Planning Solar in Energy-managed Cellular Networks

There has been a lot of interest recently on the energy efficiency and environmental impact of wireless networks. Given that the base stations are the network elements that use most of this energy, much research has dealt with ways to reduce the energy used by the base stations by turning them off during periods of low load. In addition to this, installing a solar harvesting sys- tem composed of solar panels, batteries, charge con- trollers and inverters is another way to further reduce the network environmental impact and some research has been dealing with this for individual base stations. In this paper, we show that both techniques are tightly coupled. We propose a mathematical model that captures the synergy between solar installation over a network and the dynamic operation of energy-managed base stations. We study the interactions between the two methods for networks of hundreds of base stations and show that the order in which each method is intro- duced into the system does make a difference in terms of cost and performance. We also show that installing solar is not always the best solution even when the unit cost of the solar energy is smaller than the grid cost. We conclude that planning the solar installation and energy management of the base stations have to be done jointly

Planification et gestion de réseaux cellulaires avec énergie solaire

RÉSUMÉ Ce mémoire vise à étudier deux stratégies pour réduire les gaz à e˙et de serre dans les réseaux de télécommunications cellulaires : l’installation de panneaux solaires sur les stations de base et l’allocation dynamique des usagers aux stations. Les panneaux solaires permettent le remplacement énergétique par une énergie verte, ce qui réduira les gaz à effet de serre alors que l’allocation dynamique permet de mettre en veille certaines stations à certains moments de la journée, ce qui réduit la consommation énergétique. L’objectif principal de ce mémoire est de déterminer les interactions qu’il peut y avoir entre l’utilisation de l’énergie solaire et la gestion des stations de base. Pour répondre à cet objectif, deux modèles de réseau avec alimentation hybride ont été développés. Le premier modèle optimise l’énergie dans le réseau en considérant que la charge des usagers est constante à travers les années. La fonction objectif à minimiser est la somme du coût de capital des équipements solaires et du coût d’énergie pour l’opération du réseau. L’étude de ce modèle porte principalement sur l’interaction entre l’installation du solaire et la mise en veille dynamique des stations de base. On conclut qu’il y a une interaction marquée entre l’utilisation de l’énergie solaire et la gestion dynamique avec mode veille des stations du réseau. Plus particulièrement, l’ordre dans lequel chacune des méthode est introduite dans le réseau va avoir une influence sur les performances et son coût optimal. Le deuxième modèle permet, entre autres, d’avoir une croissance du trafic de données au fil des années. Ce modèle sert à étudier l’ajout de l’équipement solaire dans un réseau où il faut aussi rajouter des stations de base. On conclut avec ce deuxième modèle qu’il est important de repousser le plus tard possible l’installation de nouvelles stations peu importe qu’il y ait du solaire ou non.----------ABSTRACT The research done in this master’s thesis has the goal to diminish greenhouse gases in cellular telecommunications networks. This is done by adding solar equipment to dynamic networks where base stations can be turned o˙. Two mathematical models that capture the synergy between solar installation over a network and the dynamic operation of energy-managed base stations are presented. The first model optimizes the energy management in a network where the users’ load is constant through the years. The objective to be minimized is the sum of the capital cost needed for the solar equipment plus the cost of energy obtained from the electric grid. This model gives us insights on the synergy between planning of solar equipment in the network and switching o˙ the base stations. Notably, it is shown that the order in which these technologies are introduced makes a significant difference to the optimized objective function cost. Thus, this model emphasizes the fact that there is a strong correlation between the solar installation and the management of the base stations. Another result is that the solar equipment is not installed on every base station, even when the cost of solar energy is smaller than the cost of the grid. The second model optimizes a network where traÿc grows every year. This means that the model has to install new base stations and decide where to install them. Furthermore, the base stations now have different levels of transmission power instead of just being on or o˙. Finally, the functionality to install di˙erent kinds of solar equipment with different sizings is added. This complexity makes this model a lot more complex to solve and smaller networks are thus used. It is concluded that planning the installation of base stations throughout the years is much more important to reduce the total cost than installing solar

