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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.
261

Tratado do espaço de 1967 : legado e desafios para o direito espacial.

Andrade, Jonathan Percivalle de 23 June 2016 (has links)
Submitted by Rosina Valeria Lanzellotti Mattiussi Teixeira (rosina.teixeira@unisantos.br) on 2016-08-23T18:13:08Z No. of bitstreams: 1 Jonathan Percivalle de Andrade.pdf: 683531 bytes, checksum: 48f515eaf3b0e1b6be912cb03ec303bd (MD5) / Made available in DSpace on 2016-08-23T18:13:08Z (GMT). No. of bitstreams: 1 Jonathan Percivalle de Andrade.pdf: 683531 bytes, checksum: 48f515eaf3b0e1b6be912cb03ec303bd (MD5) Previous issue date: 2016-06-23 / This work aims, in the light of International Law, to study the Outer Space Treaty, as structuring instrument of the international regime for outer space; highlighting its legacy and the challenges that are currently faced by Space Law, analyzed from the perspective of the Convention. In regard to the methodology, it was elected the deductive method, using extensive literature search. In the first chapter, the historical development of Space Law is studied, which is intertwined with the history of the "Space Age" itself, wich began with the launch of Sputnik I in 1957; in the same chapter the five treaties that combined form the corpus iuris of International Law are also studied. In the second chapter, the Outer Space Treaty is approached by a precise analysis of its devices under the perspective of Internacional Law. The common good clause, the principle of non-appropriation, the demilitarization of space, the astronauts, States¿ responsibility for damage caused by space activities and the prospects of cooperation in and to Space are analyzed. Lastly, the third chapter brings the challenges of Space Law in the twenty-first century analyzed in the light of Outer Space Treaty. The study is based on the delimitation of bordes¿s issue between air and outer space, space debris and the exploitation of natural resources and the participation of private companies. It is concluded that although relevant to Space Law, meeting the demands placed at the time, the 1967¿s Outer Space Treaty is no longer able to meet these and other challenges that are currently imposed. / O presente trabalho tem por objetivo, à luz do Direito Internacional, estudar o Tratado do Espaço de 1967, enquanto norma estruturadora do regime internacional para o espaço exterior, destacando-se seu legado e os desafios com os quais se depara o Direito Espacial atualmente, analisados sob a perspectiva da referida convenção. No tocante à metodologia, elege-se o método dedutivo, utilizando-se de extensiva pesquisa bibliográfica. No primeiro capítulo do trabalho, é realizado o estudo da evolução história do Direito Espacial, que se confunde com a história da própria ¿Era Espacial¿, inaugurada com o lançamento do Sputnik I em 1957; no mesmo capítulo são estudados, também, os cinco tratados que formam o corpus iuris do Direito Internacional. No segundo capítulo, o Tratado do Espaço de 1967 é abordado por intermédio de precisa análise de seus dispositivos sob à ótica do Direito Internacional. São analisados a cláusula do bem comum, o princípio da não-apropriação, a desmilitarização do espaço, os astronautas, a responsabilidade dos Estados por danos causados no espaço exterior e as perspectivas de cooperação no e para o espaço. Por derradeiro, o terceiro capítulo traz os desafios do Direito Espacial no século XXI analisados à luz do Tratado do Espaço de 1967. O estudo paira sobre a questão da delimitação da fronteira entre espaço aéreo e exterior, lixo espacial e a exploração de recursos naturais e a participação de empresas privadas. Conclui-se que ainda que relevante para o Direito Espacial, atendendo às demandas postas à época, o Tratado do Espaço de 1967 não mais consegue dar resposta a estes e outros desafios que lhe são impostos atualmente.
262

The Effects of Sediment Properties on Barrier Island Morphology and Processes: A Numerical Modeling Experiment

