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Evaluation of the effective thermal conductivity of composite polymers by considering the filler size distribution law

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第5期10卷 704-709页

作者： sorin HOLOTESCU Floriana D. STOIAN Department of Thermal Machines Technology and Transportation "Politehnica" University of TimisoaraTimisoara RO-300222 Romania

We present an empirical model for the effective thermal conductivity (ETC) of a polymer composite that includes dependency on the filler size distribution-chosen as the Rosin-Rammler distribution. The ETC is determined based on certain hypotheses that connect the behavior of a real composite material A, to that of a model composite material B, filled with mono-dimensional filler. The application of these hypotheses to the Maxwell model for ETC is presented. The validation of the new model and its characteristic equation was carried out using experimental data from the reference. The comparison showed that by using the size distribution law a very good fit between the equation of the new model (the size distribution model for the ETC) and the reference experimental results is obtained, even for high volume fractions, up to about 50%.

关键词： Effective thermal conductivity (ETC) Filler size distribution Equivalent volume fraction Composite polymer

Bingham Flows in Periodic Domains of Infinite Length

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Chinese Annals of Mathematics,Series B 2018年第2期39卷 183-200页

作者： Patrizia DONATO sorin MARDARE Bogdan VERNESCU Dedicated to Philippe G. Ciarlet on the occasion of his 80th birthda

The Bingham fluid model has been successfully used in modeling a large class of non-Newtonian fluids. In this paper, the authors extend to the case of Bingham fluids the results previously obtained by Chipot and Mardare, who studied the asymptotics of the Stokes flow in a cylindrical domain that becomes unbounded in one direction, and prove the convergence of the solution to the Bingham problem in a finite periodic domain, to the solution of the Bingham problem in the infinite periodic domain, as the length of the finite domain goes to infinity. As a consequence of this convergence, the existence of a solution to a Bingham problem in the infinite periodic domain is obtained, and the uniqueness of the velocity field for this problem is also shown. Finally, they show that the error in approximating the velocity field in the infinite domain with the velocity in a periodic domain of length 2l has a polynomial decay in , unlike in the Stokes case （see [Chipot, M. and Mardare, S., Asymptotic behaviour of the Stokes problem in cylinders becoming unbounded in one direction, Journal de Mathgmatiques Pures et Appliqudes, 90（2）, 2008, 133-159]） where it has an exponential decay. This is in itself an important result for the numerical simulations of non-Newtonian flows in long tubes.

关键词： Bingham fluids Variational inequalities

APPROXIMATION BY COMPLEX SZSZ-DURRMEYER OPERATORS IN COMPACT DISKS

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Acta Mathematica Scientia 2014年第4期34卷 1157-1165页

作者： sorin G.GAL Vijay GUPTA Department of Mathematics and Computer Science University of Oradea Str. Universitatii No. 1410087 OradeaRomania Department of Mathematics Netaji Subhas Institute of Technology Sector 3 DwarkaNew Delhi-110078India

In the present paper, we deal with the complex Szasz-Durrmeyer operators and study Voronovskaja type results with quantitative estimates for these operators attached to analytic functions of exponential growth on comp... 详细信息

关键词： complex Szasz-Durrmeyer operators Voronovksaja type result exact order of approximation in compact disks simultaneous approximation

Using experimental data to reduce the single-building sigma of fragility curves:case study of the BRD tower in Bucharest,Romania

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Earthquake Engineering and Engineering Vibration 2013年第4期12卷 643-658页

作者： Matthieu Perrault Philippe Gueguen Alexandru Aldea sorin Demetriu Institut des Sciences de la Terre Université Joseph Fourier Grenoble ICNRS/IFSTTAR Technical University of Civil Engineering

The lack of knowledge concerning modelling existing buildings leads to significant variability in fragility curves for single or grouped existing buildings. This study aims to investigate the uncertainties of fragility curves, with special consideration of the single-building sigma. Experimental data and simplified models are applied to the BRD tower in Bucharest, Romania, a RC building with permanent instrumentation. A three-step methodology is applied：（1） adjustment of a linear MDOF model for experimental modal analysis using a Timoshenko beam model and based on Anderson＇s criteria, （2） computation of the structure＇s response to a large set of accelerograms simulated by SIMQKE software, considering twelve ground motion parameters as intensity measurements （IM）, and （3） construction of the fragility curves by comparing numerical interstory drift with the threshold criteria provided by the Hazus methodology for the slight damage state. By introducing experimental data into the model, uncertainty is reduced to 0.02 considering Sd ） as seismic intensity IM and uncertainty related to the model is assessed at 0.03. These values must be compared with the total uncertainty value of around 0.7 provided by the Hazus methodology.

