The paper deals with a unit commitment problem of a generation company whose aim is to find the optimal scheduling of a multiunit pump-storage hydro power station, for a short term period in which ...the electricity prices are forecasted. The problem has a mixed-integer nonlinear structure, which makes very hard to handle the corresponding mathematical models. However, modern mixed-integer linear programming (MILP) software tools have reached a high efficiency, both in terms of solution accuracy and computing time. Hence we introduce MILP models of increasing complexity, which allow to accurately represent most of the hydroelectric system characteristics, and turn out to be computationally solvable. In particular we present a model that takes into account the head effects on power production through an enhanced linearization technique, and turns out to be more general and efficient than those available in the literature. The practical behavior of the models is analyzed through computational experiments on real-world data.
The concept of energy community is currently under investigation as it is considered central into the energy transition process. One of the main aspects of the successful implementation of community ...lays in the energy management system that coordinates exchanges among prosumers. This paper deals with the optimal energy management of a local energy community of dc microgrids with electric vehicle charging stations, considering local reserve provided by storage units and vehicle batteries. A two-stage optimal procedure is proposed to assess the optimal scheduling of resources for each community participant. Additionally, the optimal up and down reserve levels able to cover random fluctuations in photovoltaic generation within each EV-based microgrid are determined by a set of specific chance constraints.
The paper presents a fault location procedure for distribution networks based on the wavelet analysis of the fault-generated traveling waves. In particular, the proposed procedure implements the ...continuous wavelet analysis applied to the voltage waveforms recorded during the fault in correspondence of a network bus. In order to improve the wavelet analysis, an algorithm is proposed to build specific mother wavelets inferred from the fault-originated transient waveforms. The performance of the proposed algorithm are analyzed for the case of the IEEE 34-bus test distribution network and compared with those achieved by using the more traditional Morlet mother wavelet.
The paper presents a procedure for fault location in distribution networks, based on the use of the integrated time-frequency wavelet decompositions of the voltage transients associated with the ...fault-originated travelling waves. The proposed analysis of time-frequency wavelet decompositions has been found to improve the identification accuracy of the frequencies associated to the characteristic patterns of a fault location with respect to a sole frequency-domain wavelet analysis. Several laboratory fault tests, carried out by means of a reduced-scale model of a distribution feeder, are used to illustrate the characteristics and assess the performances of the proposed improved procedure. The paper also illustrates the application of the proposed procedure to a transient, originated by a permanent phase-to-phase fault, measured in a real distribution network in which a post-test analysis has identified the faulted branch.
Abstract
Objectives
To compare the efficacy of dolutegravir plus lamivudine dual therapy (DT) with that of dolutegravir plus two NRTIs triple therapy (TT) as switch strategies.
Methods
A multicentre ...cohort of HIV-positive, HBsAg-negative patients with viral suppression (HIV-RNA ≤50 copies/mL) switching to DT or TT was retrospectively selected from the ARCA database. The effect of DT versus TT on virological failure (VF; defined as two consecutive HIV-RNA values >50 copies/mL or one HIV-RNA value ≥200 copies/mL) was evaluated by multivariable Cox regression models, overall and after stratifying for the presence of NRTI resistance-associated mutations (RAMs).
Results
From December 2014 to June 2020, 628 patients were eligible: 118 (18.8%) started tenofovir/emtricitabine/dolutegravir, 306 (48.7%) abacavir/lamivudine/dolutegravir and 204 (32.5%) lamivudine/dolutegravir. The DT group had significantly higher nadir and baseline CD4 counts, a higher duration of viral suppression and a lower prevalence of RAMs at historical genotype. Overall, 41 VF occurred after a median of 1.7 years of follow-up, with a lower, but not statistically significant, rate for DT versus TT, adjusted HR (aHR) = 0.58, 95% CI = 0.25–1.34. However, DT was associated with less VF in the absence of RAMs when compared with tenofovir-based TT (aHR = 0.20, 95% CI = 0.06–0.67), but not with abacavir-based TT (aHR = 0.43, 95% CI = 0.17–1.11). Conversely, in the setting of pre-existing M184V/I, DT showed a trend to increased risk of VF (versus tenofovir-based TT, aHR = 137.50, 95% CI = 4.24–4464.06; versus abacavir-based TT, aHR = 33.88, 95% CI = 1.75–656.47).
Conclusions
Lamivudine/dolutegravir maintenance DT showed similar efficacy to dolutegravir-based TT; however, past M184V/I may favour VF.
•An earth fault protection for unearthed or compensated neutral networks is proposed.•The protection system implements a transient-based fault detection algorithm.•The protection performance is ...satisfactory in presence of underground cable lines.•The results show the promising detection speed of the protection.•The protection sampling rate has a minor impact on the protection performance.
This paper deals with the protection against earth faults in distribution networks with unearthed or compensated neutral. A transient-based protection system is proposed and assessed through electromagnetic transient program (EMTP) simulations. The fault detection algorithm is based on the estimation of the angle between the zero-sequence voltage and current phasors. The estimation is carried out at the dominant transient frequency of the network response within the first milliseconds after the fault. The implementation of an improved filter and a zero-padding process allows for the identification of high resistance faults with a relatively low sampling frequency. An operation zone is proposed and assessed, also for unbalanced or mixed bare and cable line networks. The performances of the protection system are evaluated for a distribution network in both the cases of unearthed and compensated neutral through a Monte Carlo method that considers the fault resistance, incidence angle and fault location variations as random variables in the EMTP simulations.