Kime, Brittany 20 December 2018 (has links)
Barrier island restoration and nourishment is necessary for sustaining coastal systems worldwide. In the Mississippi River Delta Plain, the lack of sediment supply, relative sea level rise, and reworking of abandoned delta lobes promote rapid disintegration of barriers, which can contribute to mainland storm impacts. Barrier island restorations that utilize higher quality sediments (Outer Continental Shelf- OCS) are expected to exhibit higher resiliency, withstanding coastal erosion, event-induced erosion, and ongoing transgression when compared to barriers nourished using lower quality nearshore (NS) sands. Additionally, use of OCS sediments increases sediment supply by adding material to the system supporting increased barrier longevity by maintaining a subaerial footprint longer compared to NS sediments. We used the Delft3D modeling suite to study barrier geomorphic trajectories nourished using OCS/NS sands, compared with control simulations with no nourishment. Resulting morphologies from 18 simulations with forcing that included annualized forcing, storms, and SLR are evaluated and compared.
263

Designing an overlay hybrid cognitive radio including channel estimation issues

Abdou, Ahmed 04 December 2014 (has links)
La radio intelligente (RI) a été proposée pour améliorer l’utilisation du spectre radiofréquence. Pour cela, il s’agit de donner un accès opportuniste aux utilisateurs non licenciés (nommés utilisateurs secondaires) au spectre alloué à l’utilisateur licencié (nommé utilisateur primaire). Dans cette thèse, notre but est de proposer un scénario spécifique à la RI et de présenter des solutions à certains problèmes connexes. Pour cela, nous considérons une RI émettant ses informations en “sur-couche” des utilisateurs primaires (technique overlay). Le système étudié est constitué d’une macro-cellule primaire et de petites cellules cognitives secondaires équipées de stations de base coopérant ensemble. Nous suggérons l’étude d’un schéma de communication hybride où une modulation “FilterBanc Multi Carrier” (FBMC) est utilisée pour les utilisateurs secondaires, alors que dans le cas des utilisateurs primaires, une modulation “Orthogonal Frequency Division Multiplexing”(OFDM) est adoptée. Ce choix est motivé par les raisons suivantes: l’OFDM est utilisée dans de nombreux systèmes primaires actuels large bande; ainsi lorsque l’OFDM est considérée au niveau de l’utilisateur primaire, une bande passante importante peut être réutilisée. Concernant le système secondaire, bien que l’OFDM ait été reconnue comme forme d’onde éligible aux systèmes de la RI, la modulation FBMC peut être une autre candidate capable de palier certains défauts de l’OFDM. En effet, comparée à l’OFDM,la modulation FBMC a l’avantage de réduire le niveau d’interférences de l’utilisateur secondairequi est induit par la différence de fréquence des oscillateurs locaux équipant les stations de base secondaires et les utilisateurs primaires. Pour annuler ces interférences,un précodage peut être inséré au niveau des stations de base secondaires. Par conséquent,nous proposons de calculer l’expression des interférences dues au systéme secondaire au niveau du récepteur primaire. A partir de ce résultat nous proposons d’annuler les interférences en utilisant la méthode “Zero Forcing Beamforming” (ZFBF) . Afin de confirmer l’efficacité du système proposé, nous le comparons avec un système fondé sur une RIutilisant une modulation OFDM à la fois au primaire et au secondaire.Toutefois, l’application de la méthode ZFBF dépend des canaux entre les stations de base secondaires et les utilisateurs primaires avec lesquels on souhaite s’orthogonaliser. Une estimation de canal est donc nécessaire. Pour ce faire, nous proposons de modéliser le canal par un processus autorégressif (AR) et d’aborder l’estimation du canal en utilisant une séquence d’apprentissage. Les signaux reçus, appelés aussi “observations”, sont perturbés par un bruit de mesure additif. / Cognitive radio (CR) has been proposed as a technolgy to improve the spectrum efficiency by giving an opportunistic access of the licensed-user spectra to unlicensed users. In this thesis, our purpose is to propose a specific scenario of CR and to present solutions to some related problems .or this purpose, we consider an overlay CR consisting of a primary macro-cell and cognitive small cells of cooperative secondary base stations (SBS). We suggst studying a hydbrid CR where a filter bank multicarrier (FBMC) is used for the secondary users (SU) whereas the primary users (PU) are based on orthogonal frequency diiision multiplexing (OFDM). This choice is motivated by the following reasons : as OFDM is used in many current wideband primary systems, an important bandwidth can be reused when OFDM is considered for the PU. Concerning the secondary system, although OFDM has been recognized as a condidate for CR systems, FBMC modulation can be another candidate that overcomes some OFDM drawbacks. Indeed, compared to OFDM, FBMC has the advantage of reducing the SU interference level tha is induced by the differences between the SBS and PU carrier frequency offsets (CFO). In order to cancel the interferences, a precoding can ben inserted at the SBS. Therefore, we propose to derive the interference expression due to SU at het PU receiver. Then, ero forcing beamforming (ZFBF) is considered to cancel the interferences. To confirm the efficiency of the proposed cheme, we make a comparative study with CR based on OFDM for both the PU and theSU. However, applying ZFBF depends on the channels between the SBS and the PU. A channel estimation is hence necessary. For this purpose, we propose to approximate the channel by an autoregressive process (AR) and to consider the channel estimation issue by using a training sequence. The received signals, also called the observations, are disturbed by an additive measurement noise. They can be : 1) additive and white. In that case, the AR paramters and the channel can be jointly estimated from the received noisy signal by using e recursive approache. Neverless, the corresponding state space representaion of the system is non-linear. In addition to existing methods that have been considered, we propose to carry out a complementary study by investigating the relevance of the quadrature Kalman filter (QKF) and the cubature Kalman filter (CKF). The, we compare them with other non-linear Kalman based approaches. 2) additive and colored. In that case, a parametric approach can be considered and based on a priori model of the noise. In our case, a moving average (MA) model is studie. Our approach operates as follows : firstly, the AR parameters are estimated by using the overdetermined high-order Yule-Walker (HOYN) equations. The variance of the AR-process driving process can be deduced by means of an orthogonal projection betweenn two types of etimates of AR-process correlation vectors. Then, the correlation sequence of th MA noise is estimated. Secondly, the MA parameters are obtained by using a new variant of the inner-outer factorization approache. We study the avantages and the limits of the proposed method. The, we compare it with existing algorithms such as the improved least square-colored noise (ILS-CN), the Yule-Walker ILS (YWILS) and the prediction error method (PEM). The proposed method is first evaluated with synthetic AR and MA processes and then is applied in the field of mobile communcation for channel estimation.
264