Integrated optimization of strategic and tactical planning decisions in forestry

The traditional approach to plan the forest products value chain using a combination of sequential and hierarchical planning phases leads to suboptimal solutions. We present an integrated planning model to support forest planning on the long term with anticipation of the impacts on the economic and logistic activities in the forest value chain on a shorter term, and we propose a novel optimization approach that includes acceleration strategies to efficiently solve large-scale practical instances of this integrated planning problem. Our model extends and binds the models implemented in two solver engines that have developed in previous work. The first system, called Logilab, allows for defining and solving value chain optimization problems. The second system, called Silvilab, allows for generating and solving strategic problems. We revisit the tactical model in Logilab and we extend the strategic model in Silvilab so that the integrated planning problem can be solved using column generation decomposition with the subproblems formulated as hypergraphs and solved using a dynamic programing algorithm. Also, a new set of spatial sustainability constraints is considered in this model. Based on numerical experiments on large-scale industrial cases, the integrated approach resulted in up to 13% profit increase in comparison with the non-integrated approach. In addition, the proposed approach compares advantageously with a standard LP column generation approach to the integrated forest planning problem, both in CPU time (with an average 2.4 factor speed-up) and in memory requirement (with an average reduction by a factor of 20)

Planning solar in energy-managed cellular networks

Recently, there has been a lot of interest on the energy efficiency and environmental impact of wireless networks. Given that the base stations are the network elements that use most of this energy, much research has dealt with ways to reduce the energy used by the base stations by turning them off during periods of low load. In addition to this, installing a solar harvesting system made up of solar panels, batteries, charge controllers, and inverters is another way to further reduce the network environmental impact, and some research has been dealing with this for individual base stations. In this paper, we show that both techniques are tightly coupled. We propose a mathematical model that captures the synergy between solar installation over a network and the dynamic operation of energy-managed base stations. We study the interactions between the two methods for networks of hundreds of base stations and show that the order in which each method is introduced into the system does make a difference in terms of cost and performance. We also show that installing solar is not always the best solution even when the unit cost of the solar energy is smaller than the grid cost. We conclude that planning the solar installation and energy management of the base stations has to be done jointly

Actes du 12e Colloque annuel des étudiant-e-s de cycles supérieurs du CRISES

La 12e édition du Colloque annuel des étudiant-e-s de cycles supérieurs du CRISES s’est tenue les 25 et 26 mars 2010 à l’Université Laval. Trente et une (31) communications y ont été présentées sur des thèmes aussi diversifiés que le Vieillissement au travail, les Grappes industrielles, l’Immigration, les Défis de la gouvernance, la Gestion des ressources et les solidarités locales, incluant un atelier spécial sur les Avancées et les limites de l’innovation sociale. Les textes qui nous sont parvenus avant la date limite du 18 mars afin d’être soumis à un processus d’évaluation, ainsi que respectivement le texte et/ou les diapositives PowerPoint des conférenciers d’ouverture et de clôture sont contenus dans ces Actes. Nous tenons ici à remercier chaleureusement nos collègues du comité organisateur : Kamel Béji, Manon Boulianne et Frédéric Hanin et notre assistante : Carole-Anne Gauthier."VIEILLISSEMENT AU TRAVAIL" "APPROCHES DE LA GOUVERNANCE" "GRAPPES INDUSTRIELLES ET DÉVELOPPEMENT LOCAL" "GESTION DES RESSOURCES" "SOLIDARITÉS LOCALES" "IMMIGRATION ET IDENTITÉ" "L'INNOVATION SOCIALE: AVANCÉES ET LIMITES

Potential biological role of poly (ADP-ribose) polymerase (PARP) in male gametes

Maintaining the integrity of sperm DNA is vital to reproduction and male fertility. Sperm contain a number of molecules and pathways for the repair of base excision, base mismatches and DNA strand breaks. The presence of Poly (ADP-ribose) polymerase (PARP), a DNA repair enzyme, and its homologues has recently been shown in male germ cells, specifically during stage VII of spermatogenesis. High PARP expression has been reported in mature spermatozoa and in proven fertile men. Whenever there are strand breaks in sperm DNA due to oxidative stress, chromatin remodeling or cell death, PARP is activated. However, the cleavage of PARP by caspase-3 inactivates it and inhibits PARP's DNA-repairing abilities. Therefore, cleaved PARP (cPARP) may be considered a marker of apoptosis. The presence of higher levels of cPARP in sperm of infertile men adds a new proof for the correlation between apoptosis and male infertility. This review describes the possible biological significance of PARP in mammalian cells with the focus on male reproduction. The review elaborates on the role played by PARP during spermatogenesis, sperm maturation in ejaculated spermatozoa and the potential role of PARP as new marker of sperm damage. PARP could provide new strategies to preserve fertility in cancer patients subjected to genotoxic stresses and may be a key to better male reproductive health

Extending the classic wood supply model to anticipate industrial fibre consumption

