Metrology Infrastructure for Energy and Power Quality in DC Railway Systems

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Methodology for the Accurate Measurement of the Power Dissipated by Braking Rheostats

The energy efficiency of transportation is a crucial point for the rail and metro system today. The optimized recovery of the energy provided by the electrical braking can lead to savings of about 10% to 30%. Such figures can be reached by infrastructure measures which allow the recovery of the breaking energy that is not directly consumed by the rail system and dissipated in rheostat resistors. A methodology for the accurate estimate of such energy is valuable for a reliable evaluation of the cost-benefit ratio associated with the infrastructural investment. The energy can be estimated by measuring a braking current flowing in the rheostats. The varying duty-cycle associated with the high dynamic variation, from zero to thousands of amperes, makes the current measurement very challenging. Moreover, the digitization of such waveforms introduces systematic errors that affect the energy estimation. To overcome these issues, this paper proposes a technique to measure the power and energy dissipated by the rheostat of a DC operated train with high accuracy. By means of an accurate model of the electrical braking circuit (chopper and rheostat) and the frequency characterization of the current transducer, a correction coefficient as a function of the duty-cycle is estimated. The method is then applied to data recorded during a measurement campaign performed on-board a 1.5 kV train of Metro de Madrid during normal operation. Using the proposed technique, the estimation of the dissipated braking energy is improved by 20%

Dataset of measured and commented pantograph electric arcs in DC railways

open9sìDC railways are characterized by particularly intense arcing caused by pantograph detachment, due to the large current intensity and the general implementation of onboard resonant filters, whose transient response is triggered by electric transients including electric arcs. Electric arc depends on the train speed (the relative speed between the sliding contact over the pantograph and the hot spot on the catenary system), the intensity of the collected pantograph current and the line voltage level. Electric arcs are broadband in nature and can trigger the system transient response dominated by the resonant filter, besides interfering with the operation of onboard equipment (such as for energy conversion and me tering). (C) 2020 Published by Elsevier Inc.openSignorino, Davide; Giordano, Domenico; Mariscotti, Andrea; Gallo, Daniele; Femine, Antonio Delle; Balic, Fabio; Quintana, Jorge; Donadio, Lorenzo; Biancucci, AlfredoSignorino, Davide; Giordano, Domenico; Mariscotti, Andrea; Gallo, Daniele; Femine, Antonio Delle; Balic, Fabio; Quintana, Jorge; Donadio, Lorenzo; Biancucci, Alfred

Assessment of the Overall Efficiency in WPT Stations for Electric Vehicles

The on-site assessment of the efficiency of a charging station is not a trivial process and is a topic of discussion for professionals. The efficiency of electric Vehicle Supply Equipment (EVSE), is an important parameter for both the user and the EVSE operator. This paper deals with a particular type of EVSE, using static wireless power transfer (WPT). This paper proposes a clear method to account for the parameters which can affect the correct determination of efficiency, such as in particular the accuracy of the meters and the effect of temperature. This work proposes a method to define the accuracy of the power and efficiency on-site assessment, and is aimed at clarifying that despite distorted waveforms at the charging stations, it is possible to reach a good accuracy in a wide temperature span (expanded uncertainty <0.5% between 5∘C and 40∘C). Analysis initiated from the measurement conditions and the actual waveforms recorded at two WPT EVSEs with differently rated power. This paper paves the way for the possibility of verifying class 0.5 meters on-site, desirable for this type of application. The paper also clarifies that despite the evident presence of voltage and current ripple at the batteries, the weight of the ripple power on the total power is nevertheless lower than 0.1%. Finally, the paper highlights how, for the correct measurement of the ripple, it would be advisable to calibrate the instrumentation in DC and in AC, at a frequency double that of the working frequency of the EVSE coil

Correlation between NK function and response to trastuzumab in metastatic breast cancer patients

