Exact solutions for equilibrium configurations of charged conducting liquid jets

A wide class of exact solutions is obtained for the problem of finding the equilibrium configurations of charged jets of a conducting liquid; these configurations correspond to the finite-amplitude azimuthal deformations of the surface of a round jet. A critical value of the linear electric charge density is determined, for which the jet surface becomes self-intersecting, and the jet splits into two. It exceeds the density value required for the excitation of the linear azimuthal instability of the round jet. Hence, there exists a range of linear charge density values, where our solutions may be stable with respect to small azimuthal perturbations.Comment: 7 pages, 5 figures, to appear in Physical Review

Future Development of Renewable Energy in Russia: A Case of Solar Power

Currently, there is a growing number of studies related to assessing the cost-effectiveness of renewable energy projects around the world. This topic is also very relevant for the Russian energy market that is otherwise dominated by oil and gas. The Russian Ministry of Energy forecasts that local power plants running on the renewable energy sources (RES) may not become economically efficient until 2025 or later. However, a research question arises: Is it possible to effectively implement RES projects in Russia without any state support? In order to answer this question, the authors need to assess the economic feasibility of seven scenarios for the construction of a solar power plant in the Orenburg region of Russia. The methodological basis of this work is the widely used in the energy sector classic method of investment analysis based on the calculation of discounted indicators: net present value (NPV), payback period (DPP) and internal rate of return (IRR) of the project. All our calculations are based on industry-specific initial capital investment estimates, energy storage equipment costs, and related annual operating costs. This led to the development of the scenarios on the basis of an analysis of the features of electricity and capacity generation in the Orenburg region, the existing options for joining the trading system of the energy market, energy storage applications, as well as the availability of the Russian government support and funding for the solar energy projects. Our results demonstrate that the economic feasibility of the development of renewable energy in Russia can become a reality. Out of the seven scenarios, three yielded the positive economic outcome (among them there were the two project scenarios without government support). These two projects featured the sale of electricity in retail markets and the installation of an additional energy storage system, despite an almost twofold increase in capital investments. The projects in question achieved the best economic results according to the three calculated criteria. In particular, the scenario that provided for the work on the retail market directly to the energy consumer receives an NPV of more than 1.5 times higher than other projects, an IRR of 10% and pays off at least 3 years faster. Achieving a positive economic result in the wholesale market was possible only in case of state support for the project. In addition, this scenario of the project numerically reached almost identical indicators, as in the case of selling energy on the retail market in the region where the power facility operates: NPV is almost 127 million rubles, IRR is within 13.9%, and DPP is 15 years. Other scenarios that do not provide for the use of energy storage systems or do not have state support for working in the wholesale market are not self-sustaining even during the 25-year life of energy equipment. These results might have practical significance and will be used in developing an approach to creating a profile of regions in terms of the advancements of renewable energy, as well as in developing strategies for the incentives of this sector in Russia. Copyright © 2022 Rausser, Chebotareva, Smutka, Strielkowski and Shiryaeva.Government Council on Grants, Russian Federatio

Revealing Renewable Energy Perspectives via the Analysis of the Wholesale Electricity Market

The wholesale electricity and capacity market constitute the backbone of the Russian power industry. It is in this market that large suppliers and buyers operate, and its entire turnover is consequently transmitted to the retail market. Our paper presents a theoretical overview of the main tools for forming the cost of electricity and capacity in the wholesale market in Russia (depending on the regional affiliation), the type of end users, and the degree of state participation. We consider the specifics of the formation of the cost of electricity and capacity in the price and non-price wholesale markets of Russia, which differ in territorial, climatic, and economic characteristics, as well as the established structure of generation. In the empirical part of the paper, we carry out a structural analysis of the volumes of trade in electricity and capacity in the price and non-price zones of the market. Furthermore, we explain the reasons for the current dynamics of prices in the wholesale market. Using the obtained results, we calculate the maximum annual effect of the solar power plant operation in various zones of the Russian wholesale market, as well as in the retail market. In addition, we estimate the economic incentive for the transition of the functioning of power facilities from the wholesale to the retail market. Our results can be of considerable practical importance and might be used for improving the strategy for the development of the electric power industry at the regional level both in Russia and in the other countries. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.This work was supported by a grant from the President of the Russian Federation (MK-4549.2021.2)

