Descemet stripping automated endothelial keratoplasty in Fuchs' corneal endothelial dystrophy: Anterior segment optical coherence tomography and in vivo confocal microscopy analysis

Background: To evaluate the in vivo corneal changes using in vivo confocal microscopy (IVCM) and anterior segment optical coherence tomography (AS-OCT) in patients with Fuchs' dystrophy who underwent Descemet stripping automated endothelial keratoplasty (DSAEK) and the relationship between these changes and the postoperative visual recovery up to 1-year follow-up. Methods: Before DSAEK and 1 day, 3, 6 and 12 months after surgery 31 patients (39 pseudophakic eyes) underwent a complete ophthalmological evaluation including best corrected visual acuity (BCVA), IVCM (subepithelial haze, interface haze, graft thickness) and AS-OCT (graft thickness). Results: Graft thickness measurements by AS-OCT were strongly correlated to those obtained using IVCM at every follow-up stage (intraclass correlation coefficientâ\u88\u88=â\u88\u880.95 to 0.97 between 3 and 12 months, Pâ\u88\u88<â\u88\u880.001 for all coefficients). No correlation between BCVA and graft thickness measured by AS-OCT at any follow-up stage was found, while at 3 and 6 postoperative months the correlations between BCVA and preoperative subepithelial haze (râ\u88\u88=â\u88\u880.61, Pâ\u88\u88<â\u88\u880.001 and râ\u88\u88=â\u88\u880.46, Pâ\u88\u88=â\u88\u880.002), interface haze (râ\u88\u88=â\u88\u880.51, Pâ\u88\u88<â\u88\u880.001 and râ\u88\u88=â\u88\u880.46, Pâ\u88\u88=â\u88\u880.003), postoperative subepithelial haze (râ\u88\u88=â\u88\u880.43, Pâ\u88\u88=â\u88\u880.004 and râ\u88\u88=â\u88\u880.39, Pâ\u88\u88=â\u88\u880.001) were significant. Conclusions: The study confirmed corneal subepithelial haze and interface haze as important factors limiting visual acuity after DSAEK, while graft thickness was not related to BCVA

APPLICATION TO AN ITALIAN DISTRIBUTION SYSTEM OF A MULTIOBJECTIVE OPTIMAL VOLT/VAR CONTROL STRATEGY: IMPROVEMENTS AND MANAGEMENT PROBLEMS

ABSTRAC

Critical Assessment of Feed-In Tariffs and Solar Photovoltaic Development in Vietnam

Vietnam became the world’s third largest market for solar photovoltaic energy in 2020. Especially after the Vietnamese government issued feed-in tariffs for grid-connected solar photovoltaic systems, the installed capacity of solar photovoltaic applications exploded in 2019. From studies carried out in the relevant literature, it can be said that support policies are highly important for the initial development of the renewable energy industry in most countries. This is especially true in emerging countries such as Vietnam. This paper reviews the feed-in tariffs issued and deployed in different regions of Vietnam for grid-connected solar photovoltaic applications. Moreover, the paper takes a closer look at the costs of electricity production from these systems in relation to the feed-in tariffs issued in Vietnam. The results show that the gap between the levelized cost of electricity and the feed-in tariff for solar photovoltaic electricity is relatively high, particularly in regions with a lower irradiation potential

An experimental analysis of power quality in presence of single phase grid connected photovoltaic systems

In this paper, an experimental power quality analysis in presence of single phase grid connected PV systems is performed in a PV system installed at the Department of Electric Engineering of the University of Palermo through a measurement system set up by the Authors. In particular the analysis has been carried out focusing the attention on voltage and current distortion, as the solar radiation varies. The corresponding Total Harmonic Distortions in voltage and current terms are reported and compared with the standards limits. The presence of interharmonic components is also discussed

Technical, Environmental and Economical Aspects of Hybrid Systems Including Renewables and Fuel Cells

In this paper, some configurations including renewables and fuel cells are studied. Technical, environmental and economical aspects are treated in the frame of the EU regulations concerning the ‘emission trading’ issue and the way in which Italy has implemented the relevant EU directive. The study has been carried out considering some architectures including renewables such as photovoltaic and wind with a back up system to increase continuity of supply based on the application of fuel cells and of a hydrogen storage system. Performing several runs with different values of the cost of energy (COE) bought from the network and produced with traditional fuel, it has been observed that, for some of the considered architectures, the breakeven point in terms of COE is about twice the actual values. To draw these and other interesting conclusions, parametric studies, varying the COE bought from the network and considering different architectures have been carried out by means of the software HOMER 2.1 set up by the National Renewable Energy Laboratories (NREL), USA

Adaptive and Dynamic Ant Colony Search Algorithm for Optimal Distribution Systems Reinforcement Strategy

The metaheuristic technique of Ant Colony Search has been revised here in order to deal with dynamic search optimization problems having a large search space and mixed integer variables. The problem to which it has been applied is an electrical distribution systems management problem. This kind of issues is indeed getting increasingly complicated due to the introduction of new energy trading strategies, new environmental constraints and new technologies. In particular, in this paper, the problem of finding the optimal reinforcement strategy to provide reliable and economic service to customers in a given time frame is investigated. Utilities indeed need efficient software tools to take decisions in this new complex scenario. In past times, utilities project the load growth for several years and then estimate when the capacity limit will be exceeded. Designers then consider some feasible alternatives and select the optimal one in terms of performance and costs. In this paper, the Distributed Generation, DG, technology considered in compound solutions with the installation of feeder and substations is viewed as a new option for solving distribution systems capacity problems, along several years. The objective to be minimized is therefore the overall cost of distribution systems reinforcement strategy in a given timeframe. An application on a medium size network is carried out using the proposed technique that allows the identification of optimal paths in extremely large or non-finite spaces. The proposed algorithm uses an adaptive parameter in order to push exploration or exploitation as the search procedure stops in a local minimum. The algorithm allows the easy investigation of these kinds of complex problems, and allows to make useful comparisons as the intervention strategy and type of DG sources vary