Ökad återvinning? En statistisk analys av två teoretiska vägar framåt! : Studenters syn på återvinningsfrågan

Hansson, Mats January 2008 (has links)
<p>Denna studie har som syfte att ge underlag för beslut om hur återvinningsföretag borde gå tillväga i sina försök att höja återvinningsgraden. För att kunna uträtta detta, kommer jag att undersöka Tonglets och Barrs teorier och rekommendationer. Jag kommer även att leta efter bevis som stödjer att det finns en bristande överensstämmelse mellan individers avsikter och deras beteende.</p> / <p>The aim of this study is to give basis for decisions concerning how recycling companies should go about in their efforts to increase the recycling level. In order to accomplish this, I’m going to investigate Tonglet’s and Barr’s theories and recommendations. I’m also going to look for evidence that supports that there’s a value-action gap.</p>
265

Impact of glucose uptake rate on recombinant protein production in Escherichia coli

Bäcklund, Emma January 2011 (has links)
Escherichia coli (E. coli) is an attractive host for production of recombinant proteins, since it generally provides a rapid and economical means to achieve high product quantities. In this thesis, the impact of the glucose uptake rate on the production of recombinant proteins was studied, aiming at improving and optimising production of recombinant proteins in E. coli. E. coli can be cultivated to high cell densities in bioreactors by applying the fed-batch technique, which offers a means to control the glucose uptake rate. One objective of this study was to find a method for control of the glucose uptake rate in small-scale cultivation, such as microtitre plates and shake flasks. Strains with mutations in the phosphotransferase system (PTS) where used for this purpose. The mutants had lower uptake rates of glucose, resulting in lower growth rates and lower accumulation of acetic acid in comparison to the wild type. By using the mutants in batch cultivations, the formation of acetic acid to levels detrimental to cell growth could be avoided, and ten times higher cell density was reached. Thus, the use of the mutant strains represent a novel, simple alternative to fed-batch cultures.   The PTS mutants were applied for production of integral membrane proteins in order to investigate if the reduced glucose uptake rate of the mutants was beneficial for their production. The mutants were able to produce three out of five integral membrane proteins that were not possible to produce by the wild-type strain. The expression level of one selected membrane protein was increased when using the mutants and the expression level appeared to be a function of strain, glucose uptake rate and acetic acid accumulation. For production purposes, it is not uncommon that the recombinant proteins are secreted to the E. coli periplasm. However, one drawback with secretion is the undesired leakage of periplasmic products to the medium. The leakage of the product to the medium was studied as a function of the feed rate of glucose in fed-batch cultivations and they were found to correlate. It was also shown that the amount of outer membrane proteins was affected by the feed rate of glucose and by secretion of a recombinant product to the periplasm. The cell surface is another compartment where recombinant proteins can be expressed. Surface display of proteins is a potentially attractive production strategy since it offers a simple purification scheme and possibilities for on-cell protein characterisation, and may in some cases also be the only viable option. The AIDA-autotransporter was applied for surface display of the Z domain of staphylococcal protein A under control of the aidA promoter. Z was expressed in an active form and was accessible to the medium. Expression was favoured by growth in minimal medium and it seemed likely that expression was higher at higher feed rates of glucose during fed-batch cultivation. A repetitive batch process was developed, where relatively high cell densities were achieved whilst maintaining a high expression level of Z. / QC 20110608
266

