Scielo RSS http://bibliotecadigital.uns.edu.ar/rss.php?pid=0327-079320130022&lang=es vol. 43 num. 2 lang. es http://bibliotecadigital.uns.edu.ar/img/en/fbpelogp.gif http://bibliotecadigital.uns.edu.ar http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200001&lng=es&nrm=iso&tlng=es The maximum entropy method combined with a smoothing restriction was applied to the tomography of a BNC connector using five noisy radiographies from different rotating views. A heuristic control of the filter parameter is constructed by combining the projection error and the global smoothness. The proposed algorithm can be used in cases where the homogeneity of internal material is a priori known from the design and manufacturing processes http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200002&lng=es&nrm=iso&tlng=es In this work, we studied of variable viscosity, Dufour and Soret effects on free convection heat and mass transfer of a non- Newtonian power-law fluid over a vertical full cone in a saturated porous medium in the presence of chemical reaction, non uniform heat generation and thermal radiation. The transformed nonlinear ordinary differential equations are solved numerically using the fourthorder Runge-Kutta method coupled with the shooting method. The influences of various parameters on the local Nusselt number and the local Sherwood number are presented and discussed http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200003&lng=es&nrm=iso&tlng=es The main purpose of this investigation is to study the effect of thermophoresis particle deposition in natural convection heat and mass transfer over a vertical flat plate embedded in a fluid-saturated porous medium with variable viscosity effect. The viscosity of the fluid is assumed to be an inverse linear function of the fluid temperature. A boundary-layer analysis is employed to derive the non-dimensional governing equations. The governing equations for this contribution are transformed into a set of non-similar equations and solved numerically using an implicit finite difference technique. Comparisons with previously published work on special cases of the problem are performed and the results are found to be in excellent agreement. A parametric study illustrating the influence of the thermophoresis parameter, thermophoretic coefficient, viscosity-variation parameter, buoyancy ratio the Lewis number, Prandtl number, transpiration parameter and Grashof number on the fluid velocity, temperature and solute concentration profiles as well as the Sherwood number and the wall thermophoretic deposition velocity is conducted http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200004&lng=es&nrm=iso&tlng=es An analysis of a dual active bridge (DAB) converter under soft-switching mode in the whole operating range is presented in this paper. A detailed study of the impact of the transformer magnetizing inductance, L M, and snubber capacitance, Cxx, parameters on the soft-switching regions is carried out to obtain some design considerations. Simulation and experimental results which validate the theoretical analysis are also presented http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200005&lng=es&nrm=iso&tlng=es The initial carbon deposition and the generation of dehydrogenating selectivity during the initial steps of the reaction are investigated for Pt and PtSn catalysts supported on pure and Na-doped alumina by using a pulse technique (injection of n-butane pulses). Results demonstrate that Pt support-ed on pure alumina is not a proper dehydrogenation catalyst. It shows a high hydrogenolytic and cracking behavior and an important carbon formation that deactivates the catalyst. However the combined presence of tin and sodium inhibits not only the car-bon deposition reactions but also the C-C breaking reactions, increasing in an important way the dehy-drogenating selectivity to the different butenes to a value about 80% http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200006&lng=es&nrm=iso&tlng=es In this work, open-air sun drying of thyme (Thymus Vulgaris) and mint (Mentha Spicata)leaves was investigated. A falling rate period was occurred in drying thyme and mint leaves, starting from the initial moisture content (%73.80 for thyme and %84.70 for mint) to the final moisture content (%7.6 for thyme and %4.85 for mint). Drying times were obtained as 440 for thyme and 420 minutes for mint. L values of fresh and dried herbs were respectively found as 40.25 and 35.70 for thyme and as 44.01 and 33.08 for mint. The effective diffusivities were determined as 2.2571*10-10 m²s-1 for thyme and as 1.2768*10-10 m²s-1 for mint http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200007&lng=es&nrm=iso&tlng=es An attempt has been made to study the Soret effect on an unsteady free convective flow past a vertical plate in slip-flow regime with periodic temperature variation. Analytical solution of the problem has been obtained depending on the physical parameters including the Prandtl number Pr , the Grashof number for heat transfer Gr , the Grashof number for mass transfer Gm , the Schmidt number Sc , the Soret number So etc. The influence of these parameters on velocity field, species concentration field, temperature field, skin-friction and the rate of heat and mass transfer at the plate are discussed graphically http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200008&lng=es&nrm=iso&tlng=es In this study, the chickpea seeds were exposed to ultrasonic irradiation at vibration amplitude setting 40%, 70% and 100% of nominal power for 3 and 10 min at 24 kHz. Water absorption characteristics, moisture content, leaching loss and soaking water conductivity of chickpea at five different soaking temperatures (25, 30, 40, 50 and 60°C) and various soaking times up to 10 h were studied. The soaking rates of treated samples were compared with untreated seeds. Peleg's model was used to describe the hydration kinetics of chickpea seeds during soaking process at different temperatures by weight gain method. Ultrasonic treatment was very effective in water uptake of seeds and was observed that ultrasonic pre-treatment could decrease the soaking time by up to 4 h. The Peleg constant K1 decreased from 10.8×10-3 to 0.99×10-3 h %-1 with increasing temperature from 25 to 