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Abstract-How much margin do we have to add to the delay lines of a bundled-data circuit? This paper is an attempt to give a methodical answer to this question, taking into account all sources of variability and the existing EDA machinery for timing analysis and sign-off. The paper is based on the study of the margins of a ring oscillator that substitutes a PLL as clock generator. A timing model is proposed that shows that a 12% margin for delay lines can be sufficient to cover variability in a 65nm technology. In a typical scenario, performance and energy improvements between 15% and 35% can be obtained by using a ring oscillator instead of a PLL. The paper concludes that a synchronous circuit with a ring oscillator clock shows similar benefits in performance and energy as those of bundled-data asynchronous circuits.

Abstract-The growing variability in nanoelectronic devices, due to uncertainties from the manufacturing process and environmental conditions (power supply, temperature, aging), requires increasing design guardbands, forcing circuits to work with conservative clock frequencies. Various schemes for clock generation based on ring oscillators and adaptive clocks have been proposed with the goal to mitigate the power and performance losses attributable to variability. However, there has been no systematic analysis to quantify the benefits of such schemes and no signoff method has been proposed for timing correctness. This paper presents and analyzes a Reactive Clocking scheme with Variability-Tracking Jitter (RClk) that uses variability as an opportunity to reduce power by continuously adjusting the clock frequency to the varying environmental conditions, and thus, reduces guardband margins significantly. Power can be reduced between 20% and 40% at iso-performance and performance can be boosted by similar amounts at iso-power. Additionally, energy savings can be translated to substantial advantages in terms of reliability and thermal management. More importantly, the technology can be adopted with minimal modifications to conventional EDA flows.

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This article presents a comparative study of the performance of classification techniques used for fault diagnosis in industrial processes. The techniques studied ranging from classifiers based on Bayes theory as Maximum a Posteriori Probability (MAP) and Nearest Neighbor (kNN) classifiers, through minimizing an objective function such as Artificial Neural Networks (ANN) and Support Machines Vector (SVM) and ending with the parameter estimation technique Partial Least Squares (PLS). Comparison of these techniques is based on the capacity of classification of the historical data and the generalization of new observations. Also, a discussion about the robustness of the classifiers against the dimensionality reduction process is presented. The study was conducted using the data from the testing process "Tennessee Eastman Process" (TEP).

This paper presents and compares different TE information dissemination strategies between Path Computation Elements (PCEs) in multi-domain optical networks. In such network context, recent studies have found that path computation only with local domain visibility yields poor network performance. Accordingly, certain visibility between domains seems necessary. Aiming to fit the confidentiality requirements of the composing domains while improving the final network blocking probability, novel link aggregation techniques have been proposed, which summarize the state of network domains resources efficiently. This aggregated link information is afterwards disseminated to all the remainder domains in the network. To this end, we introduce different update triggering policies to make a good trade-off between routing information scalability and inaccuracy. The performance of all contributions has been supported by illustrative simulation results. Keywords: Multi-domain, path computation element, topology abstraction. INTRODUCTIONIn the last decade, research efforts related to optical transport network infrastructures, have been mainly focused on single-domain scenarios, where scalability and confidentiality do not represent an issue. However, the future optical networks will include several domains, each controlled by a different service provider/network operator. From the routing perspective, a domain is a collection of network elements within a common address management or path computational responsibility, namely, an Interior Gateway Protocol (IGP) area or an Autonomous System (AS) [1]. In such scenario, the computation of end-to-end paths poses new challenges and traffic engineering solutions addressing the constraints imposed by scalability, domain information confidentiality, heterogeneous transmission technologies and physical layer impairments, must be provided. Due to the limited availability of effective solutions, TE is practically unavailable in multi-domain optical networks. The topological information exchange between domains is normally reduced to the minimum, only spanning the shared links and border nodes information. The lack of topological information related to neighbouring domains hinders the routing entities' capacity to compute inter-domain end-to-end paths efficiently. To address this problem, the Internet Engineering Task Force (IETF) and the Optical Internetworking Forum (OIF) standardization bodies have proposed both architectural and protocol specifications to facilitate the interoperability amid different network domains, technologies and vendor equipments.Specifically, referring to IETF and Path Computation Element (PCE)-based solutions, path computation strategies such as per-domain path computation [3] and Backward Recursive PCE-based Computation (BRPC) [4] have been introduced. In the former, for end-to-end path computation, only border nodes information is used and the PCE of each traversed domain computes the local section of the path (i.e., intra-domain connection). In the la...

SPICE piecewise linear resistor (PWLR) and piecewise current‐controlled (PWCC) current source models are applied to represent conventional loads of PV systems, namely, a washing machine, a refrigerator, lights and a d.c.–a.c. converter. The parameter extraction for these models has been performed by experimental measurements. A complete system of 440 Wp has been simulated and the results compared to experimental measurements. Future application advanced dispatching strategies and intelligent load management are indicated as possible uses of these models. Copyright © 2000 John Wiley & Sons, Ltd.

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