Optimal Ordering and Trade Credit Policy for EOQ Model

Trade credit is the most prevailing economic phenomena used by the suppliers for encouraging the retailers to increase their ordering quantity. In this article, an attempt is made to derive a mathematical model to find optimal credit policy and hence ordering quantity to minimize the cost. Even though, credit period is offered by the supplier, both parties (supplier and retailer) sit together to agree upon the permissible credit for settlement of the accounts by the retailer. A numerical example is given to support the analytical arguments.Trade Credit, Optimal ordering quantity, Lot-size

DiG: Data centers in the Grid

Demo abstract at IEEE Conference on Network Function Virtualization and Software Defined Networks , November 2015, San Francisco, USAWe are witnessing a considerable amount of research work related to data center and cloud infrastructures but evaluations are often limited to small-scale scenarios as very few researchers have access to a real infrastructure to confront their ideas to reality. In this demo we will reveal our experiment automation tool, DiG (Data centers in the Grid), which explicitly allocates physical resources in grids to emulate data center and cloud networks. DiG allows one to utilize grid infrastructures to evaluate research ideas pertaining to data centers and cloud environments at massive scale and with real traffic workload. We have automated the procedure of building target network topologies while respecting available physical resources in the grid against the demand of links and hosts in the experiment. We will present a showcase where DiG automatically builds a large data center topology composed of hundreds of servers executing various Hadoop intensive workloads

P4Bricks: Enabling multiprocessing using Linker-based network data plane architecture

Packet-level programming languages such as P4 usually require to describe all packet processing functionalities for a given programmable network device within a single program. However, this approach monopolizes the device by a single large network application program, which prevents possible addition of new functionalities by other independently written network applications. We propose P4Bricks, a system which aims to deploy and execute multiple independently developed and compiled P4 programs on the same reconfigurable hardware device. P4Bricks is based on a Linker component that merges the pro-grammable parsers/deparsers and restructures the logical pipeline of P4 programs by refactoring, decomposing and scheduling the pipelines' tables. It merges P4 programs according to packet processing semantics (parallel or sequential) specified by the network operator and runs the programs on the stages of the same hardware pipeline, thereby enabling multiprocessing. This paper presents the initial design of our system with an ongoing implementation and studies P4 language's fundamental constructs facilitating merging of independently written programs

Scalable Guaranteed-Bandwidth Multicast Service in Software Defined ISP networks

International audienceNew applications where anyone can broadcast video are becoming very popular on smartphones. With the advent of high definition video, ISP providers may take the opportunity to propose new high quality broadcast services to their clients. Because of its centralized control plane, Software Defined Networking (SDN) seems an ideal way to deploy such a service in a flexible and bandwidth-efficient way. But deploying large scale multicast services on SDN requires smart group membership management and a bandwidth reservation mechanism to support QoS guarantees that should neither waste bandwidth nor impact too severely best effort traffic. In this paper, we propose a Network Function Virtualization based solution for Software Defined ISP networks to implement scalable multicast group management. Then, we propose the Lazy Load balancing Multicast (L2BM) routing algorithm for sharing the network capacity in a friendly way between guaranteed-bandwidth multicast traffic and best-effort traffic. Our implementation of the framework made on Floodlight controllers and Open vSwitches is used to study the performance of L2BM

Terabit indoor laser-based wireless communications : LiFi 2.0 for 6G

This paper provides a summary of available technologies required for implementing indoor laser-based wireless networks capable of achieving aggregate data-rates of terabits per second as widely accepted as a sixth generation (6G) key performance indicator. The main focus of this paper is on the technologies supporting the near infrared region of the optical spectrum. The main challenges in the design of the transmitter and receiver systems and communication/networking schemes are identified and new insights are provided. This paper also covers the previous and recent standards as well as industrial applications for optical wireless communications (OWC) and LiFi

Towards network softwarization : a modular approach for network control delegation