Macromolecular Matchmaking : Mechanisms and Biology of Bacterial Small RNAs

Holmqvist, Erik January 2012 (has links)
Cells sense the properties of the surrounding environment and convert this information into changes in gene expression. Bacteria are, in contrast to many multi-cellular eukaryotes, remarkable in their ability to cope with rapid environmental changes and to endure harsh and extreme milieus. Previously, control of gene expression was thought to be carried out exclusively by proteins. However, it is now clear that small regulatory RNAs (sRNA) also carry out gene regulatory functions. Bacteria such as E. coli harbor a large class of sRNAs that bind to mRNAs to alter translation and/or mRNA stability. By identifying mRNAs that are targeted by sRNAs, my studies have broadened the understanding of the mechanisms that underlie sRNA-dependent gene regulation, and have shed light on the impact that this type of regulation has on bacterial physiology. Control of gene expression often relies on the interplay of many regulators. This interplay is exemplified by our discovery of mutual regulation between the sRNA MicF and the globally acting transcription factor Lrp. Through double negative feedback, these two regulators respond to nutrient availability in the environment which results in reprogramming of downstream gene expression. We have also shown that both the transcription factor CsgD, and the anti-sigma factor FlgM, are repressed by the two sRNAs OmrA and OmrB, suggesting that these sRNAs are important players in the complex regulation that allow bacteria to switch between motility and sessility. Bacterial populations of genetically identical individuals show phenotypic variations when switching to the sessile state due to bistability in gene expression. While bistability has previously been demonstrated to arise from stochastic fluctuations in transcription, our results suggest that bistability possibly may arise from sRNA-dependent regulatory events also on the post-transcriptional level.
267