Respiratorni simptomi u radnica na preradi riba na obali Jadrana u Hrvatskoj

This article describes respiratory symptoms and lung function in 98 fish processing female workers employed in a fish processing plant located on the Croatian Adriatic coast and 95 matching controls. The study included chronic and acute respiratory symptoms which developed during the shifts. Lung function measurements included forced vital capacity (FVC), one-second forced expiratory volume (FEV1) and maximal expiratory rates at 50 % and the last 25 % (FEF50, FEF25). Chronic respiratory symptoms were significantly dominant in fish processing workers compared to controls. The most common chronic symptoms were hoarseness (57.1 %), nasal catarrh (51.0 %), chronic cough (42.9 %), chronic phlegm (34.7 %), and frequent chest cold (35.7 %). Exposed smokers and nonsmokers had a similar prevalence of chronic respiratory symptoms. Acute symptoms over the work shift were high, with headache in lead (smokers: 62.5 %; nonsmokers: 56.1 %). Most of the ventilatory capacity parameters were significantly lower than predicted, FEF25 in particular, indicating obstructive changes predominantly in the smaller airways. These findings suggest that fish processing workers are prone to developing acute and chronic respiratory symptoms as well as to lung function changes. This calls for medical and technical preventive measures to be introduced in the work environment of the fi sh processing plant.Cilj je ovoga istraživanja bio ispitati respiratorne simptome i plućnu funkciju radnica zaposlenih na preradi riba u industriji na obali Jadranskog mora u Hrvatskoj. U istraživanje je uključeno 98 radnica zaposlenih na preradi riba i 95 žena neizložene kontrolne skupine. Ispitivani su kronični i akutni respiratorni simptomi koji se razvijaju tijekom radne smjene. Mjerena je plućna funkcija registriranjem forsiranoga vitalnog kapaciteta (FVC), forsiranoga ekspiracijskog volumena u prvoj sekundi (FEV1) te maksimalnoga ekspiracijskog protoka pri 50 % i zadnjih 25 % forsiranoga vitalnog kapaciteta (FEF50, FEF25) na krivulji maksimalni ekspiracijski protok-volumen (MEPV). Učestalost većine kroničnih respiracijskih simptoma bila je značajno viša u eksponiranih u usporedbi s kontrolnom skupinom. U eksponiranih radnica utvrđena je i visoka prevalencija akutnih simptoma koji se razvijaju tijekom radne smjene, posebno za promuklost (57,1 %) i katar nosa (51 %), potom slijedi kronični kašalj (42,9 %), kronični iskašljaj (34,7 %), upale sinusa (32 %) i česte prehlade (35,7 %). S obzirom na naviku pušenja pušači i nepušači imali su sličnu prevalenciju kroničnih respiratornih simptoma. Izložene radnice imale su visoku prevalenciju akutnih simptoma tijekom radne smjene i to naročito za glavobolju (pušači 62,5 %; nepušači 56,1 %). Ventilacijska funkcija pluća bila je značajno smanjena u usporedbi s predviđenim normalnim vrijednostima posebice za FEF25 % upućujući na opstruktivne promjene pretežno u manjim dišnim putovima. Naši podaci upućuju na opasnost razvoja kroničnih i akutnih respiracijskih simptoma i promjena plućne funkcije u radnika koji rade u industriji na preradi riba. Medicinske i tehničke preventivne mjere u radnom okolišu treba preporučiti u industriji prerade riba

Theory of rotating electrohydrodynamic flows in a liquid film

The mathematical model of rotating electrohydrodynamic flows in a thin suspended liquid film is proposed and studied. The flows are driven by the given difference of potentials in one direction and constant external electric field E-out in another direction in the plane of a film. To derive the model, we employ the spatial averaging over the normal coordinate to a film that leads to the average Reynolds stress that is proportional to vertical bar E-out vertical bar(3). This stress generates tangential velocity in the vicinity of the edges of a film that, in turn, causes the rotational motion of a liquid. The proposed model is used to explain the experimental observations of the liquid film motor