Distance protection and fault location of the PV power plants distribution lines

Unlike the synchronous generators, the short-circuit current provided by the photovoltaic (PV) sources is limited by the grid-connected inverters and closely related to the normal conditions, which impacts the protection of the power systems. This study deals with the protection of the power lines (distribution feeders) that connect the PV power plants (PVPP) to the grid; the first part of this study analyses the impact of the grid-connected PV (GCPV) system on the conventional distance protection. A specific coordination between the over-current protection of the grid side and the distance protection of the PVPP side was used to eliminate this impact. This coordination requires delaying the distance protection and keeping the inverter connected to the grid, which was achieved by fault ride-through (FRT) feature accompanied with the inverter control during the fault condition. The second part studies the possibility of using the double-end-impedance-based fault location on the PVPP power lines, and some FRT strategies were suggested to reduce the effect of the inverter control loops on obtaining the accurate fault location. The proposed work was verified by GCPV system model using MATLAB/Simulink software

Synthesis, Characterization, and Antileishmanial Activity of Certain Quinoline-4-carboxylic Acids

Leishmaniasis is a fatal neglected parasitic disease caused by protozoa of the genus Leishmania and transmitted to humans by different species of phlebotomine sandflies. The disease incidence continues to increase due to lack of vaccines and prophylactic drugs. Drugs commonly used for the treatment are frequently toxic and highly expensive. The problem of these drugs is further complicated by the development of resistance. Thus, there is an urgent need to develop new antileishmanial drug candidates. The aim of this study was to synthesize certain quinoline-4-carboxylic acids, confirm their chemical structures, and evaluate their antileishmanial activity. Pfitzinger reaction was employed to synthesize fifteen quinoline-4-carboxylic acids (Q1-Q15) by reacting equimolar mixtures of isatin derivatives and appropriate α-methyl ketone. The products were purified, and their respective chemical structures were deduced using various spectral tools (IR, MS, 1H NMR, and 13C NMR). Then, they were investigated against L. donovani promastigote (clinical isolate) in different concentration levels (200 μg/mL to 1.56 μg/mL) against sodium stibogluconate and amphotericin B as positive controls. The IC50 for each compound was determined and manipulated statistically. Among these compounds, Q1 (2-methylquinoline-4-carboxylic acid) was found to be the most active in terms of IC50

Evolution of the Late Miocene Mediterranean–Atlantic gateways and their impact on regional and global environmental change

Marine gateways play a critical role in the exchange of water, heat, salt and nutrients between oceans and seas. As a result, changes in gateway geometry can significantly alter both the pattern of global ocean circulation and associated heat transport and climate, as well as having a profound impact on local environmental conditions. Mediterranean–Atlantic marine corridors that pre-date the modern Gibraltar Strait, closed during the Late Miocene and are now exposed on land in northern Morocco and southern Spain. The restriction and closure of these Miocene connections resulted in extreme salinity fluctuations in the Mediterranean, leading to the precipitation of thick evaporites. This event is known as the Messinian Salinity Crisis (MSC). The evolution and closure of the Mediterranean–Atlantic gateways are a critical control on the MSC, but at present the location, geometry and age of these gateways are still highly controversial, as is the impact of changing Mediterranean outflow on Northern Hemisphere circulation. Here, we present a comprehensive overview of the evolution of the Late Miocene gateways and the nature of Mediterranean–Atlantic exchange as deduced from published studies focussed both on the sediments preserved within the fossil corridors and inferences that can be derived from data in the adjacent basins. We also consider the possible impact of evolving exchange on both the Mediterranean and global climate and highlight the main enduring challenges for reconstructing past Mediterranean–Atlantic exchange

Evolution of the Late Miocene Mediterranean–Atlantic gateways and their impact on regional and global environmental change

Marine gateways play a critical role in the exchange of water, heat, salt and nutrients between oceans and seas. As a result, changes in gateway geometry can significantly alter both the pattern of global ocean circulation and associated heat transport and climate, as well as having a profound impact on local environmental conditions. Mediterranean–Atlantic marine corridors that pre-date the modern Gibraltar Strait, closed during the Late Miocene and are now exposed on land in northern Morocco and southern Spain. The restriction and closure of these Miocene connections resulted in extreme salinity fluctuations in the Mediterranean, leading to the precipitation of thick evaporites. This event is known as the Messinian Salinity Crisis (MSC). The evolution and closure of the Mediterranean–Atlantic gateways are a critical control on the MSC, but at present the location, geometry and age of these gateways are still highly controversial, as is the impact of changing Mediterranean outflow on Northern Hemisphere circulation. Here, we present a comprehensive overview of the evolution of the Late Miocene gateways and the nature of Mediterranean–Atlantic exchange as deduced from published studies focussed both on the sediments preserved within the fossil corridors and inferences that can be derived from data in the adjacent basins. We also consider the possible impact of evolving exchange on both the Mediterranean and global climate and highlight the main enduring challenges for reconstructing past Mediterranean–Atlantic exchange