Numerical Conformal mappings for regions Bounded by Smooth Curves

Andersson, Anders January 2006 (has links)
Inom många tillämpningar används konforma avbildningar för att transformera tvådimensionella områden till områden med enklare utseende. Ett exempel på ett sådant område är en kanal av varierande tjocklek begränsad av en kontinuerligt deriverbar kurva. I de tillämpningar som har motiverat detta arbete, är det viktigt att dessa egenskaper bevaras i det område en approximativ konform avbildning producerar, men det är också viktigt att begränsningskurvans riktning kan kontrolleras, särkilt i kanalens båda ändar. Denna avhandling behandlar tre olika metoder för att numeriskt konstruera konforma avbildningar mellan ett enkelt standardområde, företrädesvis det övre halvplanet eller enhetscirkeln, och ett område begränsat av en kontinuerligt deriverbar kurva, där begränsningskurvans riktning kan kontrolleras, exakt eller approximativt. Den första metoden är en utveckling av en idé, först beskriven av Peter Henrici, där en modifierad Schwarz-Christoffel-avbildning avbildar det övre halvplanet konformt på en polygon med rundade hörn. Med utgångspunkt i denna idé skapas en algoritm för att konstruera avbildningar på godtyckliga områden med släta randkurvor. Den andra metoden bygger också den på Schwarz-Christoffel-avbildningen, och utnyttjar det faktum att om enhetscirkeln eller halvplanet avbildas på en polygon kommer ett område Q i det inre av dessa, som till exempel en cirkel med centrum i origo och radie mindre än 1, eller ett område i övre halvplanet begränsat av två strålar, att avbildas på ett område R i det inre av polygonen begränsat av en slät kurva. Vi utvecklar en metod för att hitta ett polygonalt område P, utanför det Omega som man önskar att skapa en avbildning för, sådant att den Schwarz-Christoffel-avbildning som avbildar enhetscirkeln eller halvplanet på P, avbildar Q på Omega. I båda dessa fall används tangentpolygoner för att numeriskt bestämma den önskade avbildningen. Slutligen beskrivs en metod där en av Don Marshalls så kallade zipper-algoritmer används för att skapa en avbildning mellan det övre halvplanet och en godtycklig kanal, begränsad av släta kurvor, som i båda ändar går mot oändligheten som räta parallella linjer. / In many applications, conformal mappings are used to transform two-dimensional regions into simpler ones. One such region for which conformal mappings are needed is a channel bounded by continuously differentiable curves. In the applications that have motivated this work, it is important that the region an approximate conformal mapping produces, has this property, but also that the direction of the curve can be controlled, especially in the ends of the channel. This thesis treats three different methods for numerically constructing conformal mappings between the upper half-plane or unit circle and a region bounded by a continuously differentiable curve, where the direction of the curve in a number of control points is controlled, exact or approximately. The first method is built on an idea by Peter Henrici, where a modified Schwarz-Christoffel mapping maps the upper half-plane conformally on a polygon with rounded corners. His idea is used in an algorithm by which mappings for arbitrary regions, bounded by smooth curves are constructed. The second method uses the fact that a Schwarz-Christoffel mapping from the upper half-plane or unit circle to a polygon maps a region Q inside the half-plane or circle, for example a circle with radius less than 1 or a sector in the half--plane, on a region Omega inside the polygon bounded by a smooth curve. Given such a region Omega, we develop methods to find a suitable outer polygon and corresponding Schwarz-Christoffel mapping that gives a mapping from Q to Omega. Both these methods use the concept of tangent polygons to numerically determine the coefficients in the mappings. Finally, we use one of Don Marshall's zipper algorithms to construct conformal mappings from the upper half--plane to channels bounded by arbitrary smooth curves, with the additional property that they are parallel straight lines when approaching infinity.
268

Mechanistic Studies on Ruthenium-Catalyzed Hydrogen Transfer Reactions

Åberg, Jenny B. January 2009 (has links)
Mechanistic studies on three different ruthenium-based catalysts have been performed. The catalysts have in common that they have been employed in hydrogen transfer reactions involving alcohols and ketones, amines and imines or both. Bäckvall’s catalyst, η5-(Ph5C5)Ru(CO)2Cl, finds its application as racemization catalyst in dynamic kinetic resolution, where racemic alcohols are converted to enantiopure acetates in high yields. The mechanism of the racemization has been investigated and both alkoxide and alkoxyacyl intermediates have been characterized by NMR spectroscopy and in situ FT-IR measurements. The presence of acyl intermediates supports a mechanism via CO assistance. Substantial support for coordination of the substrate during the racemization cycle is provided, including exchange studies with both external and internal potential ketone traps. We also detected an unexpected alkoxycarbonyl complex from 5-hydroxy-1-hexene, which has the double bond coordinated to ruthenium. Shvo’s catalyst, [Ru2(CO)4(μ-H)(C4Ph4COHOCC4Ph4)] is a powerful catalyst for transfer hydrogenation as well as for dynamic kinetic resolution. The mechanism of this catalyst is still under debate, even though a great number of studies have been published during the past decade. In the present work, the mechanism of the reaction with imines has been investigated. Exchange studies with both an external and an internal amine as potential traps have been performed and the results can be explained by a stepwise inner-sphere mechanism. However, if there is e.g. a solvent cage effect, the results can also be explained by an outer-sphere mechanism. We have found that there is no cage effect in the reduction of a ketone containing a potential internal amine trap. If the mechanism is outer-sphere, an explanation as to why the solvent cage effect is much stronger in the case of imines than ketones is needed. Noyori’s catalyst, [p-(Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3), has successfully been used to produce chiral alcohols and amines via transfer hydrogenation. The present study shows that the mechanism for the reduction of imines is different from that of ketones and aldehydes. Acidic activation of the imine was found necessary and an ionic mechanism was proposed.
269

Pojkar är starka, flickor är rosa. : En studie av leksaksreklam riktad till barn. / Boys are strong, girls are pink. : a study about toy advertising to children.

