Exploiting Global Constraints for Search and Propagation

Résumé Cette thèse se concentre sur la Programmation par contraintes (PPC), qui est un paradigme émergent pour résoudre des problèmes complexes d’optimisation combinatoire. Les principales contributions tournent autour du filtrage des contraintes et de la recherche; les deux sont des composantes cl´e dans la résolution de problèmes complexes à travers la PPC. D’un côté, le filtrage des contraintes permet de réduire la taille de l’espace de recherche, d’autre part, la recherche définit la manière dont cet espace sera exploré. Les progrès sur ces sujets sont essentiels pour élargir l’applicabilité de CP à des problèmes réels. En ce qui concerne le filtrage des contraintes, les contributions sont les suivantes: premièrement, on propose une amélioration sur un algorithme existant de la version relaxée d’une contrainte commune qui apparaît souvent dans les problèmes d’affectation (soft gcc). L’algorithme proposé améliore en termes de complexité soit pour la cohérence, soit pour le filtrage et en termes de facilité d’implémentation. Deuxièmement, on introduit une nouvelle contrainte (soit dure soit relaxée) et les algorithmes de filtrage pour une sous-structure récurrente qui se produit dans les problèmes d’affectation des ressources hétérogènes (hierarchical gcc). Nous montrons des résultats encourageants par rapport à une d´écomposition équivalente basée sur gcc. En ce qui concerne la recherche, nous présentons tout d’abord les algorithmes pour compter le nombre de solutions pour deux importantes familles de contraintes: les contraintes sur les occurrences, par exemple, alldifferent, symmetric alldifferent et gcc, et les contraintes de séquence admissible, telles que regular. Ces algorithmes sont à la base d’une nouvelle famille d’heuristiques de recherche, centrées sur les contraintes et basées sur le d´énombrement. Ces heuristiques extraient des informations sur le nombre de solutions des contraintes, pour guider la recherche vers des parties de l’espace de recherche qui contiennent probablement un grand nombre de solutions. Les résultats expérimentaux sur huit différents problèmes montrent une performance impressionnante par rapport à l’état de l’art des heuristiques génériques. Enfin, nous expérimentons une forme forte, déjà connue, de filtrage qui est guidée par la recherche (quick shaving). Cette technique donne des résultats soit encourageants soit mauvais lorsqu’elle est appliquée aveuglément à tous les problèmes. Nous avons introduit un estimateur simple mais très efficace pour activer ou désactiver dynamiquement le quick shaving; de tests expérimentaux ont montré des résultats très prometteurs.----------Abstract This thesis focuses on Constraint Programming (CP), that is an emergent paradigm to solve complex combinatorial optimization problems. The main contributions revolve around constraint filtering and search that are two main components of CP. On one side, constraint filtering allows to reduce the size of the search space, on the other, search defines how this space will be explored. Advances on these topics are crucial to broaden the applicability of CP to real-life problems. For what concerns constraint filtering, the contribution is twofold: we firstly propose an improvement on an existing algorithm of the relaxed version of a constraint that frequently appears in assignment problems (soft gcc). The algorithm proposed outperforms the previously known in terms of time-complexity both for the consistency check and for the filtering and in term of ease of implementiation. Secondly, we introduce a new constraint (both hard and soft version) and associated filtering algorithms for a recurrent sub-structure that occurs in assignment problems with heterogeneous resources (hierarchical gcc). We show promising results when compared to an equivalent decomposition based on gcc. For what concerns search, we introduce algorithms to count the number of solutions for two important families of constraints: occurrence counting constraints, such as alldifferent, symmetric alldifferent and gcc, and sequencing constraints, such as regular. These algorithms are the building blocks of a new family of search heuristics, called constraint-centered counting-based heuristics. They extract information about the number of solutions the individual constraints admit, to guide search towards parts of the search space that are likely to contain a high number of solutions. Experimental results on eight different problems show an impressive performance compared to other generic state-of-the-art heuristics. Finally, we experiment on an already known strong form of constraint filtering that is heuristically guided by the search (quick shaving). This technique gives mixed results when applied blindly to any problem. We introduced a simple yet very effective estimator to dynamically disable quick shaving and showed experimentally very promising results

