Energy Efficient Network Resource Allocation Scheme for Hose Model

Given the exponential growth in telecommunication networks, more and more attention is being paid to their energy consumption. However, the often over-provisioned　wired network is still overlooked. In core networks, pairs of routers are typically connected by multiple physical cables that form one logical bundled link participating in　the intra-domain routing protocol. To reduce the energy consumption of hose-model　networks with bundled cables, we propose a scheme to deactivate the maximum number　of cables, and associated equipment, possible. A similar approach has been presented　for the pipe model, where the exact traffic matrix is assumed to be known. Due to　traffic　uncertainty, however, it is difficult for operators to have exact knowledge of the　traffic matrix. This traffic uncertainty can be avoided by using the hose model, which　specifies only the upper bounds of the egress/ingress traffic from/to a node. We introduce a mixed integer linear problem formulation that yields the optimal solution and a more practical and near optimal heuristic algorithm for large networks. Our performance evaluation results show that it offers up to 50% power reduction compared to shortest path routing.電気通信大学201

エラスティック光ネットワークにおけるトラヒック収容性を向上させるための無瞬断デフラグメンテーション

In elastic optical networks (EONs), a major obstacle to using the spectrum resources efficiently is spectrum fragmentation. Much of the research activities in EONs focuses on finding defragmentation methods which remove the spectrum fragmentation. Among the defragmentation methods presented in the literature, hitless defragmentation has been introduced as an approach to limit the spectrum fragmentation in elastic optical networks without traffic disruption. It facilitates the accommodation of new request by creating large spectrum blocks, as it moves active lightpaths (retuning) to fill in gaps left in the spectrum by expired ones.　Nevertheless, hitless defragmentation witnesses limitations for gradual retuning with the conventionally used first fit allocation. The first fit allocation stacks all lightpaths to the lower end of the spectrum. This leads to a large number of lightpaths that need to be retuned and are subject to interfere with each other\u27s retuning. This thesis presents two schemes, which are based on hitless defragmentation, to increase the admissible traffic in EONs.　Firstly, a route partitioning scheme for hitless defragmentation in default EONs is presented. The proposed scheme uses route partitioning with the first-last fit allocation to increase the possibilities of lightpath retuning by avoiding the retuning interference among lightpaths. The first-last fit allocation is used to set a bipartition with one partition allocated with the first fit and the second with the last fit. Lightpaths that are allocated on different partitions cannot interfere with each other. Thus the route partitioning avoids the interferences among lightpaths when retuning. The route partitioning problem is defined as an optimization problem to minimize the total interferences.　Secondly, this thesis presents a defragmentation scheme using path exchanging in 1+1 path protected EONs. For 1+1 path protection, conventional defragmentation approaches consider designated primary and backup paths. This exposes the spectrum to fragmentations induced by the primary lightpaths, which are not to be disturbed in order to achieve hitless defragmentation. The presented path exchanging scheme exchanges the path function of the 1+1 protection with the primary toggling to the backup state while the backup becomes the primary. This allows both lightpaths to be reallocated during the defragmentation process while they work as backup, offering hitless defragmentation. Considering path exchanging, a static spectrum reallocation optimization problem that minimizes the spectrum fragmentation while limiting the number of path exchanging and reallocation operations is defined.　For each of the presented schemes, after the problem is defined as an optimization problem, it is then formulated as an integer linear programming problem (ILP). A decision version of each defined problem is proven NP-complete. A heuristic algorithm is then introduced for large networks, where the ILP used to represent the problem is not tractable. The simulation results show that the proposed schemes outperform the conventional ones and improve the total admissible traffic.電気通信大学201

