System Margin Research Articles

On Justice, Pedagogy, and Decolonial(Izing) Praxis

AbstractThis paper goes beyond — transcends — “pedagogy as justice,” recognizing that justice, particularly in these present times, may not be enough. Its wager is with pedagogies of and for life; pedagogies that plant and cultivate, that push and enable other modes of living, despite the capitalist‐modern‐colonial‐racist system, beyond the system, and in the system's margins, borders, fissures, and cracks. These pedagogies, as Catherine Walsh argues here, are necessarily tied to and constitutive of decolonial(izing) praxis, a praxis that, while not negating justice, takes us beyond it. The argument here is for the pedagogical‐praxistical work being done now, and yet to be done; the actional thought, thoughtful action, and ongoing creation and construction of an otherwise for existence, for dignity, and for life in these times of multiple entwined pandemic‐viruses, including capitalist greed, systemic racism, heteropatriarchy, and existential‐territorial dispossession in which COVID is/was one more thread of the entwine.

Surrogate‐splits ensembles for real‐time voltage stability assessment in the presence of missing synchrophasor measurements

This paper proposes a new machine learning approach in the presence of missing measurements using surrogate-splits ensembles for real-time voltage stability assessment comprising of the classification of the operating state of the power system, and the prediction of the power system's margin to voltage collapse. The proposed approach applied the Boosting and Bagging machine learning methods in the design of the ensemble models required for the classification and regression tasks, respectively, based on the feature attributes obtained from synchrophasor measurements. The performance of the trained classifiers and regressors was evaluated for the case of missing phasor measurement unit (PMU) measurements. Robust classifier and regressor models immune to missing PMU measurements were afterwards developed using the surrogate-splits technique. The validity of the proposed approach was tested using the New England 39-bus test system. The experimental results obtained validate the effectiveness of the proposed method for various operating scenarios and contingencies even in the presence of missing PMU measurements.

Colorless WDM-PON using single side band carrier suppressed signals mitigating carrier rayleigh backscattering

A new scheme is offered for minimizing carrier Rayleigh backscattering (CRB) in single feeder fiber based wavelength division multiplexed passive optical network (WDM-PON). The proposed scheme is based on single side band carrier suppressed (SSB-CS)signal, both at network and receiver sides, used for the first time at optical line terminal (OLT) and optical network unit (ONU)sides. We use dual-drive Mach-zehnder modulator (DD-MZM)for generating SSB-CS signals, which decreased the expense per bit in full transmission. SSB-S mitigated CRB, both at OLT and ONU sides, because of having no chance of reflections from the carrier. Since no extra dedicated RF or laser source is used at ONU side, we thus achieve cost effective colorless WDM-PON system. Suppressed signals from four channels, each of 10 Gbps, are multiplexed before injecting into the fiber span of 25 km at OLT. At ONU side, half of the down-link power is used for re-modulating the data signal. The simulation results show an error free transmission. Moreover, the detailed power budget calculations show that the proposed scheme can be sought out for splitting ratio up to 128. Hence it offers enough system's margin for unseen losses.

Extended synchrophasor-based online voltage stability assessment using synchronous generator-derived indices

Summary This paper proposes and investigates the online application of generator-derived real-time voltage stability assessment indices in large interconnected power systems. The indices are based on synchrophasor measurements from synchronous generators and are used in the prediction of the system's margin to voltage collapse in real-time. Comparative analyses are carried out between the newly proposed indices, an existing effective generator reactive power reserve index, and two line-based indices. Results obtained from testing the proposed indices on the New England 39-bus test system show that the proposed indices are simple to implement, more responsive to system dynamics and provide a more accurate estimation of the system's margin to voltage collapse compared with the existing indices. Furthermore, the suitability of the proposed indices for small disturbance voltage instability and large disturbance voltage instability conditions were demonstrated. In addition, the proposed indices are subsequently deployed on a programmable logic controller for real-time closed-loop testing with the real-time digital simulator. Copyright © 2016 John Wiley & Sons, Ltd.

Cost effective scheme for OLT in next generation passive optical access network based on noise free optical multi carrier

We propose a cost-effective multi-carrier generation technique which minimizes the passive optical access network (PON) costs. In this study replacement of laser array with multi-carrier source at optical line terminal (OLT) side in PON is addressed. With 25-GHz frequency spacing, the generated optical multi-carriers exhibit good tone to noise ratio (TNR) i. e. above 20dB, and least amplitude difference i. e. 1.5dB. At the OLT, multi-carriers signal based multiplexed differential phase shift keying (DPSK) data from all the channels each having 10Gbps for downlink is transmitted through 25km single mode fiber. While the transmitted information is retrieved at optical network unit (ONU), part of the downlink signal is re-modulated using intensity modulated (IM) on-off keying(OOK) for upstream transmission at 10-Gbps. Simulation results are in good agreement with the theoretical analysis, showing error free transmission in downlink and uplink with 10Gbps symmetric data rate at each channel. The received power, both for uplink and downlink transmission, is adequate for all channels at BER of 10−9 with minimum power penalties. Power budget is calculated for different splitting ratios showing excellent system margins for any unseen losses. The proposed setup provides a cost-effective way minimizing transmission losses, and providing greater system's margin in PON architecture.

Proposed Planet Nine Elicits Cheers, Yawns, Hunt for Proof

Evidence of a large, unseen planet at the solar system's margins prompted a flurry of scientific paper downloads, as well as oodles of skepticism. There's no sighting yet of the purported body.

Clearing networks

In several financial markets, counterparty risk is reallocated away from traders via ‘novation’, a step of the clearing process. By novation, a third party steps into a bilateral contract, guaranteeing performance of both legs of the trade. Central counterparties (CCPs) are entities whose special purpose is novating trades, relieving market participants from counterparty risk. However, in most cases, the CCP is not the sole novator: the CCP novates contracts between its clearing members, which in turn novate trades for other (typically smaller) participants and so on.This paper develops an abstract model of such hierarchical clearing networks. Novation is modelled here as a function which transforms (trading) exposures into (cleared) exposures. By using Monte Carlo simulations, we study how such function is affected by the clearing network's topology, drawing conclusions on the risks faced by the CCP, and on the system's margin requirements.

Twenty Years After the Cold War: A Strategic Survey

This 2011 article attempts to put the post-Cold War period (1990-2010) into perspective and argues for its having been defined by six key trends: 1. The receding of great power conflict 2. A shift from interstate to intrastate warfare, with both forms of conflict concentrated on the system's margins 3. The continued deepening of neoliberal globalization, and its associated problems. 4. The shift in world output and trade balances toward East Asia. 5. The continued salience of resource politics, and 6. The underwhelming record of international cooperation in every area besides free trade. The article argues that American policy should emphasize the redress of the country's problems with regard to its balance of payments, manufacturing base, infrastructure and energy dependence, while abroad concentrating on cooperation with other major states in the redress of the economic and ecological vulnerabilities of the international system, failing to do which may threaten a resurgence of the great power conflict traditionally at the center of international relations.