An Overview of Ripening Processes

The chapter aims to address an overview of the new discoveries regarding the methods of ripening processes. The chapter presents the latest methods used in fruit and vegetable ripening processes, ripening processes in the food industry, enzymatic ripening processes, and artificial ripening processes. Nowadays everyone wants all kinds of food to be available in every season. Naturally, we find fruits and vegetables in their ripening season, but in order to provide the population with fruit out of season, we import them from different countries, which are not harvested at full maturity, and different adjuvant ripening methods are used. Processed foods are also subjected to ripening processes, the most used being cheese and meat products. These foods are some of the most valued foods nowadays, they are considered luxury products with superior nutritional and taste properties. To achieve these ripening processes, enzymatic processes or artificial ripening are also involved. The purpose of using these processes is to provide consumers with fresh out-of-season food or food with a high degree of sensory and nutritional properties, and at the same time with a superior degree of quality and safety, because the safety of the consumer comes first

Evaluation of Alternative Technologies to Supply Drinking Water to Marines in Forward Deployed Locations

With recent increases, there are approximately 20,000 Marines deployed in the Helmand Province of Afghanistan. The cost of delivering bottled water to the troops is rapidly becoming unsustainable and convoys delivering bottled water are vulnerable to Improvised Explosive Devices (IEDs). Currently, raw water from indigenous sources, which has chemical and microbiological contaminants, is treated with reverse osmosis (RO), but only used for hygiene, with bottled water used for drinking. Due to the economic costs and risks to life of providing bottled water, decision-makers need to evaluate technology alternatives to treat raw water to supply safe drinking water. In this study, an innovative decision analysis tool, Choosing by Advantages (CBA), was used to evaluate and select the best alternative water treatment technology to support Marines in Afghanistan. Using criteria developed by a panel of experts, the CBA method was applied to determine that the best alternative technology is a treatment train: ultrafiltration pretreatment, RO treatment, and electrodeionization post treatment. This treatment train would produce high quality water and lower overall RO energy consumption, operation and maintenance costs, and reduce the replacement frequency of RO membranes

The Role of Salt on Food and Human Health

Throughout time, salt (sodium chloride) played an important role in human societies. In ancient times, salt was used as a form of currency and to preserve foods, such as meat and fish. Besides, salt also assumed a major importance as food flavour enhancer. However, excessive salt consumption could result in serious health problems, related with hypertension and cardiovascular diseases, although this might be a controversial topic in the near future. The World Health Organization has made several policy recommendations to reduce salt intake and even implemented some policy approaches in several countries worldwide. Nevertheless, according to the European Food Safety Authority, approximately 75% of the salt we eat is already in the foods we buy. Thus, the best way to assure an effective reduction in salt consumption is to train our taste to the flavour of low-salt foods, although there is still a long way to go from awareness to action. The main goal of this chapter is to review the social and economic importance of salt throughout human history; its role in food preservation, food safety and food sensory evaluation; the impact of salt intake on human health; and the attempts to reduce or replace salt in food

When Can Oil Economies Be Deemed Sustainable?

This open access book questions the stereotype depicting all Gulf (GCC) economies as not sustainable, and starts a critical discussion of what these economies and polities should do to guarantee themselves a relatively stable future. Volatile international oil markets and the acceleration of the energy transition has challenged the notion that oil revenues are sufficient to sustain oil economies in the near to medium term. But what is the meaning of economic sustainability? The book discusses the multiple dimensions of the concept: economic diversification, continuing value of resources, taxation and fiscal development, labor market sustainability, sustainable income distribution, environmental sustainability, political order (democracy or authoritarianism) and sustainability, regional integration. The overarching message in this book is that we should move on from the simplistic branding of the Gulf economies as unsustainable and tackle the details of which adaptations they might need to undertake

Understanding the role of state identity in foreign policy decision-making: the rise of Saudi-Iranian rapprochement (1997-2009)

