Evaluation of the impact of heat-wave on distribution system resilience

This paper addresses the impact of heat waves on a real urban distribution system. A data-driven methodology is proposed to simulate the portion of faults that can be associated to normal conditions (and hence to reliability) and the portion correlated to the heat wave occurrence. Based on real data collected in the years 2012-2017, the fault rates associated to reliability and resilience have been calculated and then used to feed a Monte Carlo simulation aiming to manage the uncertainty in the fault occurrence. Finally, based on the Italian legislation, the avoided costs deriving by the substitution of the faulted portion of the system have been calculated. The results show the different nature of reliability and resilience in terms of empirical cumulative curve, suggesting the necessity of using a stochastic-based methodology within regulatory frameworks, especially in case of output-based regulation

Thruster Plume Plasma Diagnostics: A Ground Chamber Experiment for a 2-Kilowatt Arcjet

Although detailed near field (0 to 3 cm) information regarding the exhaust plume of a two kilowatt arc jet is available (refs. 1 to 6), there is virtually little or no information (outside of theoretical extrapolations) available concerning the far field (2.6 to 6.1 m). Furthermore real information about the plasma at distances between (3 to 6 m) is of critical importance to high technology satellite companies in understanding the effect of arc jet plume exhausts on space based power systems. It is therefore of utmost importance that one understands the exact nature of the interaction between the arc jet plume, the spacecraft power system and the surrounding electrical plasma environment. A good first step in understanding the nature of the interactions lies in making the needed plume parameter measurements in the far field. All diagnostic measurements are performed inside a large vacuum system (12 m diameter by 18 m high) with a full scale arc jet and solar array panel in the required flight configuration geometry. Thus, necessary information regarding the plume plasma parameters in the far field is obtained. Measurements of the floating potential, the plasma potential, the electron temperature, number density, density distribution, debye length, and plasma frequency are obtained at various locations about the array (at vertical distances from the arc jet nozzle: 2.6, 2.7, 2.8, 3.2, 3.6, 4.0, 4.9, 5.0, 5.4, 5.75, and 6.14 m). Plasma diagnostic parameters are measured for both the floating and grounded configurations of the arc jet anode and array. Spectroscopic optical measurements are then acquired in close proximity to the nozzle, and contamination measurements are made in the vicinity of the array utilizing a mass spectrometer and two Quartz Crystal Microbalances (QCM's)

Arcing in LEO: Does the Whole Array Discharge?

The conventional wisdom about solar array arcing in LEO is that only the parts of the solar array that are swept over by the arc-generated plasma front are discharged in the initial arc. This limits the amount of energy that can be discharged. Recent work done at the NASA Glenn Research Center has shown that this idea is mistaken. In fact, the capacitance of the entire solar array may be discharged, which for large arrays leads to very large and possibly debilitating arcs, even if no sustained arc occurs. We present the laboratory work that conclusively demonstrates this fact by using a grounded plate that prevents the arc-plasma front from reaching certain array strings. Finally, we discuss the dependence of arc strength and arc pulse width on the capacitance that is discharged, and provide a physical mechanism for discharge of the entire array, even when parts of the array are not accessible to the arc-plasma front. Mitigation techniques are also presented

NASA GRC and MSFC Space-Plasma Arc Testing Procedures

Tests of arcing and current collection in simulated space plasma conditions have been performed at the NASA Glenn Research Center (GRC) in Cleveland, Ohio, for over 30 years and at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, for almost as long. During this period, proper test conditions for accurate and meaningful space simulation have been worked out, comparisons with actual space performance in spaceflight tests and with real operational satellites have been made, and NASA has achieved our own internal standards for test protocols. It is the purpose of this paper to communicate the test conditions, test procedures, and types of analysis used at NASA GRC and MSFC to the space environmental testing community at large, to help with international space-plasma arcing-testing standardization. Discussed herein are neutral gas conditions, plasma densities and uniformity, vacuum chamber sizes, sample sizes and Debye lengths, biasing samples versus self-generated voltages, floating samples versus grounded samples, test electrical conditions, arc detection, preventing sustained discharges during testing, real samples versus idealized samples, validity of LEO tests for GEO samples, extracting arc threshold information from arc rate versus voltage tests, snapover, current collection, and glows at positive sample bias, Kapton pyrolysis, thresholds for trigger arcs, sustained arcs, dielectric breakdown and Paschen discharge, tether arcing and testing in very dense plasmas (i.e. thruster plumes), arc mitigation strategies, charging mitigation strategies, models, and analysis of test results. Finally, the necessity of testing will be emphasized, not to the exclusion of modeling, but as part of a complete strategy for determining when and if arcs will occur, and preventing them from occurring in space

