130 research outputs found

    Temperature Overloads in Power Grids Under Uncertainty: a Large Deviations Approach

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    The advent of renewable energy has huge implications for the design and control of power grids. Due to increasing supply-side uncertainty, traditional reliability constraints such as strict bounds on current, voltage and temperature in a transmission line have to be replaced by computationally demanding chance constraints. In this paper we use large deviations techniques to study the probability of current and temperature overloads in power grids with stochastic power injections, and develop corresponding safe capacity regions. In particular, we characterize the set of admissible power injections such that the probability of overloading of any line over a given time interval stays below a fixed target. We show how enforcing (stochastic) constraints on temperature, rather than on current, results in a less conservative approach and can thus lead to capacity gains.Comment: 12 pages (10 pages + 2 pages appendix), 2 figures. Revised version with extended numerical sectio

    Congestion Control for Network-Aware Telehaptic Communication

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    Telehaptic applications involve delay-sensitive multimedia communication between remote locations with distinct Quality of Service (QoS) requirements for different media components. These QoS constraints pose a variety of challenges, especially when the communication occurs over a shared network, with unknown and time-varying cross-traffic. In this work, we propose a transport layer congestion control protocol for telehaptic applications operating over shared networks, termed as dynamic packetization module (DPM). DPM is a lossless, network-aware protocol which tunes the telehaptic packetization rate based on the level of congestion in the network. To monitor the network congestion, we devise a novel network feedback module, which communicates the end-to-end delays encountered by the telehaptic packets to the respective transmitters with negligible overhead. Via extensive simulations, we show that DPM meets the QoS requirements of telehaptic applications over a wide range of network cross-traffic conditions. We also report qualitative results of a real-time telepottery experiment with several human subjects, which reveal that DPM preserves the quality of telehaptic activity even under heavily congested network scenarios. Finally, we compare the performance of DPM with several previously proposed telehaptic communication protocols and demonstrate that DPM outperforms these protocols.Comment: 25 pages, 19 figure

    Evaluation of canola meal derived from Brassica juncea and Brassica napus as an energy source for cattle

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    Two trials were carried out to evaluate the effect of inclusion level of canola meal derived from Brassica (B.) napus and B. juncea on cattle performance and nutrient utilization. Trial 1 consisted of backgrounding (54 d) and finishing (153 d) phases. The control diet for the backgounding (BK) phase consisted of 39% barley silage, 30.4% barley grain, 22.8% brome grass hay and 7.8% supplement (DM). Treatments consisted of B. napus or B. juncea at 15 or 30% (DM) inclusion, replacing barley grain. The finishing control diet consisted of 88.3% barley grain, 4.4% barley silage and 7.3% supplement (DM). Treatments consisted of B. napus or B. juncea at 10 or 20% (DM) inclusion, replacing barley grain. During BK, dry matter intake (DMI), average daily gain (ADG), gain: feed (G:F) increased linearly (P < 0.01) as the level of inclusion of B. juncea meal increased. Cattle fed B. napus meal showed a quadratic response (P = 0.05) in DMI and linear increase (P = 0.02) in ADG with increasing inclusion. During finishing, DMI increased linearly (P = 0.05) for cattle fed B. juncea meal while a quadratic response (P = 0.02) was seen with B. napus meal. Feed efficiency and NEg content of the diet (P ≤ 0.02) decreased linearly with increasing inclusion of both meals. Trial 2 evaluated dietary rumen fermentation and total tract digestibility characteristics in a 5 x 5 Latin Square Design. Diets were similar to finishing phase of Trial 1. There was no effect of treatment on rumen pH, however a linear increase in acetate (P ≤ 0.01), ammonia (P < 0.01) and decrease (P < 0.01) in propionate was seen with both meal types. Crude protein and acid detergent fiber digestibility increased (P = 0.03) linearly with increasing inclusion of B. juncea meal. The results indicate that canola meal derived from B. napus and B. juncea is not suitable as a supplemental energy source replacing for barley grain in finishing diets but canola meal from B. juncea can be fed at levels up to 30% of the DM in backgrounding diets if priced appropriately
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