关键词： vulnerability fragility curves uncertainty slight damage Timoshenko model Bucharest

Deactivation of Streptococcus mutans Biofilms on a Tooth Surface Using He Dielectric Barrier Discharge at Atmospheric Pressure

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Plasma Science and Technology 2013年第6期15卷 535-541页

作者： Imola MOLNAR Judit PAPP Alpar SIMON sorin Dan ANGHEL Babes-Bolyai University Faculty of Biology and GeologyCluj-Napoca 400015Romania Babes-Bolyai University Faculty of PhysicsCluj-Napoca 400084Romania

This paper presents a study of the effect of the low temperature atmospheric helium dielectric barrier discharge（DBD） on the Streptococcus mutans biofilms formed on tooth surface. Pig jaws were also treated by plasma to detect if there is any harmful effect on the *** plasma was characterized by using optical emission *** data indicated that the discharge is very effective in deactivating Streptococcus mutans *** can destroy them with an average decimal reduction time（D-time） of 19 s and about 98%of thein were killed after a treatment time of 30 *** to the survival curve kinetic an overall 32 s treatment time would be necessary to perform a complete *** experimental results presented in this study indicated that the helium dielectric barrier discharge,in plan-parallel electrode configuration,could be a very effective tool for deactivation of oral bacteria and might be a promising technique in various dental clinical applications.

关键词： Streptococcus mutans dielectric barrier discharge plasma treatment biofilm deactivation sterilization

High-resolution impedance mapping using electrically activated quantitative phase imaging

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Light(Science & Applications) 2021年第2期10卷 186-196页

作者： Cristina Polonschii Mihaela Gheorghiu sorin David Szilveszter Gáspár sorin Melinte Hassaan Majeed Mikhail E.Kandel Gabriel Popescu Eugen Gheorghiu International Centre of Biodynamics 060101 BucharestRomania Institute of Information and Communication Technologies Electronics and Applied MathematicsUniversite Catholique de Louvain1348 Louvain-la-NeuveBelgium Quantitative Light Imaging Laboratory Beckman Institute for Advanced Science and TechnologyUniversity of Illinois at Urbana-ChampaignUrbanaIL 61801USA

Retrieving electrical impedance maps at the nanoscale rapidly via nondestructive inspection with a high signal-to-noise ratio is an unmet need,likely to impact various applications from biomedicine to energy *** this study,we develop a multimodal functional imaging instrument that is characterized by the dual capability of impedance mapping and phase quantitation,high spatial resolution,and low temporal *** achieve this,we advance a quantitative phase imaging system,referred to as epi-magnified image spatial spectrum microscopy combined with electrical actuation,to provide complementary maps of the optical path and electrical *** demonstrate our system with high-resolution maps of optical path differences and electrical impedance variations that can distinguish nanosized,semi-transparent,structured coatings involving two materials with relatively similar electrical *** map heterogeneous interfaces corresponding to an indium tin oxide layer exposed by holes with diameters as small as~550 nm in a titanium(dioxide)over-layer deposited on a glass *** show that electrical modulation during the phase imaging of a macro-electrode is decisive for retrieving electrical impedance distributions with submicron spatial resolution-and beyond the limitations of electrode-based technologies(surface or scanning technologies).The findings,which are substantiated by a theoretical model that fits the experimental data very well enable achieving electro-optical maps with high spatial and temporal *** virtues and limitations of the novel optoelectrochemical method that provides grounds for a wider range of electrically modulated optical methods for measuring the electric field locally are critically discussed.

关键词： impedance resolution phase

Recovery of Immersions from Their Metric Tensors and Nonlinear Korn Inequalities:A Brief Survey

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Chinese Annals of Mathematics,Series B 2017年第1期38卷 253-280页

作者： Philippe G.CIARLET Cristinel MARDARE sorin MARDARE Department of Mathematics City University of Hong Kong83 Tat Chee AvenueKowloonHong Kong. Sorbonne Universites Universite Pierre et Marie CurieLaboratoire Jacques-Louis LionsCNRS-UMR7598F-7.5005 Laboratoire de Mathematiques Raphael Salem UMR 6085 CNRS-Universite de Rouen Avenue de l'Universite BP.12 Technopole du Madrillet F76801

The authors discuss the existence and uniqueness up to isometries of Enof immersions φ : Ω  R^n→ E^n with prescribed metric tensor field(g ij) : Ω→ S^n>, and discuss the continuity of the mapping(gij) →φ defined in this fashion with respect to various topologies. In particular, the case where the function spaces have little regularity is considered. How, in some cases, the continuity of the mapping(gij) →φ can be obtained by means of nonlinear Korn inequalities is shown.