Kajdic, Admira, Pousar, Madeleine January 2013 (has links)
Syftet med denna uppsats är att kritiskt granska leksaksreklam riktad till barn. Genom att använda oss av reklamklipp från det sociala mediet YouTube vill vi undersöka hur manligt respektive kvinnligt samt heteronormativitet konstrueras i dessa. För att finna mönster som vi kan koppla till vårt syfte tittar vi ur ett genusperspektiv genom textanalys närmare på reklamklippen. Genom vår analys fann vi att leksaksreklam riktad till barn är påtaglig könsstereotyp och skapar förväntningar på barn hur de ska se ut samt vilka egenskaper de förväntas inneha. Vi fann också att reklamklippen reproducerar heterosexualiteten som den hegemoniska sexualiteten. Detta gör att heteronormativiteten blir stark i reklamklipen då samtliga reklamklipp riktade till flickor vi tittat på är byggda på en parrelation mellan en man och en kvinna. Nyckelord: Genus, heteronormativitet, maskulinitet, könsroller, leksaker, den inre och yttre sfären, arbetsdelningen, passiv och aktiv, rosa. / English title: Boys are strong, girls are pink - a study of toy advertising to children. The purpose of this study was to critically examine the toy advertising to children. Through the use of commercials from the social media YouTube, we wanted to examine how male or female and heteronormativity were socially constructed in them. Through text analysis, we looked closer at the commercials with a gender perspective in order to find patterns that we could connect to our purpose. Through our analysis we found that toy advertising to children is reproducing gender stereotypes creating expectations for children how they should look and what features they expected to hold. We also found that the commercials reproduce heterosexuality as the hegemonic sexuality, as all commercials aimed at girls we looked at reproduces the partnership between two individuals as a relationship between a man and a woman. Keywords: gender, heteronormativity, masculinity, gender roles, toys, the inner and outer sphere of labor, passive and active, pink.
270

Applicability of deterministic global optimization to the short-term hydrothermal coordination problem

