Time filter

Source Type

Ursutiu D.,Transylvania University | Samoila C.,Transylvania University | Baltes L.,Transylvania University | Tierean M.,Transylvania University | And 2 more authors.
Journal of Optoelectronics and Advanced Materials | Year: 2013

In this paper is proved the flexibility of LabVIEW (Laboratory Virtual Instrumentation Engineering Workbench) - graphical programming software - when it is used in connection with applications of ultrasound measurements in the field of plastic materials characterization. The ultrasonic measurement was carried out on plastic specimens with immersion method. In the first step the measurement was made in water with a transducer that generates a longitudinal 5 MHz wave. The same measurement was repeated in a magnetic fluid, water diluted. All of the measurements are oriented to obtain necessary data for the FP7- W2P Plastics project development. In Transylvania University laboratory, the measurement setup used was the EPOCH XT device from PARAMETRICS-NDT. The data can be saved on PC like normal TXT files and exported in Excel and LabVIEW. A preliminary application was developed to see the imported data in one Wave Form Graphic (WFG) or XY graph in LabVIEW. This data can be used easy now in idea of needs for future calculus and data computation. The obtained data will be used for the separation process of the polymeric waste immersed in a magnetic fluid.


Iacob N.,Romanian National Institute for Lasers, Plasma and Radiation Physics | Iacob N.,University of Bucharest | Schinteie G.,National Institute of Materials Physics Bucharest | Bartha C.,National Institute of Materials Physics Bucharest | And 3 more authors.
Journal of Physics D: Applied Physics | Year: 2016

A quantitative treatment of the effects of magnetic mutual interactions on the specific absorption rate of a superparamagnetic system of iron oxide nanoparticles coated with oleic acid is reported. The nanoparticle concentration of the considered ferrofluid samples varied from a very low (0.005) to a medium (0.16) value of the volume fraction, whereas the amplitude of the exciting AC magnetic field ranged from 14-35 kA m-1. It was proved that a direct effect of the interparticle interactions resides in the regime of the modified superparamagnetism, dealing, besides the usual increase in the anisotropy energy barrier per nanoparticle, with the decrease in the specific time constant of the relaxation law, usually considered as a material constant. Consequently, the increase in the specific absorption rate versus the volume fraction is significantly diminished in the presence of the interparticle interactions compared to the case of non-interacting superparamagnetic nanoparticles, with direct influence on the magnetic hyperthermia efficiency. © 2016 IOP Publishing Ltd.


Schinteie G.,National Institute of Materials Physics Bucharest | Palade P.,National Institute of Materials Physics Bucharest | Vekas L.,Romanian Academy Timisoara Division | Iacob N.,Romanian National Institute for Lasers, Plasma and Radiation Physics | And 3 more authors.
Journal of Physics D: Applied Physics | Year: 2013

Ferrofluid samples consisting of magnetite nanoparticles (NPs) coated with oleic acid and dispersed in a non-polar organic solvent have been synthesized by chemical routes. Different volume fractions, φ, of magnetic NPs were considered. The overall structural characterization of NPs has been performed by x-ray diffractometry, with lattice parameters and average coherence lengths evaluated via Rietveld refinements. The magnetic properties of different samples have been analysed by SQUID magnetometry and temperature-dependent Mössbauer spectroscopy and finally explained by adequate magnetic relaxation mechanisms. Zero field cooling-field cooling protocols provided useful information about specific volume fraction dependent magnetic relaxation and de-freezing processes, the lack of the Verwey transition and stronger dipolar interactions at higher volume fractions. Anisotropy energies as obtained by both temperature dependent Mössbauer spectroscopy and magnetometry data are compared and a new procedure for a quantitative characterization of the dipolar interactions is proposed. © 2013 IOP Publishing Ltd.


Timko M.,Slovak Academy of Sciences | Kopcansky P.,Slovak Academy of Sciences | Molcan M.,Slovak Academy of Sciences | Tomco L.,Technical University of Košice | And 6 more authors.
Acta Physica Polonica A | Year: 2012

This contribution is devoted to study of dielectric and magnetodielectric properties in transformer oil based magnetic fuid. The dielectric permittivity and their anisotropy at various mutual orientation electric (50 Hz) and magnetic field were shown at the different volume concentrations of nanoparticles at room temperature. The linear increase of dielectric constant with volume concentration was confirmed which is in good agreement with the theoretical Maxwell prediction. The dielectric anisotropy factor g(B; !) is very close to g = 1. The values of permittivity increased with the increase of volume fraction of magnetite nanoparticles. The highest value of anisotropy characterized by deviation of permittivity δε = ε-ε was found for the highest volume concentration which could mean that no aggregation of magnetite nanoparticles had appeared.