Les opérateurs de réseau sont confrontés à de grands défis en termes de coût et de complexité pour intégrer les nouvelles technologies de communication (e.g., 4G, 5G, fibre optique) et pour répondre aux demandes croissantes des nouveaux services réseau adaptés aux nouveaux cas d’utilisation. La "softwarization" des opérations réseau à l'aide des paradigmes SDN (Software Defined Networking) et NFV (Network Function Virtualization) est en mesure de simplifier le contrôle et la gestion des réseaux et de fournir des services réseau de manière efficace. Les réseaux programmables SDN permettent de dissocier le plan de contrôle du plan de données et de centraliser le plan de contrôle pour simplifier la gestion du réseau et obtenir une vision globale. Cependant, ceci amène des problèmes de passage à l'échelle difficiles à résoudre. Par ailleurs, en dissociant la partie matérielle de la partie logicielle des routeurs, NFV permet d'implanter de manière flexible et à moindre coût toutes sortes de fonctions réseau. La contrepartie est une dégradation des performances due à l'implantation en logiciel des fonctions réseau qui sont déportées des routeurs. Pour aborder les problèmes de passage à l'échelle et de performance des paradigmes SDN/NFV, nous proposons dans la première partie de la thèse, une architecture modulaire de gestion et de contrôle du réseau, dans laquelle le contrôleur SDN délègue une partie de ses responsabilités à des fonctions réseau spécifiques qui sont instanciées à des emplacements stratégiques de l'infrastructure réseau. Nous avons choisi un exemple d'application de streaming vidéo en direct (comme Facebook Live ou Periscope) utilisant un service de multicast IP car il illustre bien les problèmes de passage à l'échelle des réseaux programmables. Notre solution exploite les avantages du paradigme NFV pour résoudre le problème de scalabilité du plan de contrôle centralisé SDN en délégant le traitement du trafic de contrôle propre au service multicast à des fonctions réseau spécifiques (appelées MNF) implantées en logiciel et exécutées dans un environnement NFV localisé à la périphérie du réseau. Notre approche fournit une gestion flexible des groupes multicast qui passe à l'échelle. De plus, elle permet de bénéficier de la vision globale du contrôle centralisé apportée par SDN pour déployer de nouvelles politiques d'ingénierie du trafic comme L2BM (Lazy Load Balance Multicast) dans les réseaux de fournisseurs d’accès à Internet (FAI) programmables. L'évaluation de cette approche est délicate à mettre en œuvre car la communauté de recherche ne dispose pas facilement d'infrastructure SDN à grande échelle réaliste. Pour évaluer notre solution, nous avons élaboré l'outil DiG qui permet d'exploiter l'énorme quantité de ressources disponibles dans une grille de calcul, pour émuler facilement de tels environnements. DiG prend en compte les contraintes physiques (mémoire, CPU, capacité des liens) pour fournir un environnement d'évaluation réaliste et paramétrable avec des conditions contrôlées. La solution que nous proposons délègue le contrôle et la gestion du réseau concernant le service de multicast aux fonctions spécifiques MNF exécutées dans un environnement NFV. Idéalement, pour davantage d'efficacité, toutes ces fonctions spécifiques devraient être implantées directement au sein des routeurs avec du hardware programmable mais cela nécessite que ces nouveaux routeurs puissent exécuter de manière indépendante plusieurs fonctions réseau à la fois. Le langage de programmation P4 est une technologie prometteuse pour programmer le traitement des paquets de données dans les routeurs programmables (hardware et logiciels).Network operators are facing great challenges in terms of cost and complexity in order to incorporate new communication technologies (e.g., 4G, 5G, fiber) and to keep up with increasing demands of new network services to address emerging use cases. Softwarizing the network operations using SoftwareDefined Networking (SDN) and Network Function Virtualization (NFV) paradigms can simplify control and management of networks and provide network services in a cost effective way. SDN decouples control and data traffic processing in the network and centralizes the control traffic processing to simplify the network management, but may face scalability issues due to the same reasons. NFV decouples hardware and software of network appliances for cost effective operations of network services, but faces performance degradation issues due to data traffic processing in software. In order to address scalability and performance issues in SDN/NFV, we propose in the first part of the thesis, a modular network control and management architecture, in which the SDN controller delegates part of its responsibilities to specific network functions instantiated in network devices at strategic locations in the infrastructure. We have chosen to focus on a modern application using an IP multicast service for live video streaming applications (e.g., Facebook Live or Periscope) that illustrates well the SDN scalability problems. Our solution exploits benefits of the NFV paradigm to address the scalability issue of centralized SDN control plane by offloading processing of multicast service specific control traffic to Multicast Network Functions (MNFs) implemented in software and executed in NFV environment at the edge of the network. Our approach provides smart, flexible and scalable group management and leverages centralized control of SDN for Lazy Load Balance Multicast (L2BM) traffic engineering policy in software defined ISP networks. Evaluation of this approach is tricky, as real world SDN testbeds are costly and not easily available for the research community. So, we designed a tool that leverages the huge amount of resources available in the grid, to easily emulate such scenarios. Our tool, called DiG, takes into account the physical resources (memory, CPU, link capacity) constraints to provide a realistic evaluation environment with controlled conditions. Our NFV-based approach requires multiple application specific functions (e.g., MNFs) to control and manage the network devices and process the related data traffic in an independent way. Ideally, these specific functions should be implemented directly on hardware programmable routers. In this case, new routers must be able to execute multiple independently developed programs. Packet-level programming language P4, one of the promising SDN-enabling technologies, allows applications to program their data traffic processing on P4 compatible network devices. In the second part of the thesis, we propose a novel approach to deploy and execute multiple independently developed and compiled applications programs on the same network device. This solution, called P4Bricks, allows multiple applications to control and manage their data traffic, independently. P4Bricks merges programmable blocks (parsers/deparsers and packet processing pipelines) of P4 programs according to processing semantics (parallel or sequential) provided at the time of deployment