Ferrer Biosca, Alberto 30 March 2004 (has links)
Esta Tesis esta motivada por el interés en aplicar procedimientos de optimización global a problemas del mundo real. Para ello, nos hemos centrado en el problema de Coordinación Hidrotérmica de la Generación Eléctrica a Corto Plazo (llamado Problema de Generación en esta Tesis) donde la función objetivo y las restricciones no lineales son polinomios de grado como máximo cuatro. En el Problema de Generación no tenemos disponible una representación en diferencia convexa de las funciones involucradas ni tampoco es posible utilizar la estructura del problema para simplificarlo. No obstante, cuando disponemos de una función continua f(x) definida en un conjunto cerrado y no vacío S el problema puede transformarse en otro equivalente expresado mediante minimize l(z) subject to z 2 D n int. (programa d.c. canónico), donde l(z) es una función convexa (en general suele ser una función lineal) con D y C conjuntos convexos y cerrados. Una estructura matemática tal como Dnint C no resulta siempre aparente y aunque lo fuera siempre queda por realizar una gran cantidad de cálculos para expresarla de manera que se pueda resolver el problema de una manera eficiente desde un punto de vista computacional.La característica más importante de esta estructura es que aparecen conjuntos convexos y complementarios de conjuntos convexos. Por este motivo en tales problemas se pueden usar herramientas analíticas tales como subdifernciales y hiperplanos soporte. Por otro lado, como aparecen conjuntos complementarios de conjuntos convexos, estas herramientas analíticas se deben usar de una manera determinada y combinándolas con herramientas combinatorias tales como cortes por planos, Branco and bound y aproximación interior.En esta tesis se pone de manifiesto la estructura matemática subyacente en el Problema de Generación utilizando el hecho de que los polinomios son expresables como diferencia de funciones convexas. Utilizando esta propiedad describimos el problema como un programa d.c. canónico equivalente. Pero aun mas, partiendo de la estructura de las funciones del Problema de Generación es posible rescribirlo de una manera mas conveniente y obtener de este modo ventajas numéricas desde elpunto de vista de la implementación.Basándonos en la propiedad de que los polinomios homogéneos de grado 1 son un conjunto de generadores del espacio vectorial de los polinomios homogéneos de grado m hemos desarrollamos los conceptos y propiedades necesarios que nos permiten expresar un polinomio cualquiera como diferencia de polinomios convexos, También, se ha desarrollado y demostrado la convergencia de un nuevo algoritmo de optimización global (llamado Algoritmo Adaptado) que permite resolver el Problema de Generación. Como el programa equivalente no esta acotado se ha introducido una técnica de subdivisión mediante prismas en lugar de la habitual subdivisión mediante conos.Para obtener una descomposición óptima de un polinomio en diferencia de polinomios convexos, se ha enunciado el Problema de Norma Mínima mediante la introducción del concepto de Descomposición con Mínima Desviación, con lo cual obtenemos implementaciones m´as eficientes, al reducir el n´umero de iteraciones del Algoritmo Adaptado. Para resolver el problema de Norma Mínima hemos implementado un algoritmo de programación cuadrática semi-infinita utilizando una estrategia de build-up and build-down, introducida por Den Hertog (1997) para resolver programas lineales semi-infinitos, la cual usa un procedimiento de barrera logarítmica.Finalmente, se describen los resultados obtenidos por la implementación de los algoritmos anteriormente mencionados y se dan las conclusiones. / This Thesis has been motivated by the interest in applying deterministic global optimization procedures to problems in the real world with no special structures. We have focused on the Short-Term Hydrothermal Coordination of Electricity Generation Problem (also named Generation Problem in this Thesis) where the objective function and the nonlinear constraints are polynomials of degree up to four. In the Generation Problem there is no available d.c. representation of the involved functions and we cannot take advantage of any special structure of the problem either. Hence, a very general problem, such as the above-mentioned, does not seem to have any mathematical structure conducive to computational implementations. Nevertheless, when f(x) is a continuous function and S is a nonempty closed set the problem can be transformed into an equivalent problem expressed by minimize l(z) subject to z 2 D n intC (canonical d.c. program), where l(z) is a convex function (which is usually a linear function) and D and C are closed convex sets. A mathematical complementary convex structure such as D n int C is not always apparent and even when it is explicit, a lot of work still remains to be done to bring it into a form amenable to efficient computational implementations. The attractive feature of the mathematicalcomplementary convex structure is that it involves convexity. Thus, we can use analytical tools from convex analysis like sub differential and supporting hyper plane.On the other hand, since convexity is involved in a reverse sense, these tools must be used in some specific way and combined with combinatorial tools like cutting planes, branch and bound and outer approximation.We introduce the common general mathematical complementary convex structure underlying in global optimization problems and describe the Generation Problem, whose functions are d.c. functions because they are polynomials. Thus, by using the properties of the d.c. functions, we describe the Generation Problem as an equivalent canonical d.c. programming problem. From the structure of its functions the Generation Problem can be rewritten as a more suitable equivalent reverse convex program in order to obtain an adaptation for advantageous numerical implementations.Concepts and properties are introduced which allow us to obtain an explicit representation of a polynomial as a deference of convex polynomials, based on the fact that the set of mth powers of homogeneous polynomials of degree 1 is a generating set for the vector space of homogeneous polynomials of degree m.We also describe a new global optimization algorithm (adapted algorithm) in order to solve the Generation Problem. Since the equivalent reverse convex program is unbounded we use prismatical subdivisions instead of conical ones. Moreover, we prove the convergence of the adapted algorithm by using a prismatical subdivision process together with an outer approximation procedure.We enounce the Minimal Norm Problem by using the concept of Least Deviation Decomposition in order to obtain the optimal d.c. representation of a polynomial function, which allows a more efficient implementation, by reducing the number of iterations of the adapted algorithm.A quadratic semi-infinite algorithm is described. We propose a build-up and down strategy, introduced by Den Hertog (1997) for standard linear programs that uses a logarithmic barrier method.Finally, computational results are given and conclusions are explained.

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