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Gerhard Fettweis - One of the best experts on this subject based on the ideXlab platform.

  • high performance dynamic resource allocation for Guaranteed Service in network on chips
    IEEE Transactions on Emerging Topics in Computing, 2020
    Co-Authors: Yong Chen, Emil Matus, Sadia Moriam, Gerhard Fettweis
    Abstract:

    This paper proposes a dedicated connection allocation unit—the NoCManager—implementing the connection allocation functionality in circuit-switched network-on-chip (NoC) based on time-division-multiplexing (TDM). The NoCManager employs a novel trellis-search-algorithm (TESSA) that solves the allocation optimization problem by making use of dynamic programming approach. This enables to explore all possible paths between source-destination node pairs in order to determine the shortest available path. Three different trellis structures are proposed and analyzed for the purpose of different application scenarios. In contrast to previous TDM allocation approaches, the proposed method offers the following advantages: (1) hardware supported fast and high-throughput allocation mechanism; (2) improved success rate due to parallel multi-slot multi-path search mechanism; (3) selection of the contention-free shortest path with a Guaranteed low latency; (4) general mathematical formulation allowing a variety of optimization ideas. The proposed method is compared to the state of the art centralized and distributed techniques under uniformly distributed random traffic as well as real-application traffic. The experimental results demonstrate two orders of magnitude improvement in allocation speed and tens of times higher success rate against the centralized software solutions, and 5 to 10 percent higher success rate against the centralized hardware solution. Moreover, it achieves up to 8x higher allocation speed and up to 29 percent higher success rate against recently proposed distributed solution.

  • Guaranteed Service virtual channel allocation in nocs for run time task scheduling
    Design Automation and Test in Europe, 2011
    Co-Authors: Markus Winter, Gerhard Fettweis
    Abstract:

    Quality-of-Service becomes a vital requirement in MPSoCs with NoCs. In order to serve them NoCs provide guarantees for latency, jitter and bandwidth by virtual channels. But the allocation of these Guaranteed Service channels is still an important question. In this paper we present and evaluate different realizations of a central hardware unit which allocates at run-time Guaranteed Service virtual channels providing QoS in packet-switched NoCs. We evaluate their performance in terms of allocation success, compare it to distributed channel setup techniques for different NoC sizes and traffic scenarios and analyze the required hardware area consumption. We find centralized channel allocation to be very suitable for our run-time task scheduling programming model.

  • DATE - Guaranteed Service virtual channel allocation in NoCs for run-time task scheduling
    2011 Design Automation & Test in Europe, 2011
    Co-Authors: Markus Winter, Gerhard Fettweis
    Abstract:

    Quality-of-Service becomes a vital requirement in MPSoCs with NoCs. In order to serve them NoCs provide guarantees for latency, jitter and bandwidth by virtual channels. But the allocation of these Guaranteed Service channels is still an important question. In this paper we present and evaluate different realizations of a central hardware unit which allocates at run-time Guaranteed Service virtual channels providing QoS in packet-switched NoCs. We evaluate their performance in terms of allocation success, compare it to distributed channel setup techniques for different NoC sizes and traffic scenarios and analyze the required hardware area consumption. We find centralized channel allocation to be very suitable for our run-time task scheduling programming model.

Sean P Willems - One of the best experts on this subject based on the ideXlab platform.

  • analytical insights into two stage serial line supply chain safety stock
    International Journal of Production Economics, 2016
    Co-Authors: Sean P Willems
    Abstract:

    Effective inventory management is one of the most significant challenges facing today׳s global supply chains. Businesses are observing significant profitability gain by optimizing their inventory. This paper optimizes safety stock inventory in a two-stage serial line supply chain, inspired by real-life Cisco supply chains, under Guaranteed-Service safety stock model assumptions. We analytically show that the optimal safety stock levels depend on the cost and leadtime parameters of the supply chain. Intuitively, it is only worthwhile to hold safety stock inventory at the upstream stage when cost at the upstream stage is relatively low or its leadtime is relatively long. We also show that total supply chain safety stock cost can be reduced when cost allocated at the upstream stage is reduced or leadtime at the upstream stage is increased.

  • incorporating stochastic lead times into the Guaranteed Service model of safety stock optimization
    Interfaces, 2013
    Co-Authors: Salal Humair, John D Ruark, Brian Tomlin, Sean P Willems
    Abstract:

    Effective end-to-end supply chain management and network inventory optimization must account for Service levels, demand volatility, lead times, and lead-time variability. Most inventory models incorporate demand variability, but far fewer rigorously account for lead-time variability, particularly in multiechelon supply chain networks. Our research extends the Guaranteed Service model of safety stock placement to allow random lead times. The main methodological contribution is the creation of closed-form equations for the expected safety stock in the system; this includes a derivation for the early-arrival stock in the system. The main applied contributions are the demonstration of real stochastic lead times in practice and a discussion of how our approach outperforms more traditional heuristics that either ignore lead-time variability or consider the maximum lead time at each stage.