关键词： Isometric immersions Nonlinear Korn inequalities Metric tensor

Predictors of rebleeding and in-hospital mortality in patients with nonvariceal upper digestive bleeding

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World Journal of Clinical Cases 2019年第18期7卷 2687-2703页

作者： Daniela Cornelia Lazar sorin Ursoniu Adrian Goldis Department of Internal Medicine I University Medical ClinicUniversity of Medicine and Pharmacy "Victor Babes"Timisoara 300041Timis CountyRomania Department of Public Health and Health Management University of Medicine and Pharmacy "Victor Babes"Timisoara 300041Timis CountyRomania Department of Gastroenterology and Hepatology University of Medicine and Pharmacy "Victor Babes"Timisoara 300041Timis CountyRomania

BACKGROUND Nonvariceal upper digestive bleeding (NVUDB) represents a severe emergency condition and is associated with significant morbidity and mortality. Despite a decrease in the incidence due to the widespread use of potent therapy with proton pump inhibitors as well as the implementation of modern endoscopic techniques, the mortality rate associated with NVUDB is still high. AIM To identify the clinical, biological, and endoscopic parameters associated with a poor outcome in patients with NVUDB to allow the stratification of risk, which will lead to the implementation of the most accurate management. METHODS We performed a retrospective study including patients who were admitted to the Gastroenterology Department of Clinical Emergency County Hospital Timisoara, Romania, with a diagnosis of NVUDB between 1 January 2008 and 31 December 2016. All the data were collected from the patient’s records, including demographic data, medication history, hemodynamic status, paraclinical tests, and endoscopic features as well as the methods of hemostasis, rate of rebleeding, need for surgery and death;we also assessed the Rockall score of the patients, length of hospitalization and associated comorbidities. All these parameters were evaluated as potential risk factors associated with rebleeding and death in patients with *** We included a batch of 1581 patients with NVUDB, including 523 (33%) females and 1058 (67%) males with a median age of 66 years. The main cause of NVUDB was peptic ulcer (73% of patients). More than one-third of the patients needed endoscopic treatment. Rebleeding rate was 7.72%;surgery due to failure of endoscopic hemostasis was needed in 3.22% of cases;the in-hospital mortality rate was 8.09%, and the bleeding-episode-related mortality rate was 2.97%. Although our predictive models for rebleeding and death had a low sensitivity, the specificity was very high, suggesting a better discriminative capacity for identifying patients with better out

关键词： Nonvariceal upper digestive bleeding Risk factors Rebleeding Death Outcome

Design of Flexible and Self-Standing Electrodes for Li-lon Batteries

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Chinese Journal of Chemistry 2017年第1期35卷 41-47页

作者： Jean-Pierre Bourgeois Alexandru Vlad sorin Melinte Jean-Frangois Gohy Institute of Condensed Matter and Nanosciences Universite catholique de Louvain Place Louis Pasteur 1 1348 Louvain-la-Neuve Belgium Electrical Engineering/ICTEAM Universite catholique de Louvain Place du Levant 3 1348 Louvain-la-Neuve Belgium

Flexible portable electronic devices have attracted increasing attention during the last decade. Energy consumption of such devices is ever increasing and performing power sources, that are moreover flexible, need to be developed to seamlessly integrate into such architectures. While lithium-ion batteries appear to be the best solution to meet the power and energy requirements, their structural and mechanical considerations still need to be addressed. Here, we realize and study the impact on the electrochemical performances of carbon nanotubes （CNTs） based, current collector-free and binder-free, Li-ion battery electrodes. Multi-walled carbon nanotubes acting as a mechanical and electron conductive scaffold enable structural flexibility and good electrochemical performances. Flexible Li-ion cells made with such electrodes show promising performances while being realized through simple manu- facturing approaches.

关键词： Li-ion batteries carbon nanotubes flexible batteries lithium cobalt oxide lithium titanium oxide