impact of consumption profile discontinuities on the feasibility of a pv plant

Abstract The revenues of a grid-connected photovoltaic plant are strongly related to the local climatic conditions. In addition, since self-consumed electricity is much more valuable than that traded with the main power grid, also consumption profile plays a key role in the profitability of a PV system. Self-consumption to total PV production ratio depends on the temporal mismatch between energy generation and demand. The amount of energy that is not self-consumed may be very high in the case of a consumption profile with several discontinuities. This study is focused on the analysis of a grid-connected PV system serving a compressed natural gas (CNG) fueling station. These facilities are energy-intensive users, characterized by high variability of electricity demand due to intermittent operation of gas compressors: in a few seconds the total load may change from 100% to 5% and vice versa very frequently during the day. The analysis was based on data acquired on the field for the compression station and those already present in the literature for solar irradiation. The influence on plant design of the time step used for the analysis was studied in detail. The outcomes showed that the typical and well-assessed design approaches of a PV pant may lead to errors when used for the design of systems with several consumption profile discontinuities

Gastroduodenal kinetic activity. Possible role of the duodenal bulb in controlling gastric emptying

The aim of the present study was to evaluate the gastro-duodenal motility coordination, both during the interdigestive phase and after antroduodenal volumetric stimulus. It has been proved that it is possible to evoke the peristaltic gastric activity by stretching the gastric walls. Thus, the Authors simulated the mechanical conditions of the meal by inflating air into the antrum. They studied 5 healthy volunteers, whose age averaged 43 +/- 22.85 years. A 120 cm probe provided with two balloons at 7 and 21 cm from the distal end, and with 7 open-tips for manometric recording, was positioned by endoscopic way. The Authors were able to evaluate the Motor Antral Threshold (i.e. minimum air volume able to evoke an antral motor reflex), obtained by means of the antral inflatable balloon. The average values of this threshold showed to be 35 +/- 5 ml of air. While keeping the duodenal balloon inflated, the repetition of volumetric antral stimulus did not show any Motor Antral Threshold. This threshold showed up again with similar volumes in every patient after deflating the duodenal balloon. The results obtained suggest the existence of a negative duodenal-antral feed-back control on gastric emptying

Microplastics in seawater: sampling strategies, laboratory methodologies, and identification techniques applied to port environment

The European Interreg Italy\u2013France 2014\u20132020 Maritime Project SPlasH! (Stop to Plastics in H2O!) focused on the study of microplastics (MPs) in the marine port environment to evaluate their presence, abundance, and mechanisms of diffusion to the open sea. In the framework of this project, a worldwide review of 74 studies was carried out, providing an overview of MP investigation techniques, focusing on sampling strategies, laboratory methodologies, and identification of MPs collected in seawater, and specifically evaluating their applicability to the marine port environment. Nets were the most commonly used device for MP surface sampling, but their use can be difficult in narrow spaces within the port basins, and they must be coupled to discrete sampling devices to cover all port basins. In the laboratory, density separation (NaCl, ZnCl2, NaI, sodium lauryl sulfate (SLS)), filtration (polycarbonate, polyamide, glass, cellulose, ANOPORE inorganic membrane filters), sieving, visual sorting, and digestion methods (acidic, enzymatic, alkaline, oxidative) were used to separate MPs from seawater. Digestion becomes essential with water samples with great inorganic and organic loads as deriving from a port. Although many studies are based only on visual MP identification under a microscope, analytical identification techniques unequivocally determine the particle nature and the identity of the plastic polymers and are necessary to validate the visual sorting of MPs. Fourier-transform infrared spectroscopy (FTIR) is the most used analytical identification technique