  • a periodic review modeling approach for Guaranteed Service supply chains
    Interfaces, 2007
    Co-Authors: John M Bossert, Sean P Willems
    Abstract:

    We extend the Guaranteed Service, supply chain modeling framework to allow for an arbitrary, integer review period or ordering frequency at each stage. We define a notation for the cyclic inventory dynamics that review periods introduce and generalize inventory-balance equations to accommodate three different periodic-review operating policies---constant base stock, constant safety stock, and adaptive base stock. As a form of validation, we apply the model to the Celanese acetic acid supply chain and show that inventory metrics of the new model differ by more than 30 percent from those derived through the simpler modeling approach of aggregating a review period into lead time.

  • supply chain design safety stock placement and supply chain configuration
    Handbooks in Operations Research and Management Science, 2003
    Co-Authors: Stephen C Graves, Sean P Willems
    Abstract:

    Publisher Summary This chapter discusses two approaches to safety stock placement, which are termed as “stochastic-Service model” and the “Guaranteed-Service model.” In the stochastic-Service model, each stage in the supply chain maintains a safety stock sufficient to meet its Service level target. In this setting, a stage that has one or more upstream-adjacent supply stages has to characterize its replenishment time taking into account the likelihood that these suppliers will meet a replenishment request from stock. In the Guaranteed-Service model, each stage provides a Guaranteed Service to its customer stages. In this setting, a supply stage sets a Service time to its downstream customer and then holds sufficient inventory so that it can always satisfy the Service-time commitment. A key assumption in this model is to assume that demand is bounded for the purpose of making the Service-time guarantee. The chapter also discusses how the supply chain can be optimally configured. The notion of options are introduced for each stage in the supply chain, where the options differ in terms of lead-time and cost.

Markus Winter - One of the best experts on this subject based on the ideXlab platform.

  • Guaranteed Service virtual channel allocation in nocs for run time task scheduling
    Design Automation and Test in Europe, 2011
    Co-Authors: Markus Winter, Gerhard Fettweis
    Abstract:

    Quality-of-Service becomes a vital requirement in MPSoCs with NoCs. In order to serve them NoCs provide guarantees for latency, jitter and bandwidth by virtual channels. But the allocation of these Guaranteed Service channels is still an important question. In this paper we present and evaluate different realizations of a central hardware unit which allocates at run-time Guaranteed Service virtual channels providing QoS in packet-switched NoCs. We evaluate their performance in terms of allocation success, compare it to distributed channel setup techniques for different NoC sizes and traffic scenarios and analyze the required hardware area consumption. We find centralized channel allocation to be very suitable for our run-time task scheduling programming model.

  • DATE - Guaranteed Service virtual channel allocation in NoCs for run-time task scheduling
    2011 Design Automation & Test in Europe, 2011
    Co-Authors: Markus Winter, Gerhard Fettweis
    Abstract:

    Quality-of-Service becomes a vital requirement in MPSoCs with NoCs. In order to serve them NoCs provide guarantees for latency, jitter and bandwidth by virtual channels. But the allocation of these Guaranteed Service channels is still an important question. In this paper we present and evaluate different realizations of a central hardware unit which allocates at run-time Guaranteed Service virtual channels providing QoS in packet-switched NoCs. We evaluate their performance in terms of allocation success, compare it to distributed channel setup techniques for different NoC sizes and traffic scenarios and analyze the required hardware area consumption. We find centralized channel allocation to be very suitable for our run-time task scheduling programming model.

Yves Dallery - One of the best experts on this subject based on the ideXlab platform.

  • a comprehensive survey of Guaranteed Service models for multi echelon inventory optimization
    International Journal of Production Economics, 2016
    Co-Authors: Ayse Sena Eruguz, Zied Jemai, Evren Sahin, Yves Dallery
    Abstract:

    Many real-world supply chains are multi-echelon systems consisting of several stages of procurement, manufacturing, and transportation. In such systems, it is not obvious how to allocate safety stocks to meet the target Service levels at the lowest cost. The Guaranteed-Service model (GSM) is among the existing approaches that allow this problem to be addressed. Although the Guaranteed-Service model (GSM) was introduced more than 50 years ago, the last decade has witnessed a growing interest. The model extensions and the solution methods developed have expanded the applicability of the GSM. In this paper, we conduct a comprehensive review of the GSM literature. We classify the literature along three axes: (1) extensions of the original GSM through the relaxation of certain modeling assumptions, (2) solution methods developed for different supply chain structures, and (3) industrial applications and the results obtained on real-world problems. Finally, we discuss unsolved issues and suggest future research directions.