The objective of the thesis is to study the concept of state identity and its role in foreign policy decision-making through a constructivist analysis, with particular focus on the Saudi–Iranian rapprochement of 1997. While there has been a recent growth in the study of ideational factors and their effects on foreign policy in the Gulf, state identity remains understudied within mainstream International Relations (IR), Foreign Policy Analysis (FPA), and even Middle Eastern studies literature, despite its importance and manifestation in the region’s foreign policy discourses. The aim is to challenge purely realist and power-based explanations that have dominated the discourse on Middle Eastern foreign policy—and in particular, the examination of Saudi–Iranian relations. Saudi Arabia and Iran have played key roles in Gulf security for the past four decades, yet there have been few studies addressing their bilateral relations. Traditionally, differences—including sectarianism, nationalism, revolutionary ideology, competition over regional hegemony, oil prices, policy towards US military presence in the Gulf, and disagreements over the hajj—are often cited as reasons for their rivalry, yet these differences do not on their own offer a convincingly clear explanation as to why the rapprochement took place at that particular time, or why it thrived—and subsequently declined—despite the continuing presence of these issues. The primary purpose of the thesis is to analyse and understand the reasons behind the rise and demise of the Saudi–Iranian rapprochement of 1997. By focusing on ideational and materialist factors, the thesis seeks to demonstrate how changes in state identity—particularly in the official foreign policy discourse—indicates changes in policy, and therefore a shift in the amity–enmity pattern between the two states. Without discarding the value of realist explanations, the thesis will argue that the rapprochement process of 1997 has been significantly (though not exclusively) influenced by changes in state identity in each state. Moreover, this thesis provides a theoretical framework based on the concept of state identity and role theory (“self versus other”) to study the evolution of enmity, the rise of the rapprochement process during the Khatami presidency (1997–2005), and the subsequent revival of Saudi–Iranian rivalry during President Ahmadinejad’s first term (2005–2009). The main argument of this thesis is that ideational and materialist factors were instrumental in the demise of the rapprochement process, but the change in Iran’s state identity during the first term of President Ahmadinejad altered the perception of each state towards the other. Thus, the relationship transformed from a state of relative friendliness to a state of enmity and rivalry. This is explained by examining the muqawama–mumana’a discourse and the “moderates” versus “radicals” debate that consumed the narrative of Saudi–Iranian relations between 2005 and 2009. The methods employed in answering these research questions and hypotheses are largely structured around a chronological account of the development and formation of state identities and an analysis of each state’s foreign policy discourse during the period in question. This will be supplemented by qualitative interviews with individuals who participated in the rapprochement process, and will draw upon new archival material that has hitherto not been utilised in the literature on this subject

Genetic mapping of fruit quality traits in apple (malus x domestica borkh.)

Philosophiae Doctor - PhDApple fruit quality is of utmost importance to apple farmers and breeders in the selection and commercialization of new cultivars. Fruit size, colour, texture, firmness and taste are all traits that affect the quality of fruit. In this study the genetic contribution of these traits, and others were evaluated in order to generate the genetic markers required for the application of marker assisted selection in fruit quality breeding. Three mapping populations, ‘Prima’ x ‘Anna’, ‘Golden Delicious’ x ‘Priscilla’ and ‘Golden Delicious’ x ‘Anna’, consisting of 87, 87 and 141 respectively, were used in the study. Fruit samples were analysed, using a range of visual, physical and sensory measurements, over a period of three years, and the data was then correlated using statistical analysis. Traits analysed included stripe-ness, fruit colour, fruit size, fruit form, ground colour, russet, texture, fruit firmness, juiciness, sugar content, acidity, taste, skin toughness, %TSS, fruit mass and diameter. ANOVA detected significant levels of variation between the three families for all traits except taste and russet; while highly significant ‘within family’ variation was also observed for all traits in pre- and post-storage analyses, except for sugar content (sweetness) and fruit form. Within family variation also contributed the largest percentage towards the variance components of all traits. Heritability estimates found stripe-ness to be the most heritable trait, from subjective analyses, while heritability values ranged from 0.41 to 0.84 for instrumentally measured traits. The genetic maps for the three populations were generated using both published microsatellites and new EST-SSR and DART markers, using JoinMap 4.0". The integrated genetic linkage maps of ‘Prima’ x ‘Anna’, ‘Golden Delicious’ x ‘Priscilla’, ‘Golden Delicious’ x ‘Anna’ consisted of 398 (133 SSR and 265 DArT), 353 (80 SSR and 273 DArT) and 213 (87 SSR and 126 DArT) markers respectively. The maps were 1021.6cM, 1079cM and 1302.7cM in length, respectively. Location of quantitative trait loci (QTL) for 14 fruit quality traits was detected using MapQTL 5.0" and a total of 79 pre-storage and 60 poststorage QTLs were identified on the three mapping populations. Comparative genome analysis and the role of various genes on the outcome of fruit quality can now be investigated. Using the integrated genetic maps, and the QTLs identified, candidate markers associated with these QTL can be used for marker-assisted selection, to increase the speed and efficiency of the apple breeding program