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Timisoara, Romania

Politehnica University of Timișoara is a public university founded on November 11, 1920. Located in Timișoara, Romania, it is one of the largest technical universities in Central and Eastern Europe. Wikipedia.

Dan D.,Polytechnic University of Timisoara
Engineering Structures | Year: 2012

This paper presents the results of an experimental program on two composite shear walls with steel encased profiles (CSRCW), damaged under cyclic lateral loads and thereafter retrofitted and retested. The experimental program was conceived in order to analyze the possibilities of using CFRP materials for strengthening the CSRCW affected by seismic action. The Carbon Fiber Reinforced Polymer (CFRP) composites are becoming more frequently used in strengthening structural elements due to their superior characteristics and simple technology. From the damaged elements obtained in the first phase of the research program, two shear walls with steel encased profiles were selected to be retrofitted and retested. According to a thorough literature survey, the number of experimental campaigns on reinforced concrete walls (RC) retrofitted by FRP composite is rather low, compared to the large number of other structural members, and it does not exist for CSRCW. This paper presents an effective strengthening solution that can be applied to damaged elements to evaluate the availability of partial confinement, applied to parts with locally deteriorated strength. The retrofitting solution uses CFRP strips and plates, to restore the wall bending resistance and to provide a confinement effect at the ends. The experimental results indicate that the performance of the elements CSRCW_R, repaired and retrofitted, was similar to the reference elements in terms of load bearing capacity, but slightly smaller in terms of stiffness and energy dissipation capacities. © 2012 Elsevier Ltd. Source

Irimescu A.,Polytechnic University of Timisoara
Energy | Year: 2011

This paper describes the comparative advantages of using isobutanol as a fuel for SI (spark ignition) engines instead of ethanol. An experimental study of fuel conversion efficiency was performed on a port injection engine fueled with mixtures containing 10, 30 and 50% isobutanol blended with gasoline. Efficiency as well as performance levels were maintained within acceptable limits for all three types of fuel blends compared to running the engine on straight gasoline. These results show that isobutanol is an attractive drop-in fuel for SI engines, and can be blended with gasoline in much higher concentrations compared to ethanol, without any modifications to the fuel system or other engine components. © 2011 Elsevier Ltd. Source

Lelea D.,Polytechnic University of Timisoara
International Journal of Heat and Mass Transfer | Year: 2010

The paper presents the geometric optimization of the micro-heat sink with straight circular microchannels with inner diameter of D i = 900 μm. The inlet cross-section has a rectangular shape and positioned tangentially to the tube axis with the four different geometries. The fluid flow regime is laminar and water with variable fluid properties is used as a working fluid. The heat flux spread through the bottom sink surface is q = 100 W/cm 2. Thermal and hydrodynamic performances of the heat sink are compared with results obtained for conventional channel configuration with lateral inlet/outlet cross-section. Besides, the results are compared with the tangential micro-heat sink with D i = 300 μm. For all the cases, the thermal and hydrodynamic results are compared on a fixed pumping power basis. © 2010 Elsevier Ltd. All rights reserved. Source

Herisanu N.,Polytechnic University of Timisoara
Computers and Mathematics with Applications | Year: 2010

In this paper a new approach combining the features of the homotopy concept with an efficient computational algorithm which provides a simple and rigorous procedure to control the convergence of the solution is proposed to find accurate analytical explicit solutions for some oscillators with discontinuities and a fractional power restoring force which is proportional to sign(x). A very fast convergence to the exact solution was proved, since the second-order approximation lead to very accurate results. Comparisons with numerical results are presented to show the effectiveness of this method. Four numerical applications prove the accuracy of the method, which works very well for the whole range of initial amplitudes. The obtained results prove the validity and efficiency of the method, which can be easily extended to other strongly nonlinear problems. © 2010 Elsevier Ltd. All rights reserved. Source

Lelea D.,Polytechnic University of Timisoara
International Journal of Heat and Mass Transfer | Year: 2011

The numerical modeling of the conjugate heat transfer and fluid flow of Al2O3/water nanofluid through the microchannel heat sink is presented in the paper. The laminar flow regime was considered along with viscous dissipation effect. The microchannel heat sink with square microchannels and Dh = 50 μm is considered. The heat flux was fixed to q = 35 W/m2 with heating and cooling cases. The water based Al 2O3 nanofluid was encountered with various volume concentrations of Al2O3 particles φ=1-9% and three diameters of the particle dp = 13, 28 and 47 nm. The analysis is performed on the results obtained for the local heat transfer coefficients based on a fixed pumping power. The results reveal a different local heat transfer behavior compared to the analysis made on a basis of the constant Re. © 2011 Elsevier Ltd. All rights reserved. Source

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