Stoian F.D.,Polytechnic University of Timişoara | Holotescu S.,Polytechnic University of Timişoara | Taculescu A.,Romanian Academy Timisoara Division | Marinica O.,Polytechnic University of Timişoara | And 4 more authors.
2013 - 8th International Symposium on Advanced Topics in Electrical Engineering, ATEE 2013 | Year: 2013

Magnetic nanofluids (widely known as ferrofluids or magnetic liquids) have a unique property-they are responsive to the application of a magnetic field, which allows for the possibility of controlling the flow and the convective heat transfer. This paper presents the characteristic thermo-physical, magnetic and dielectric properties of a transformer oil based magnetic nanofluid, specially prepared for use as a cooling and insulating medium in a power transformer. © 2013 IEEE.


Cristea A.,Romanian Academy Timisoara Division | Neagu A.,Victor Babes University of Medicine and Pharmacy Timisoara | Neagu A.,University of Missouri
Computers in Biology and Medicine | Year: 2016

Tissue engineers seek to build living tissue constructs for replacing or repairing damaged tissues. Computational methods foster tissue engineering by pointing out dominant mechanisms involved in shaping multicellular systems. Here we apply the Lattice Boltzmann (LB) method to study the fusion of multicellular constructs. This process is of interest in bioprinting, in which multicellular spheroids or cylinders are embedded in a supportive hydrogel by a computer-controlled device. We simulated post-printing rearrangements of cells, aiming to predict the shape and stability of certain printed structures. To this end, we developed a two-dimensional LB model of a multicellular system in a hydrogel. Our parallel computing code was implemented using the Portable Extensible Toolkit for Scientific Computation (PETSc). To validate the LB model, we simulated the fusion of multicellular cylinders in a contiguous, hexagonal arrangement. Our two-dimensional LB simulation describes the evolution of the transversal cross section of the construct built from three-dimensional multicellular cylinders whose length is much larger than their diameter. Fusion eventually gave rise to a tubular construct, in qualitative agreement with bioprinting experiments. Then we simulated the time course of a defect in a bioprinted tube. To address practical problems encountered in tissue engineering, we also simulated the evolution of a planar construct, as well as of a bulky, perfusable construct made of multicellular cylinders. The agreement with experiments indicates that our LB model captures certain essential features of morphogenesis, and, therefore, it may be used to test new working hypotheses faster and cheaper than in the laboratory. © 2016 Elsevier Ltd.


PubMed | University of Missouri and Romanian Academy Timisoara Division
Type: | Journal: Computers in biology and medicine | Year: 2016

Tissue engineers seek to build living tissue constructs for replacing or repairing damaged tissues. Computational methods foster tissue engineering by pointing out dominant mechanisms involved in shaping multicellular systems. Here we apply the Lattice Boltzmann (LB) method to study the fusion of multicellular constructs. This process is of interest in bioprinting, in which multicellular spheroids or cylinders are embedded in a supportive hydrogel by a computer-controlled device. We simulated post-printing rearrangements of cells, aiming to predict the shape and stability of certain printed structures. To this end, we developed a two-dimensional LB model of a multicellular system in a hydrogel. Our parallel computing code was implemented using the Portable Extensible Toolkit for Scientific Computation (PETSc). To validate the LB model, we simulated the fusion of multicellular cylinders in a contiguous, hexagonal arrangement. Our two-dimensional LB simulation describes the evolution of the transversal cross section of the construct built from three-dimensional multicellular cylinders whose length is much larger than their diameter. Fusion eventually gave rise to a tubular construct, in qualitative agreement with bioprinting experiments. Then we simulated the time course of a defect in a bioprinted tube. To address practical problems encountered in tissue engineering, we also simulated the evolution of a planar construct, as well as of a bulky, perfusable construct made of multicellular cylinders. The agreement with experiments indicates that our LB model captures certain essential features of morphogenesis, and, therefore, it may be used to test new working hypotheses faster and cheaper than in the laboratory.


Cristea A.,Romanian Academy Timisoara Division
Proceedings of the Romanian Academy Series A - Mathematics Physics Technical Sciences Information Science | Year: 2011

The objective of this work is the investigation of the stability and the miscibility gap recovered in finite difference lattice Boltzmann models for two phase liquid - vapour systems. Various equations of state were considered as well as various finite difference schemes. Second order numerical schemes were used to minimize the numerical effects and the spurious velocity in the interface region.

Loading Romanian Academy Timisoara Division collaborators
Loading Romanian Academy Timisoara Division collaborators