<p>Abstract</p> <p>Background</p> <p>Trastuzumab is a monoclonal antibody selectively directed against Her2 and approved for the treatment of Her2 overexpressing breast cancer patients. Its proposed mechanisms of action include mediation of antibody-dependent cellular cytotoxicity (ADCC) by triggering FcγRIII on natural killer (NK) cells. This study addresses the correlation between overall NK function and trastuzumab's clinical activity.</p> <p>Subjects and methods</p> <p>Clinical and immunological responses were assessed in 26 patients receiving trastuzumab monotherapy as maintenance management after chemotherapy (8 mg/kg load and then standard doses of 6 mg/kg every 3 weeks). Cytotoxic activity against the MHC class I-negative standard NK target K562 cell line and HER2-specific ADCC against a trastuzumab-coated Her2-positive SKBR3 cell line were assessed in peripheral blood mononuclear cells (PBMC) harvested after the first standard dose. After six months, seventeen patients were scored as responders and nine as non-responders according to the RECIST criteria, while Progression-Free Survival (PFS) was calculated during a 12 months follow-up.</p> <p>Results</p> <p>The responders had significantly higher levels of both NK and ADCC activities (p < 0.05) that were not different from those of eleven normal controls. The NK activity of the non-responders was significantly (p < 0.05) lower than that of the normal controls. At twelve months, there was a marked correlation between PFS and NK activity only. PFS was significantly longer in patients with high levels of NK activity, whereas its pattern was unrelated to high or low ADCC activity.</p> <p>Conclusion</p> <p>One of the mechanisms of action of trastuzumab is NK cell-mediated ADCC lysis of the Her2-positve target cell. We show here that its potency is correlated with the short-term response to treatment, whereas longer protection against tumor expansion seems to be mediated by pure NK activity.</p

“Natural wages dynamics in a Ricardian growth model”

Ricardian growth models are generally built on the assumption of a constant natural wage. Such an assumption conceals the fact that classical economists were aware that in growing economies workers' normal pattern of consumption steadily rise both in terms of quantity and quality. In the first part of the chapter we gather some classical hints on the relationship between economic growth and natural wages in order to provide a rational reconstruction of the classical point of view on natural wage dynamics. In the second part of the chapter we propose a formal analysis of the dynamics of a Ricardian model with endogenous natural wag

Consumption patterns, development and growth: Adam Smith, David Ricardo and Thomas Robert Malthus

In this paper we combine the classical analysis of luxury consumption with the classical theories of development and growth. We also focus on the role played, within classical economics, by institutional factors such as the structure of property rights and contractual arrangements in determining consumption patterns and investment in agriculture. In particular, we show that Ricardo's and Malthus' different views on the role of consumption expenditure in promoting growth depend on Ricardo's acceptance (Malthus' refusal) of Say's law of markets and on Ricardo's exclusion (Malthus' inclusion) of a non-commodity option such as leisure from (in) the range of available consumption alternatives.Structural Change, Long-run Growth, Consumption Pattern, Classical Authors, Luxury Consumption, Property Rights,

Impact of DC Transient Disturbances on Harmonic Performance of Voltage Transformers for AC Railway Applications

: This paper analyzes the impact of typical DC transient events occurring in railway grids on the frequency performance of instrument transformers (ITs) installed onboard trains and in AC substations for power quality (PQ) applications. PQ monitoring in railway systems is an issue of great interest because it plays a key role in the improvement of energy efficiency. The measurement chain for the PQ measurements, at 15 kV at 16.7 Hz and 25 kV at 50/60 Hz, commonly includes ITs to scale the voltage to levels fitting the input of the measurement units. Nevertheless, the behavior of ITs in the presence of PQ phenomena represents an open issue from a normative point of view, even for those installed in conventional AC power supply systems. In this context, the paper presents a possible definition of DC transient disturbances test waveforms, a measurement procedure, and a setup to assess the impact of these disturbances on the harmonic performances of ITs for railway systems. Preliminary experimental tests carried out on two commercial ITs under wide ranges of variation for the amplitude and the time duration of DC disturbances show that, in some cases, the error introduced in harmonic measurements can exceed 100%