  • Cycle-Service-Level in Guaranteed-Service supply chains
    2013 5th International Conference on Modeling Simulation and Applied Optimization (ICMSAO), 2013
    Co-Authors: Ayse Sena Eruguz, Zied Jemai, Evren Sahin, Yves Dallery
    Abstract:

    The Guaranteed-Service Model (GSM) aims at determining the optimal placement and amount of safety stocks in a Guaranteed-Service supply chain. In the GSM, safety stocks are used to protect against demand variability up to specified demand bounds. The model does not address what happens when demand exceeds these bounds while in practice, companies might take extraordinary measures to handle the excess demand. For Guaranteed-Service supply chains, assessing the Service level that results from carrying safety stocks is crucial to estimate the real frequency of extraordinary measures to be deployed. In the GSM literature, demand bounds are usually defined in terms of Cycle-Service-Level (CSL). Simulation studies we carried for realworld supply chains show that the effectively observed CSL at final customer stages may be less than the one used to define the demand bounds and the absolute gap may be up to 4.76%.

  • Applying the Guaranteed-Service model to a decentralized supply chain: Impact on the Cycle-Service-Level
    Proceedings of 2013 International Conference on Industrial Engineering and Systems Management (IESM), 2013
    Co-Authors: Ayse Sena Eruguz, Zied Jemai, Evren Sahin, Yves Dallery
    Abstract:

    In a multi-echelon inventory system, the Guaranteed-Service Model (GSM) aims at determining the optimal placement and amount of safety stocks that ensures a target Service level at the lowest cost. This model assumes that demand is bounded at each stage of the considered supply chain where demand bounds are usually obtained on the basis of a target Cycle-Service-Level (CSL). Recent works show that the GSM can also be applied to decentralized supply chains, i.e. when different parts of the supply chain are controlled by different actors. However, the choice of demand bounds at different parts of the supply chain may affect the final customer CSL. This fact is usually ignored in the existing literature. In this paper, we first illustrate how the upstream demand bounds affect the downstream customer CSL. Besides, we propose two approaches that ensure to reach the target CSL in decentralized supply chains.

  • a review of the Guaranteed Service model for multi echelon inventory systems
    IFAC Proceedings Volumes, 2012
    Co-Authors: Ayse Sena Eruguz, Zied Jemai, Evren Sahin, Yves Dallery
    Abstract:

    Guaranteed-Service Model (GSM) approach for the safety stock placement problem aims at finding the optimal placement of safety stocks in a multi-echelon inventory system under bounded demand and Guaranteed Service times. Although this model has been present for more than fifty years, the last decade witnessed a growing interest. Recent works include new versions of the problem with relaxed assumptions and efficient solution methods for different supply chain network topologies. The purpose of this paper is to review and summarize the literature on the GSM and to suggest future research directions.

Ying Li - One of the best experts on this subject based on the ideXlab platform.

  • towards optimal lifetime in wireless sensor networks for qos Guaranteed Service selection
    Pacific Rim International Conference on Artificial Intelligence, 2014
    Co-Authors: Endong Tong, Lan Chen, Ying Li
    Abstract:

    Due to the efficiency and practicability, workflow has been successfully used in Service-oriented Wireless Sensor Networks (WSNs). In general, Quality of Service (QoS) can be utilized to select the optimal Service. However, WSNs are resource constrained, especially the energy. If we ignore the issue of limited energy, Services with best QoS will consume their energy heavily and disabled earlier, which will shorten the network lifetime. Hence, in this paper, we will propose an energy efficient and QoS Guaranteed Service selection approach in WSNs. Through decomposing the global QoS constraints into a set of local QoS constraints, we can get a group of QoS Guaranteed candidate Services. Furthermore, considering of the Service profile (i.e. running status, energy and QoS), we adopt fuzzy logic technique to rank the candidate Services and then select the optimal one. Experimental evaluations demonstrate the capability of the proposed approach.

  • PRICAI - Towards Optimal Lifetime in Wireless Sensor Networks for QoS Guaranteed Service Selection
    Lecture Notes in Computer Science, 2014
    Co-Authors: Endong Tong, Lan Chen, Ying Li
    Abstract:

    Due to the efficiency and practicability, workflow has been successfully used in Service-oriented Wireless Sensor Networks (WSNs). In general, Quality of Service (QoS) can be utilized to select the optimal Service. However, WSNs are resource constrained, especially the energy. If we ignore the issue of limited energy, Services with best QoS will consume their energy heavily and disabled earlier, which will shorten the network lifetime. Hence, in this paper, we will propose an energy efficient and QoS Guaranteed Service selection approach in WSNs. Through decomposing the global QoS constraints into a set of local QoS constraints, we can get a group of QoS Guaranteed candidate Services. Furthermore, considering of the Service profile (i.e. running status, energy and QoS), we adopt fuzzy logic technique to rank the candidate Services and then select the optimal one. Experimental evaluations demonstrate the capability of the proposed approach.