter ledningen, det vill säga vd, styrelseordförande och styrelsen. Dessa ledande positioner förväntas påverkas av betydande händelser och erfarenheter i deras formativa år, och således bilda unika värderingar vilket kan påverka deras val av individer till företagsledningen. Det är därmed intressant att förstå om och i så fall hur ledande positioners generationstillhörighet kan förklara mångfalden i företagsledningen. Syfte: Studiens syfte är att förklara om och hur ledande positioner såsom vd:s, styrelseordförandens samt styrelseledamöters generationstillhörighet kan förklara mångfalden i företagsledningen. Metod: Undersökningen utgår från befintlig teori och har en deduktiv ansats, med en teoretisk grund utifrån gruppkonfliktsteorin, sociala identitetsteorin, homosocial reproduktion, legitimitetsteorin och institutionella teorin. Hypoteser formuleras utifrån vd:s, styrelseordförandens och styrelsens generationstillhörighet för att studera om olika generationer har skilda värderingar som i sin tur kan förklara mångfalden i företagsledningen. Uppsatsen är kvantitativ och studerar samtliga svenska börsnoterade företag på large-, mid- och small cap för åren 2007 respektive 2017. Resultat och slutsats: Det kan konstateras att ledande positioners generationstillhörighet inte kan förklara mångfalden i företagsledningen. Denna studie ser istället tendenser av homosocial reproduktion vid rekrytering av individer till företagsledningen. / Background and problem: The background to this study lies in the lack of diversity in Swedish top management teams. In order to create a greater understanding of the recruitment of individuals to the top management team, it can thus be of importance to study the individuals who appoint the management, that is, the CEO, the chairman of the board and the board. These leading positions are expected to be influenced by significant events and experiences in their formative years, thus forming unique values which can affect their choice of individuals to the top management team. It is therefore interesting to understand whether and, if so, how leading positions' generation affiliation can explain the diversity in top management teams. Purpose: Our purpose is to explain whether and how leading positions such as the CEO's, the Chairman’s of the Board and the Board of Directors generation affiliation can explain the diversity in top management teams. Method: The study is based on existing theory and has a deductive approach, with a theoretical basis based on group conflict theory, social identity theory, homosocial reproduction, legitimacy theory and institutional theory. Hypotheses are formulated on the basis of the CEO's, the Chairman's and the Board's generation affiliation in order to study whether different generations have different values which in turn can explain the diversity of the top management team. The thesis is quantitative and studies all Swedish listed companies on large, mid and small cap for the years 2007 and 2017. Results and conclusion: It can be concluded that the leading positions generation affiliation can not explain the diversity in top management teams. Instead, this study sees tendencies of homosocial reproduction when recruiting individuals to top management teams.
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