The classic wood supply optimisation model maximises even-flow harvest levels, and implicitly assumes infinite fibre demand. In many jurisdictions, this modelling assumption is a poor fit for actual fibre consumption, which is often a species-unbalanced subset of total fibre allocation. Failure to anticipate this bias in volume and species mix of industrial wood fibre consumption has been linked to increased risk of wood supply failure. In particular, we examine the distributed wood supply planning problem, which is a variant of the general wood supply planning problem where the roles of forest owner and fibre consumer are played by independent agents (e.g. wood supply planning on public forest land in Canada, where government stewards control wood supply and forest products industry firms consume the fibre). We use agency theory to describe the source of antagonism between public forest land owners (the principal) and industrial fibre consumers (the agent). We show that the distributed wood supply planning problem can be modelled more accurately using a bilevel formulation, and present an extension of the classic wood supply optimisation model which explicitly anticipates industrial fibre consumption behaviour. The general case of the bilevel wood supply optimisation problem is NP-hard, non-linear, and non-convex-it is difficult to solve to global optimality. By imposing certain restrictions on agent network topology, we show that the general case can be decomposed into convex sub-problems. We present a solution methodology that can solve this special case to global optimality, and compare output and solution times of classic and bilevel model formulations using a computational experiment on a realistic dataset. Experimental results show that solution time for the bilevel problem is comparable to solution time for the classic single-level problem, and that the bilevel formulation can mitigate risk of wood supply failure

A Bilevel Model Formulation for the Distributed Wood Supply Planning Problem

The classic wood supply optimisation model maximises even-flow harvest levels, and implicitly assumes infinite fibre demand. In many jurisdictions, this modelling assumption is a poor fit for actual fibre consumption, which is typically a subset of total fibre allocation. Failure of the model to anticipate this bias in industrial wood fibre consumption has been linked to increased risk of wood supply failure. In particular, we examine the distributed wood supply planning problem where the roles of forest owner and fibre consumer are played by independent agents. We use game theory to frame interactions between public forest land managers and industrial fibre consumers. We show that the distributed wood supply planning problem can be modelled more accurately using a bilevel formulation, and present an extension of the classic wood supply optimisation model which explicitly anticipates industrial fibre consumption behaviour. We present a solution methodology that can solve a convex special case of the problem to global optimality, and compare output and solution times of classic and bilevel model formulations using a computational experiment on a realistic dataset. Experimental results show that the bilevel formulation can mitigate risk of wood supply failure.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

On the risk of systematic drift under incoherent hierarchical forest management planning

In theory, linkages between hierarchical forest management planning levels ensure coherent disaggregation of long-term wood supply allocation as input for short-term demand-driven harvest planning. In practice, these linkages may be ineffective, and solutions produced may be incoherent in terms of volume and value-creation potential of harvested timber. Systematic incoherence between planned and implemented forest management activities may induce drift of forest system state (i.e., divergence of planned and actual system state trajectories), thus compromising credibility and performance of the forest management planning process. We describe hierarchical forest management from a game-theoretic perspective and present an iterative two-phase model simulating interaction between long- and short-term planning processes. Using an illustrative case study, we confirm the existence of a systematic drift effect, which we attribute to ineffective linkages between long- and short-term planning. In several simulated scenarios, the planning process fails to ensure long-term wood supply sustainability, fails to reliably meet industrial fiber demand over time, and exacerbates incoherence between wood supply and fiber demand over several planning iterations. We show that manipulating linkages between long- and short-term planning processes can reduce incoherence and describe future work on game-theoretic planning process model formulations that may improve hierarchical planning process performance.En théorie, les systèmes de planification hiérarchiques intègrent des mécanismes de liaison efficaces, assurant ainsi une désaggrégation cohérente de l'attribution de volumes aux usines lors de la planification détaillée des opérations de récolte. En pratique, les mécanismes de liaison entre la planification a` long- et a` court-terme peuvent être inefficaces, menant donc a` des plans incohérents en termes du volume récolté, de la représentation des essences, et du potentiel de création de valeur des billes livrées aux usines. Cette incohérence entre la planification et l'exécution de la récolte peut induire une dérive systématique de l'état du système forestier (c.-a`-d. divergence entre les trajectoires projetées et réalisées), compromettant donc la crédibilité et la performance du processus de planification de l'aménagement forestier. Nous décrivons le processus de planification forestière en termes de la théorie du jeu, et nous simulons l'interaction entre la planification de l'approvisionnement et la planification de la récolte a` l'aide d'un modèle itératif a` deux phases. Nous présentons une étude de cas, et nous montrons l'existence d'un effet de dérive systématique, que nous attribuons a` l'innefficacité des mécanismes reliant la planification long- et court-terme. Nous montrons qu'il est possible d'améliorer la cohérence des plans en manipulant les mécanismes de liaison, et proposons des avenues de recherche futures pouvant potentiellement améliorer la performance du processus de planification hiérarchique a` l'aide de nouvelles formulations de modèles basés sur la théorie du jeu