(Q, R) inventory model with service level constraint and variable lead time in fuzzy-stochastic environment

In today's global marketplace, individual firms do not compete as independent entities rather as an integral part of a supply chain. Uncertainty is the main attribute in managing the supply chains. Accordingly, we develop a (Q, R) inventory model with service level constraint and variable lead-time in fuzzy-stochastic environment. In addition, the triangular fuzzy numbers counts upon lead-time are used to construct fuzzy-stochastic lead-time demand. Using credibility criterion, the expected shortages are calculated. Without loss of generality, we assume that all the observed values of the fuzzy random variable, representing the demand are triangular fuzzy numbers. Consequently, the value of total expected cost in the fuzzy sense is derived using the expected value criterion or credibility criterion. To determine an optimal policy, a numerical technique is presented and the results are analyzed using scan and zoom for constraint optimization. Finally, in order to demonstrate the accuracy and effectiveness of the proposed model, numerical example and sensitivity analysis are also included

Une approche modulaire avec délégation de contrôle pour les réseaux programmables

Network operators are facing great challenges in terms of cost and complexity in order to incorporate new communication technologies (e.g., 4G, 5G, fiber) and to keep up with increasing demands of new network services to address emerging use cases. Softwarizing the network operations using SoftwareDefined Networking (SDN) and Network Function Virtualization (NFV) paradigms can simplify control and management of networks and provide network services in a cost effective way. SDN decouples control and data traffic processing in the network and centralizes the control traffic processing to simplify the network management, but may face scalability issues due to the same reasons. NFV decouples hardware and software of network appliances for cost effective operations of network services, but faces performance degradation issues due to data traffic processing in software. In order to address scalability and performance issues in SDN/NFV, we propose in the first part of the thesis, a modular network control and management architecture, in which the SDN controller delegates part of its responsibilities to specific network functions instantiated in network devices at strategic locations in the infrastructure. We have chosen to focus on a modern application using an IP multicast service for live video streaming applications (e.g., Facebook Live or Periscope) that illustrates well the SDN scalability problems. Our solution exploits benefits of the NFV paradigm to address the scalability issue of centralized SDN control plane by offloading processing of multicast service specific control traffic to Multicast Network Functions (MNFs) implemented in software and executed in NFV environment at the edge of the network. Our approach provides smart, flexible and scalable group management and leverages centralized control of SDN for Lazy Load Balance Multicast (L2BM) traffic engineering policy in software defined ISP networks. Evaluation of this approach is tricky, as real world SDN testbeds are costly and not easily available for the research community. So, we designed a tool that leverages the huge amount of resources available in the grid, to easily emulate such scenarios. Our tool, called DiG, takes into account the physical resources (memory, CPU, link capacity) constraints to provide a realistic evaluation environment with controlled conditions. Our NFV-based approach requires multiple application specific functions (e.g., MNFs) to control and manage the network devices and process the related data traffic in an independent way. Ideally, these specific functions should be implemented directly on hardware programmable routers. In this case, new routers must be able to execute multiple independently developed programs. Packet-level programming language P4, one of the promising SDN-enabling technologies, allows applications to program their data traffic processing on P4 compatible network devices. In the second part of the thesis, we propose a novel approach to deploy and execute multiple independently developed and compiled applications programs on the same network device. This solution, called P4Bricks, allows multiple applications to control and manage their data traffic, independently. P4Bricks merges programmable blocks (parsers/deparsers and packet processing pipelines) of P4 programs according to processing semantics (parallel or sequential) provided at the time of deployment.Les opérateurs de réseau sont confrontés à de grands défis en termes de coût et de complexité pour intégrer les nouvelles technologies de communication (e.g., 4G, 5G, fibre optique) et pour répondre aux demandes croissantes des nouveaux services réseau adaptés aux nouveaux cas d’utilisation. La "softwarization" des opérations réseau à l'aide des paradigmes SDN (Software Defined Networking) et NFV (Network Function