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Novi Beograd, Serbia

Vidojevic S.,IHIS Techno experts d.o.o
Advances in Space Research | Year: 2014

Two major effects of Langmuir wave electric field influence on spectral line shapes are appearance of depressions shifted from unperturbed line and an additional dynamical line broadening. More realistic and accurate models of Langmuir waves are needed to study these effects with more confidence. In this article we present distribution shapes of a high-quality data set of Langmuir waves electric field observed by the WIND satellite. Using well developed numerical techniques, the distributions of the empirical measurements are modeled by family of Pearson distributions. The results suggest that the existing theoretical models of energy conversion between an electron beam and surrounding plasma is more complex. If the processes of the Langmuir wave generation are better understood, the influence of Langmuir waves on spectral line shapes could be modeled better. © 2014 Published by Elsevier Ltd.

Martinovic M.M.,University Paris Diderot | Martinovic M.M.,IHIS Techno experts d.o.o | Zaslavsky A.,University Paris Diderot | Maksimovic M.,University Paris Diderot | And 5 more authors.
Journal of Geophysical Research A: Space Physics | Year: 2016

Quasi-thermal noise (QTN) spectroscopy is an accurate technique for in situ measurements of electron density and temperature in space plasmas. A QTN spectrum is determined by plasma and antenna properties. On STEREO/WAVES, since the antennas are relatively short and thick, the QTN spectrum is dominated by electron shot noise, especially at low frequencies, which reduces the accuracy of the method. Here we use the STEREO low-frequency receiver, proton density measured by Plasma and Suprathermal Ion Composition instrument, and a QTN and shot noise models to provide electron temperature data from both STEREO A and B spacecraft. This derivation is important since no reliable measurements of electron temperature exist on board these spacecraft. We compare the results of our analysis with the electron temperature provided by the Wind spacecraft during the period when Wind and STEREO B were close to each other. The comparison shows that our technique is reliable when results are integrated on a time scale of the order of 50 to 60 min. ©2015. American Geophysical Union. All Rights Reserved.

Zaric D.B.,IHIS Techno experts d.o.o | Bulatovic M.L.,University of Belgrade | Rakin M.B.,University of Belgrade | Krunic T.Z.,University of Belgrade | And 2 more authors.
RSC Advances | Year: 2016

The aim of this study was to investigate the survival of probiotics (Lactobacillus acidophilus NCFM, Lactobacillus rhamnosus HN001 and Bifidobacterium lactis HN019) in milk chocolate masses prepared at temperatures 35°C and 40°C. The influence of probiotics and preparation temperature on rheology, particle size distribution and sensory properties of the chocolates, was examined during 6 months of storage at 20 ± 2°C. An inoculation temperature of 40°C significantly improves the rheological and sensory properties of probiotic chocolate, as well as leading to the survival of L. acidophilus NCFM and L. rhamnosus HN001 strains. After 6 months of storage, the survival of these strains was above 90%, with a viable cell count of about 8.1log(CFU g-1). An inoculation temperature of 40°C provides higher scores of overall sensory quality (4.52-4.68), higher quality category (excellent), lower maximal viscosity (for 1.2 Pa s) of chocolates, than a temperature of 35°C. Compared to the chocolate without probiotics, those inoculated at 40°C achieved less increase in volume weighted mean diameter distribution (average 0.8%) than chocolates inoculated at 35°C. Based on the results reported in this paper, seeding of the probiotics in industrial conditions can be done in the mixing tank (at 40°C) before the phase of chocolate shaping. Addition of probiotics at this stage facilitates the manufacturing process, improves the overall quality of chocolate and preserves the probiotics as a key component of this type of product. © The Royal Society of Chemistry 2016.

Simicic M.V.,IHIS Techno experts d.o.o | Govedarica D.D.,University of Novi Sad
Hemijska Industrija | Year: 2011

Internal corrosion of carbon steel pipelines is a major problem encountered in water service. In terms of prediction of the remaining lifetime for water pipelines based on the corrosion allowance, the three main approaches are corrosion modelling, corrosion inhibitor availability, and corrosion monitoring. In this study we used two theoretical corrosion models, Cassandra and Norsok M-506 of quite different origins in order to predict uniform corrosivity of hot aquifers in eight different pipelines. Because of the varying calculation criteria for the different models, these can give very different corrosion rate predictions for the same data input. This is especially true under conditions where the formation of protective films may occur, such as at elevated temperatures. The evaluation of models was conducted by comparison using weight-loss coupons and three corrosion inhibitors were obtained from commercial suppliers. The tests were performed during the 60-day period. Even though inhibitors' efficiencies of 98% had been achieved in laboratory testing, inhibitors' availabilities of 85% have been used due to logistics problems and other issues. The results, given in mmpy, i.e., mm/year, are very consistent with Norsok M-506 prediction. This is presumably because the model considers the effect of the formation of a passive iron carbonate film at temperatures above 80 °C and significant reduction in corrosion rate. Corrosion inhibitor A showed a better performance than inhibitors B and C in all cases but the target corrosion rates of less than 0.1 mmpy were achieved for all inhibitors. The chemical type of corrosion inhibitor A is based on quaternary amines mixed with methanol, isopropyl alcohol, xylene and ethylbenzene. Based on the obtained results the carbon steel lifetime of 30 years, provided proper inhibitors are present and 3mm corrosion allowance, can be achieved for hot aquifers service with presented water compositions.

Pajin B.,University of Novi Sad | Dokic L.,University of Novi Sad | Zaric D.,IHIS Techno experts d.o.o | Soronja-Simovic D.,University of Novi Sad | And 2 more authors.
Journal of Food Engineering | Year: 2013

The aim of this paper is to define the optimal conditions for the pre-crystallization of chocolate produced in a ball mill, that contains 20% soya milk. Chocolate mass and soya milk are refined in a ball mill employing three refining times (30, 60 and 90 min) and pre-crystallization temperatures (26, 28 and 30 °C). Increasing the refining time leads to organized chocolate systems with soya milk. The nucleation time of the system refined for 90 min and pre-crystallized at 30 °C is three times longer compared to that pre-crystallized at 26 °C. By prolonging the refining time, the system becomes dominantly viscous due to the refining and homogenization (tanδ > 1). Taking into consideration all three parameters, i.e., viscosity, yield stress and the area of the thixotropic loop, a refining time of 90 min at the pre-crystallization temperature of 30 °C seems optimal. © 2012 Elsevier Ltd. All rights reserved.

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