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Institution

Romanian Academy

ArchiveBucharest, Romania
About: Romanian Academy is a archive organization based out in Bucharest, Romania. It is known for research contribution in the topics: Population & Nonlinear system. The organization has 3662 authors who have published 10491 publications receiving 146447 citations. The organization is also known as: Academia Română & Societatea Literară Română.


Papers
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TL;DR: In this article, an e-periodic structure formed by two interwoven and connected components which stand for the fissure system and the porous matrix is considered and the corresponding homogenized system is exactly that proposed by Barenblatt and al.
Abstract: We consider an e-periodic structure formed by two interwoven and connected components which stand for the fissure system and the porous matrix. We assume that on the matrix-fissure interface the pressure has a jump of order e-1 with respect to the fluid flux which is continuous. We prove that the corresponding homogenized system is exactly that proposed by Barenblatt and al. [1].

51 citations

Journal ArticleDOI
TL;DR: In this paper, the existence of C 0 -solutions for a class of nonlinear evolution equations subjected to nonlocal initial conditions is proved. But the existence is not yet proven for the case of continuous functions.
Abstract: We prove the existence of C 0 -solutions for a class of nonlinear evolution equations subjected to nonlocal initial conditions, of the form: { u ′ ( t ) + A u ( t ) ∋ f ( t ) f ( t ) ∈ F ( t , u ( t ) ) u ( 0 ) = g ( u ) , where A : D ( A ) ⊆ X ↝ X is an m -accretive operator acting on the infinite-dimensional Banach space X , F : [ 0 , 2 π ] × D ( A ) ¯ ↝ X is an almost strongly weakly u.s.c. multi-function which satisfies an appropriate “sign” condition, while g : C ( [ 0 , 2 π ] ; D ( A ) ¯ ) → D ( A ) ¯ is a continuous function.

51 citations

Journal ArticleDOI
TL;DR: In this paper, the pyrolysis of plastic and thermoset fractions (keyboards, casings, printed circuit boards, and mixtures thereof) of used computers was studied by thermogravimetry and batch reactor pyrolys.
Abstract: The increasing production of computers, the progress in their performance, and the shorter time between innovation and production has led to increasing numbers of obsolete products. It has thus become necessary to recover some materials from old computers and to protect the environment from a new type of pollution. Such recycling is difficult because of the diversity of polymeric materials used, e.g., thermoplastics (polystyrene or acrylonitrile-butadiene-styrene) and thermosets (epoxy resins), and the relatively high levels of flame retardants (halogen- and nitrogen-containing compounds) added during production. Pyrolysis seems to be a suitable way to recover materials and energy from such waste without component separation if an efficient method for reducing toxic compounds can be applied. In this study, the pyrolysis of plastic and thermoset fractions (keyboards, casings, printed circuit boards, and mixtures thereof) of used computers was studied by thermogravimetry and batch reactor pyrolysis. The degradation products were separated into three fractions, solid, liquid, and gaseous, each of them being characterized by suitable methods such as gas chromatography (GC-MSD, gas chromatography-mass spectrometry detection; GC-AED, gas chromatography-atomic emission detection), infrared (FT-IR) and 1H-NMR (nuclear magnetic resonanace) spectroscopy, and elemental analysis. It has been established that most of the halogens, nitrogen, and sulfur is concentrated in the residue. However, the elimination of hazardous toxic compounds, mainly those containing bromine, is necessary before being able to safely use the pyrolysis oils as fuels or in refinery or petrochemical industry flows.

51 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present new results of an experimental study on the explosion characteristics: the explosion pressure, the rate of pressure rise (or the deflagration index), the explosion delay time and the laminar burning velocity for ethanol/air mixtures with ethanol concentrations between 3.5 and 20.0vol% in the presence of various diluents (nitrogen, exhaust gas, water and carbon dioxide with dilution concentrations from 0 to 20vol%), at various initial pressures from 0.25 bar to 1.0bar and at an initial temperature of 373

51 citations

Journal ArticleDOI
TL;DR: In this article, a combined approach of the standardized precipitation index (SPI) and the climatic water deficit (WD) was used to characterize droughts in Romania using the approach of both the SPI and WD.
Abstract: This paper characterizes droughts in Romania using the approach of both the standardized precipitation index (SPI) and climatic water deficit (WD). The values of the main climatic factors (rainfall, temperature, reference evapotranspiration, etc.) were obtained from 192 weather stations in various regions of Romania. Penman–Monteith reference evapotranspiration (ETo-PM) was used to calculate WD as the difference between precipitation (P) and ETo-PM. SPI was calculated from precipitation values. There is a clear difference between drought and aridity. Drought occurrence determines higher WD values for plains and plateaus and lower climatic excess water (EW) values for high mountains in Romania, depending on the aridity of the specific region considered and drought severity. WD calculated as mean values for both normal conditions and, for all locations studied, various types of drought was correlated with mean annual precipitation and temperature, respectively. The combined approach of WD and SPI was mainly carried out for periods of 1 year, but such studies could also be done for shorter periods like months, quarters, or growing season. The most arid regions did not necessarily coincide with areas of the most severe drought, as there were no correlations between WD and SPI and no altitude-based SPI zones around the Carpathian Mountains, as is the case for other climate characteristics, soils and vegetation. Water resource problems arise where both SPI values characterize extremely droughty periods and WD values are greatly below −200 mm/year. This combined use of SPI and WD characterizes the dryness of a region better than one factor alone and should be used for better management of water in agriculture in Romania and also other countries with similar climate characteristics.

51 citations


Authors

Showing all 3740 results

NameH-indexPapersCitations
Cristina Popescu7428518434
Adrian Covic7357017379
Gheorghe Paun6539918513
Floriana Tuna6027111968
Arto Salomaa5637417706
Jan A. Bergstra5561613436
Alexandru T. Balaban5360514225
Cristian Sminchisescu5317312268
Maya Simionescu4719210608
Marius Andruh462398431
Werner Scheid465189186
Vicenţiu D. Rădulescu463607771
Cornelia Vasile442977108
Irinel Popescu444018448
Mihail Barboiu442395789
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202335
2022113
2021671
2020690
2019704
2018630