60°C and constant K2 increased linearly from 6.72×10-3 %-1 to 9.9×10-3 %-1with increasing the temperature. The leaching loss and conductivity value also increased significantly when the soaking temperature increased. In soaking process, leaching loss changed from 1.66/100 g to 12.27/100 g and conductivity changed from 367 to 1867 µS/cm as soaking temperature increased from 25 to 60°C http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200009&lng=es&nrm=iso&tlng=es The term discretely actuated hyper-redundant manipulator is applied to a kind of manipulators which consists of serially connected modules. Such modules are composed of discretely actuated joints having finite stable states. Since the previous studies have rarely offered satisfactory results regarding the problem of inverse kinematics of discretely actuated hyper-redundant manipulators, the present study is attempting to develop and investigate an effective algorithm to solve this problem. To achieve this, the current research intends to solve the problem of 2D and 3D inverse kinematics of manipulators with many modules, by considering both position and orientation of end frame in real-time with fairly high accuracy. The main ideas of the proposed method are: using mean workspace, breadth-first search with two non-adjacent modules in each step and improving the results by iterating the process. The effectiveness of the presented method is verified through different numerical analyses for various case studies http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200110&lng=es&nrm=iso&tlng=es The crystal structure of two B-type carbonated apatite samples was re-analyzed, using the data of Wilson et al (2006). By applying the least squares method for the determination of carbon and oxygen atoms, a slightly different result was obtained, suggesting that the carbonate ion is not rigorously planar http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200111&lng=es&nrm=iso&tlng=es The conjugate heat transfer and fluid flow of three different water-based nanofluids (Al2O3, CuO, ZnO) through a finned square microchannel heat sink (MCHS) was studied numerically. Three-dimensional numerical simulations were performed considering both laminar flow and viscous dissipation effect along the microchannel. A constant heat flux was assumed on the external surface of the microchannel. The MCHS performance is evaluated in terms of the heat transfer coefficient, pressure drop, and thermal resistance for constant inlet velocity. The results show an increase in the heat transfer and pressure drop for nanofluids, while the thermal resistance of the microchannel decreases. A slight increase for developed Nusselt number is achieved for the finned MCHS in comparison with an unfinned channel http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200112&lng=es&nrm=iso&tlng=es An improved algorithm combining the features of the lattice-Boltzmann and the immersed-boundary methods is presented. Following previous formulations, the method represents a fluid constrained by flexible boundaries by means of a force term acting on the cells adjacent to the boundary, which in turn is moved by the fluid. The present algorithm introduces a more efficient iteration procedure to calculate the fluid-boundary interaction, which facilitates the implementation and improves performance. The simulations were validated against experimental and analytical data showing good agreement and demonstrating the performance of the method to simulate different kind of fluid-solid interaction http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200113&lng=es&nrm=iso&tlng=es Due to its low cost compared with hydroxamate and sulphonate, sodium oleate is employed in direct flotation of low-grade or waste iron ore. However, depressants are being studied. This work shows the influence of the depressant sodium silicate on hematite and quartz flotation with sodium oleate as a collector. Microflotation tests were per-formed in Hallimond tube at pH values 7 and 9, and the zeta potentials of both minerals were determined in the absence and presence of sodium silicate. The sodium silicate was a more efficient depressant for quartz than for hematite, and a selective separation between the two minerals is possible for low reagent concentrations. The zeta potentials of both minerals were shifted to lower values due the specific adsorption of anionic species of sodium silicate onto their surfaces http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200114&lng=es&nrm=iso&tlng=es The finite nature of global fossil fuel resources, high prices and most importantly, their damaging effect on the environment underscore the need to develop alternatives for industrial systems include the cement production process. This industry is classified as energy intensive consumption, so the application of the alternative fuels in cement production can extend fossil fuel supplies and help resolve air pollution problems associated with the use of conventional fuels. This paper proposed to analyze the clinker production from energy and exergy view point, applying the alternative fuel scrap tires with aim of reducing the fossil fuel consumption. The results achieved energy efficiency of 75%, exergy efficiency of 37% with the main irreversibility source provider of rotary kiln http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932013002200115&lng=es&nrm=iso&tlng=es The answer to chemical and biological attacks relies on the ability to monitor and detect the presence of an agent. The aim of this study is to verify the efficacy of a subway smoke extraction system that contains a toxic gas contamination area. A Brazilian subway station located in Rio de Janeiro was selected as a model scenario. Three case studies were examined that activated the SES in exhaustion and ventilation modes. The visualization of the velocity fields and toxic gas concentration profiles showed that when the SES was activated in the extraction mode, it took a few minutes for all of the gas to be taken into the galleries. When the SES was activated in the ventilation mode, the contaminated air was directly disposed into the atmosphere. Therefore, our results show that CFD can be used to propose a contingency plan using the subways' ventilation equipment