エラスティック光ネットワークにおけるトラヒック収容性を向上させるための無瞬断デフラグメンテーション

In elastic optical networks (EONs), a major obstacle to using the spectrum resources efficiently is spectrum fragmentation. Much of the research activities in EONs focuses on finding defragmentation methods which remove the spectrum fragmentation. Among the defragmentation methods presented in the literature, hitless defragmentation has been introduced as an approach to limit the spectrum fragmentation in elastic optical networks without traffic disruption. It facilitates the accommodation of new request by creating large spectrum blocks, as it moves active lightpaths (retuning) to fill in gaps left in the spectrum by expired ones.　Nevertheless, hitless defragmentation witnesses limitations for gradual retuning with the conventionally used first fit allocation. The first fit allocation stacks all lightpaths to the lower end of the spectrum. This leads to a large number of lightpaths that need to be retuned and are subject to interfere with each other\u27s retuning. This thesis presents two schemes, which are based on hitless defragmentation, to increase the admissible traffic in EONs.　Firstly, a route partitioning scheme for hitless defragmentation in default EONs is presented. The proposed scheme uses route partitioning with the first-last fit allocation to increase the possibilities of lightpath retuning by avoiding the retuning interference among lightpaths. The first-last fit allocation is used to set a bipartition with one partition allocated with the first fit and the second with the last fit. Lightpaths that are allocated on different partitions cannot interfere with each other. Thus the route partitioning avoids the interferences among lightpaths when retuning. The route partitioning problem is defined as an optimization problem to minimize the total interferences.　Secondly, this thesis presents a defragmentation scheme using path exchanging in 1+1 path protected EONs. For 1+1 path protection, conventional defragmentation approaches consider designated primary and backup paths. This exposes the spectrum to fragmentations induced by the primary lightpaths, which are not to be disturbed in order to achieve hitless defragmentation. The presented path exchanging scheme exchanges the path function of the 1+1 protection with the primary toggling to the backup state while the backup becomes the primary. This allows both lightpaths to be reallocated during the defragmentation process while they work as backup, offering hitless defragmentation. Considering path exchanging, a static spectrum reallocation optimization problem that minimizes the spectrum fragmentation while limiting the number of path exchanging and reallocation operations is defined.　For each of the presented schemes, after the problem is defined as an optimization problem, it is then formulated as an integer linear programming problem (ILP). A decision version of each defined problem is proven NP-complete. A heuristic algorithm is then introduced for large networks, where the ILP used to represent the problem is not tractable. The simulation results show that the proposed schemes outperform the conventional ones and improve the total admissible traffic.電気通信大学201

Flows Reduction Scheme Using Two MPLS Tags in Software-Defined Network

This paper proposes a scheme to reduce the number of flow entries permanently stored in an OpenFlow switch and the number of configuration messages from a controller in a software-defined network (SDN). In an SDN, a flow table in an OpenFlow switch is used to instruct packets. The flow table consists of flow entries decided by the controller. A flow request is sent from the OpenFlow switch to the controller if the incoming packet does not match any flow entry in the flow table. The controller\u27s central processing unit may be overloaded to handle user requests, since the user requests for different data types have been rapidly increasing. As a result, flow configuration in switches is delayed. Moreover, the control plane may be flooded by configuration messages of those requests. A scheme to permanently keep the flow entries in the switch can reduce the number of requests. However, a large number of permanent flow entries is required. Other switch features may be degraded, since there is not enough memory in the flow table to implement those features. In the proposed scheme, switches in the network are divided into multiple regions. In order to guide packets from sources to destinations, the flow table incorporating the concept of two multiprotocol label switching tags is re-designed. One tag directs a packet from a source switch to an edge switch in the destination region. The other tag directs the packet from that edge switch to another switch in the same region. A mathematical model for the proposed scheme is formulated as an integer linear programming to determine a set of switches in each region so that the total number of permanent flow entries in the network can be minimized. The performance of the proposed scheme is analyzed. Moreover, the proposed scheme is implemented and demonstrated via Japanese Science Information Network 5

Hydrocephalie post-meningitique du nourrisson a Dakar

Introduction L’étiologie post-infectieuse de l’hydrocéphalie varie entre 7 et 48 % et reste corrélée au niveau de santé de la population du pays considéré. Elle en constitue la principale cause dans les pays sous-développés. Cependant cette prédominance des hydrocéphalies post-infectieuses à tendance à s’atténuer, surtout chez le nourrisson avec un profil étiologique qui tend vers celui des pays développés. Cette étude a pour objectif de déterminer les raisons de cette diminution.Matériel et méthodes Il s’agit d’une étude rétrospective de 2004 à 2008, portant sur 91 nourrissons traités pour hydrocéphalie. Parmi eux, 42 avaient une origine post-méningitique. Le diagnostic d’hydrocéphalie post-méningitique a été établi sur les antécédents de méningite, la bactériologie du LCR et sur l’imagerie (TDM, ETF).Résultats L’étiologie post-méningitique représentait 46% des hydrocéphalies. L’âge moyen était de 7,6 mois. La couverture vaccinale optimale était notée dans 7 cas. On notait une prédominance de la méningite à heamophilus influenza avec une forte proportion des méningites à bactériologie négative (30 cas). Nous avons retrouvé dans 32 cas une hydrocéphalie tétraventriculaire. A long terme, seuls 5 enfants ont eu un développement psychomoteur satisfaisant.Conclusion L’étiologie post-méningitique des hydrocéphalies reste fréquente en dépit des efforts entrepris dans le domaine de la prévention. Mais beaucoup de progrès reste à faire dans son renforcement et dans la prise en charge précoce des méningites

Réduction des coûts alimentaires des lapins (Oryctolagus cuniculus L.) par la distribution de l'herbe de lait (Euphorbia heterophylla (L.) Klotz. & Garcke) associée à l'herbe de Guinée (Panicum maximum Jacq.) Lam...