Virtualization) est en mesure de simplifier le contrôle et la gestion des réseaux et de fournir des services réseau de manière efficace. Les réseaux programmables SDN permettent de dissocier le plan de contrôle du plan de données et de centraliser le plan de contrôle pour simplifier la gestion du réseau et obtenir une vision globale. Cependant, ceci amène des problèmes de passage à l'échelle difficiles à résoudre. Par ailleurs, en dissociant la partie matérielle de la partie logicielle des routeurs, NFV permet d'implanter de manière flexible et à moindre coût toutes sortes de fonctions réseau. La contrepartie est une dégradation des performances due à l'implantation en logiciel des fonctions réseau qui sont déportées des routeurs. Pour aborder les problèmes de passage à l'échelle et de performance des paradigmes SDN/NFV, nous proposons dans la première partie de la thèse, une architecture modulaire de gestion et de contrôle du réseau, dans laquelle le contrôleur SDN délègue une partie de ses responsabilités à des fonctions réseau spécifiques qui sont instanciées à des emplacements stratégiques de l'infrastructure réseau. Nous avons choisi un exemple d'application de streaming vidéo en direct (comme Facebook Live ou Periscope) utilisant un service de multicast IP car il illustre bien les problèmes de passage à l'échelle des réseaux programmables. Notre solution exploite les avantages du paradigme NFV pour résoudre le problème de scalabilité du plan de contrôle centralisé SDN en délégant le traitement du trafic de contrôle propre au service multicast à des fonctions réseau spécifiques (appelées MNF) implantées en logiciel et exécutées dans un environnement NFV localisé à la périphérie du réseau. Notre approche fournit une gestion flexible des groupes multicast qui passe à l'échelle. De plus, elle permet de bénéficier de la vision globale du contrôle centralisé apportée par SDN pour déployer de nouvelles politiques d'ingénierie du trafic comme L2BM (Lazy Load Balance Multicast) dans les réseaux de fournisseurs d’accès à Internet (FAI) programmables. L'évaluation de cette approche est délicate à mettre en œuvre car la communauté de recherche ne dispose pas facilement d'infrastructure SDN à grande échelle réaliste. Pour évaluer notre solution, nous avons élaboré l'outil DiG qui permet d'exploiter l'énorme quantité de ressources disponibles dans une grille de calcul, pour émuler facilement de tels environnements. DiG prend en compte les contraintes physiques (mémoire, CPU, capacité des liens) pour fournir un environnement d'évaluation réaliste et paramétrable avec des conditions contrôlées. La solution que nous proposons délègue le contrôle et la gestion du réseau concernant le service de multicast aux fonctions spécifiques MNF exécutées dans un environnement NFV. Idéalement, pour davantage d'efficacité, toutes ces fonctions spécifiques devraient être implantées directement au sein des routeurs avec du hardware programmable mais cela nécessite que ces nouveaux routeurs puissent exécuter de manière indépendante plusieurs fonctions réseau à la fois. Le langage de programmation P4 est une technologie prometteuse pour programmer le traitement des paquets de données dans les routeurs programmables (hardware et logiciels)

Joint pricing and inventory decisions for perishable products with age-, stock-, and price-dependent demand rate

International audienceThis article presents a deterministic model for jointly optimising pricing and inventory control of a perishable product subject to both physical deterioration and freshness condition degradation. The demand for the product depends on its price, the current inventory level and the freshness condition. Our model allows for any positive amount of end-of-cycle inventory. Conditions for the existence and uniqueness of an optimal solution of the model are developed and an algorithm is suggested to find the optimal values of the price, the cycle length, the order quantity, and the end-of-cycle inventory. Then, numerical examples are given, and sensitivity analysis is performed. Our study contributes to satisfying the need for inventory models that consider simultaneous physical deterioration and freshness degradation of perishable products along with price-, age- and stock-dependent demand

Marking of temporal point and lower border of temporal triangle in planning hair transplantation for male-pattern baldness

Introduction: Temporal recession in male-pattern baldness is common. The method of marking of temporal point practiced worldwide, described by Walter P. Unger, does not help in marking temporal triangle border in Indian population. We have found aesthetically superior way of marking temporal point and easy method of construction of lower border of temporal triangle. Case Series: The new marking was applied over 126 young male patients from March 2014 to December 2017; they were regularly followed up and results were observed. Conclusion: With the new method of marking, we found that the lower border of temporal triangle can be easily constructed and temporal point can be more aesthetically placed in Indian population