NASA GRC and MSFC Space-Plasma Arc Testing Procedures

Tests of arcing and current collection in simulated space plasma conditions have been performed at the NASA Glenn Research Center (GRC) in Cleveland, Ohio, for over 30 years and at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, for almost as long. During this period, proper test conditions for accurate and meaningful space simulation have been worked out, comparisons with actual space performance in spaceflight tests and with real operational satellites have been made, and NASA has achieved our own internal standards for test protocols. It is the purpose of this paper to communicate the test conditions, test procedures, and types of analysis used at NASA GRC and MSFC to the space environmental testing community at large, to help with international space-plasma arcing-testing standardization. To be discussed are: 1.Neutral pressures, neutral gases, and vacuum chamber sizes. 2. Electron and ion densities, plasma uniformity, sample sizes, and Debuy lengths. 3. Biasing samples versus self-generated voltages. Floating samples versus grounded. 4. Power supplies and current limits. Isolation of samples from power supplies during arcs. 5. Arc circuits. Capacitance during biased arc-threshold tests. Capacitance during sustained arcing and damage tests. Arc detection. Prevention sustained discharges during testing. 6. Real array or structure samples versus idealized samples. 7. Validity of LEO tests for GEO samples. 8. Extracting arc threshold information from arc rate versus voltage tests. 9. Snapover and current collection at positive sample bias. Glows at positive bias. Kapon (R) pyrolisis. 10. Trigger arc thresholds. Sustained arc thresholds. Paschen discharge during sustained arcing. 11. Testing for Paschen discharge threshold. Testing for dielectric breakdown thresholds. Testing for tether arcing. 12. Testing in very dense plasmas (ie thruster plumes). 13. Arc mitigation strategies. Charging mitigation strategies. Models. 14. Analysis of test results. Finally, the necessity of testing will be emphasized, not to the exclusion of modeling, but as part of a complete strategy for determining when and if arcs will occur, and preventing them from occurring in space

Assessing the potential of Suez Canal shipping traffic as an invasion pathway for non-indigenous species in Central Mediterranean harbours

The shipping traffic visiting seven Central Mediterranean ports within Sicily and Malta over a period of one year (2013) and the ballast water volumes it transported was quantified and classified according to port of origin in order to assess the influence of traffic navigating through the Suez Canal on the marine biota of the same geographical area. Scraping and benthic sediment collection exercises were also conducted within the same ports and a list of non -indigenous species is reported.peer-reviewe

La nonna di Cappuccetto rosso era una strega! Dialogo sulla morfogenesi della fiaba

Questo dialogo nasce da una rilettura della polemica tra L\ue9vi-Strauss e Vladimir Propp. La concezione dello studioso del folklore russo appare oggi di grande interesse date le sue radici nella idea goethiana di morfogenesi. Negli ultimi vent\u2019anni e a partire dal lavoro di Ren\ue9 Thom, questa concezione si \ue8 rivelata molto feconda in semiotica, e ha portato a confronti con il cognitivismo e aperture alla biosemiotica. La concezione di Propp si differenzia dall\u2019assunto sul primato del sistema e della dimensione sincronica, per rivalutare l\u2019evoluzione diacronica della struttura narrativa e tematica della fiaba. In base a quest\u2019idea, le strutture narrative non sono il prodotto di una combinatoria, ma il prodotto di una lunga stratificazione culturale. Una prova decisiva consiste in alcune fiabe, citate dallo stesso Propp, dalla struttura fortemente anomala perfino se analizzate con gli strumenti della semiotica narrativa contemporanea (schema e percorso narrativo canonico), le quali sarebbero pi\uf9 antiche, secondo criteri chiari ed espliciti di datazione. Riconsiderare la generalit\ue0 dello schema narrativo canonico in quanto modello di riferimento avrebbe, come contropartita, la possibilit\ue0 di indagare con strumenti morfogenetici la nostra preistoria culturale, con potenzialit\ue0 pari a quelle la linguistica diacronica continua a dimostrare ancor oggi

Quadri anatomo-istomorfologici su tiroidi di equini normalmente macellati e loro valutazione ai fini di eventuali trattamenti con tireostatici.

Gli Autori descrivono i quadri anatomo-istopatologici colti a carico di tiroidi di equini regolarmente macellati per valutare una possibile somministrazione di sostanze antiormonali utilizzate anche a scopo auxinico