Full French Title: Réduction des coûts alimentaires des lapins (Oryctolagus cuniculus L.) par la distribution de l'herbe de lait (Euphorbia heterophylla (L.) Klotz. & Garcke) associée à l'herbe de Guinée (Panicum maximum Jacq.) Lam. en élevage semi-intensifObjectif: Le présent travail vise à comparer l'effet de deux modes de supplémentation par Euphorbia heterophylla d'un régime à base d'un aliment concentré sur les paramètres d'ingestion et de croissance des lapins et sur les charges alimentaires nécessaires à la production d'un kilogramme de carcasse.Méthodologie et Résultats: Le premier mode (MOD1) a consisté à supplémenter le régime témoin (MOD0) durant les trois mois de vie des lapins. Le second mode a consisté à distribuer le supplément seulement durant la phase d’engraissement de 30 jours (MOD2). Les poids et le rendement carcasse à 3 mois d’âge, étaient de 2117,6±282 g, 1650,6±110,4 g et de 1693,2±116,9 g puis de 57,1±0,7%, 51,8±1,6% et de 56,8±1,2% respectivement pour MOD0, MOD1 et MOD2. MOD2 a induit un meilleur rendement carcasse des lapins (P<0,05). Cependant, MOD1 a induit une réduction de 26 % des charges alimentaires par rapport au MOD0.Conclusion et Application des résultats: Les résultats de cette étude permettent de conclure que Euphorbia heterophylla peut être recommandée comme supplément alimentaire dans l'élevage des lapins lorsqu'elle est disponible.Mots clés: Lapin, fourrage, Euphorbia heterophylla, Panicum maximum, croissance, carcasseEnglish Title: Reduction of rabbit food costs (Oryctolagus cuniculus L.) by distribution of milkweed (Euphorbia heterophylla) associated to Guinea grass (Panicum maximum Jacq.) Lam. in semi-intensive livestockEnglish AbstractObjective: The aim of this study was to compare the effect of two methods of supplementation by Euphorbia heterophylla of a commercial based feed on ingestion and growth parameters of rabbits and on food expenses for the production of a carcass kilogram.Methodology and Results: The first mode (MOD1) consisted in the supplementation of the control diet (MOD0) during the three months of life of the rabbits. In the second one, it consisted in the distribution of the supplement only during the final 30 days of fattening (MOD2). Body weight and carcass yield at 3 months of age, were 2117.6±282 g, 1650.6±110.4 g and 1693.2±116.9 g then 57.1±0.7%, 51.8±1.6% and 56.8±1.2% respectively for MOD0, MOD1 and MOD2. MOD2 induced a better carcass yield of rabbits (P<0.05). However, MOD1 induced 26% of reduction of food expenses compared to MOD0.Conclusions and Application of Results: This study indicated that Euphorbia heterophylla could be recommended as a dietary supplement where it is present.Keywords: Rabbit, feed, Euphorbia heterophylla, Panicum maximum, growth, carcas

Prise en charge de l’hematome extradural a Dakar. A propos de 40 cas

Introduction L’hématome extradural est une affection rare mais grave car engage rapidement le pronostic vital. Il s’agit d’une urgence thérapeutique nécessitant par conséquent une prise en charge rapide.Objectif L’objectif de ce travail est d’évaluer les aspects épidémiologiques, diagnostiques et thérapeutiques de l’hématome extradural depuis l’avènement du scanner dans notre pays.Patients et méthode Il s’agit d’une étude rétrospective multicentrique réalisée dans quatre de nos hôpitaux durant une période de huit ans, de juillet 1994 à juin 2002. Nous avons pu collecter 40 dossiers de patients traumatisés cranioencéphaliques présentant un hématome extradural à la tomodensitométrie cérébrale.Résultats Sur 1296 patients ayant consulté pour un traumatisme cranio-encéphalique toute gravité confondue, 40 ont présenté un hématome extra dural soit 3,09%. L’age moyen était de 26.1 ans avec une fréquence maximale entre 11 et 20 ans. Le sex. Ratio est de 9.1. Les accidents de la voie publique représentent l’étiologie la plus fréquente avec 55% des cas. Le délai de consultation est long avec une moyenne de 2 à 3 jours. L’examen clinique retrouve des signes d’hypertension intracrânienne chez 87,5% des patients, un déficit moteur chez 30% des patients, des troubles de la conscience dans 55% des cas. Les résultats scannographiques ont montré une localisation temporo pariétale prédominante (72,5%) . 87,5% des patients ont bénéficié d’une prise en charge chirurgicale. L’évolution est favorable dans 75% des cas. Nous avons noté 20% de mortalité.Conclusion L’hématome extradural constitue l’urgence neurochirurgicale type. Son pronostic est bon si traité précocement