In this paper an investigation on the performance of a commercial Proton Exchange Membrane (PEM) fuel cell, installed at the laboratory of the University of Bologna, is carried out, taking into ...account the anodic exhaust management and its effects on the flooding phenomenon.
To address the problem of flooding, it is necessary to run periodically the purge process of the Fuel Fell (FC). Indeed, in this study the periodic anodic purge process in dead-end mode has been investigated. This operation is performed by opening a particular control valve, the Outlet Purge Valve (OPV), located along the anodic exhaust line.
The purge process has been analyzed at different FC power output levels. For each FC power level the optimized behavior of the FC operation was found, by regulating the time of flooding.
The aim of this analysis is to optimize the purge process to reduce the amount of hydrogen discharged with water, in order to increase the FC efficiency. An investigation on the benefits in terms of fuel utilization factor and costs, resulting from optimization of the FC purge process, is shown in the paper.
► Experimental investigation on a PEM fuel cell is carried out. ► Anodic exhaust management is performed via a purge valve. ► Various power output set points are considered. ► A significant efficiency gain at part-load is obtained by optimizing the purge times.
Objectives
We evaluated the efficacy and tolerability of lamivudine + dolutegravir in a cohort of HIV‐1 infected, treatment‐experienced patients with undetectable HIV‐RNA.
Methods
Time to treatment ...discontinuation (TD) and virological failure (VF) and their predictors were assessed in a multicenter cohort of HIV‐1 infected patients, starting lamivudine + dolutegravir after reaching viral suppression. Secondary objective was the evaluation of changes in lipid profile, renal and immunological functions at week 48.
Results
We enrolled 206 patients (72.8% male, with 51 years median age), who mainly switched their antiretroviral therapy for simplification (32.5%) or drug toxicity (54.5%). The estimated probability of maintaining virological suppression at 48 and 96 weeks was 98.2% and 95.1%, respectively. VF was independently predicted by cumulative time on antiretroviral therapy. The estimated probability of remaining on lamivudine plus dolutegravir was 86.7% and 80.5% at week 48 and 96, respectively. A significant improvement in immunological function (CD4 count and CD4/CD8 ratio) was evidenced at week 48, as well as a decrease in total cholesterol/HDL ratio, triglycerides and estimated glomerular filtration rate.
Conclusions
Lamivudine plus dolutegravir was effective in maintaining viral suppression in our cohort and led to an improvement in metabolic and immunologic functions.
The paper deals with the solution of the minimum-losses configuration problem of distribution networks including embedded generation by means of a mixed-integer linear programming (MILP) model. A ...model is proposed that takes into account the typical operating constraints of distribution networks (radial configuration, branch ampacity limits, and bus voltage requirements) and the presence of embedded generation. The accuracy of the results and the computational performances of the proposed MILP model are evaluated by using test networks already analyzed in the literature for the problem of interest.
Abstract
Background
Neuropsychiatric symptoms (NPs) have been reported with dolutegravir use. We hypothesized that increasing dolutegravir trough concentrations (Ctrough) and/or polymorphism in the ...SLC22A2 gene, encoding the organic cation transporter-2 (OCT2), which is involved in monoamine clearance in the CNS and is inhibited by dolutegravir, might be associated with NPs.
Methods
A cross-sectional cohort of HIV-positive patients treated with a dolutegravir-containing regimen underwent determination of allelic discrimination for SLC22A2 808 C → A polymorphism and dolutegravir Ctrough. The Symptom Checklist-90-R investigating 10 psychiatric dimensions and reporting a general severity index (GSI), a self-reported questionnaire and the Mini-International Neuropsychiatric Interview were offered to investigate current NPs. The effects of dolutegravir Ctrough and the SLC22A2 gene variant on NPs were explored by multivariable logistic regression.
Results
A cohort of 203 patients was analysed: 71.4% were male, with median age 51 years and 11 years of ART exposure. Median time on dolutegravir was 18 months. Dolutegravir was associated with different antiretroviral combinations (mainly lamivudine, 38.9%, and abacavir/lamivudine, 35.5%). SLC22A2 CA genotype was independently associated with an abnormal GSI adjusted OR (aOR) 2.43; P = 0.072, anxiety (aOR 2.61; P = 0.044), hostility (aOR 3.76; P = 0.012) and with moderate to severe headache (aOR 5.55; P = 0.037), and dolutegravir Ctrough was associated with hostility (fourth versus first quartile aOR 6.70; P = 0.007) and psychoticism (fourth versus first quartile aOR 19.01; P = 0.008). Other NPs were not associated with SLC22A2 polymorphism or dolutegravir Ctrough.
Conclusions
A variant of the OCT2-encoding gene, in addition to or in synergy with higher dolutegravir Ctrough, is associated with a set of NPs observed during dolutegravir therapy.
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