Scielo RSS http://bibliotecadigital.uns.edu.ar/rss.php?pid=0327-079320140033&lang=es vol. 44 num. 3 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=S0327-07932014003300001&lng=es&nrm=iso&tlng=es Moisture sorption isotherms for pistachio powder were determined by gravimetric method at temperatures of 15, 25, 35 and 40°C. Some mathematical models were tested to measure the amount of fitness of experimental data. The mathematical analysis proved that Caurie model was the most appropriate one. As well, adsorption-desorption moisture content of pistachio powder were predicted using artificial neural network (ANN) approach. The results showed that, MLP network was able to predict adsorption-desorption moisture content with R² values of 0.998 and 0.992, respectively. Comparison of ANN results with classical sorption isotherm models revealed that ANN modeling had greater accuracy in predicting equilibrium moisture content of pistachio powder. http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932014003300002&lng=es&nrm=iso&tlng=es Peracetic acid (PAA) is a strong oxidant used by the food industry as a sanitizer, in medical area as a disinfectant and by the textiles and paper industries as a bleacher. Its decomposition rate is an important parameter in these applications. The main purpose of this paper is to study the decomposition kinetics of PAA between 25 and 45 °C in solutions with pH 3.11, 5.0 and 7.0. The decomposition of PAA is a first-order reaction for all solutions and temperatures studied. The rate constants were between 2.08⋅10-3 and 9.44⋅10-3 h-1 (pH 3.11), between 2.61⋅10-3 and 16.69⋅10-3 h-1 (pH 5.0) and between 7.50⋅10-3 and 47.63⋅10-3 h-1 (pH 7.0). The activation energy of PAA decomposition in aqueous solutions are 58.36 and 72.89 kJ⋅mol-1 when pH was 3.11 and 5.0, respectively http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932014003300003&lng=es&nrm=iso&tlng=es The efficiencies of three extraction methods (percolation, Soxhlet and ultrasonically assisted extraction) were evaluated for the extraction of antioxidants from Vicia faba L. bean and hulls. Antioxidant activities of extracts were evaluated using four different tests. Total phenolic and flavonoid contents of the extracts were determined using the Folin-Ciocalteu and aluminium chloride methods, respectively. Although the yield of extractions for ultrasonically assisted extraction was about half to one-fourth of that of other methods, the extraction ratio of total phenol was higher. Hull extracts had higher total phenolic and flavonoid contents and antioxidant activities than bean extracts. The hull ultrasonic extract showed the best DPPH (IC50= 56.9 ± 2.5 mg ml-1) and NO radical scavenging (11.3 ± 0.5 mgml-1). The hull percolation extract showed the best iron chelating ability (171.8 ± 6.8 mg ml-1) and reducing power. The results indicated that all extraction methods could effectively extract antioxidants from medicinal plants. http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932014003300004&lng=es&nrm=iso&tlng=es The aim of the present work was to investigate the kinetics of dehydration and rehydration of the open-air dried peas for untreated and pretreated samples. The models of Page, Wang & Singh, Parabolic and Midilli et al. were applied to experimental data during dehydration and the models of Peleg's, Weibull, first-order kinetic and exponential association were used in rehydration experiments and the corresponding parameters of the models were observed. The models of Midilli et al. and Weibull were found as the suitable models for dehydration and rehydration of the peas, respectively. The highest diffusion coefficients with the values of 6.98*10-11 m²s-1 with the blanched peas in the dehydration and 9.98*10-12 m²s-1 with the salted peas in the rehydration were achieved. http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932014003300005&lng=es&nrm=iso&tlng=es This study aims to implement the predictive multivariable DMC controller in a real plant and compare it to multi-loop PID. The practical application is made in a pilot plant located in the IFES / Serra, where pressure and level are controlled with pump speed and valve opening. Tuning of the DMC controller is obtained through a simulator based on genetic algorithm. The plant responses to step using multi-loop PID and DMC are compared with and without constraints on valve opening and pump speed. The DMC controller is also tested with output restriction (pressure and level). The didactic interface developed with LabVIEW software is used to interact with MATLAB and CompactRIO controller, allowing the use of MATLAB optimization functions in the implementation of the DMC controller. http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932014003300006&lng=es&nrm=iso&tlng=es Given the widespread use of time series classification in many domains, how to improve the accuracy of classification has attracted considerable focus. In this paper, a new similarity measure (SIMscl) based on the global and local information has been proposed for improving the precision rate of one nearest neighbor (1NN) classifier. Specifically, the global information records the intrinsic properties of time series, and is reflected by two indicators: the shape information and the complexity; the local information pays attention to the exact match of value, and is realized by LB_keogh. Simultaneously, a method based on multi-scale discrete haar wavelet transform, key point extraction, and symbolization has been put forward to extract the shape information. To test the efficacy of the proposed shape similarity SIMshape and hybrid similarity SIMscl, the experiments are conducted on two data sets: star light curve and beef. Experimental evaluations show that SIMshape can deal with some time series misclassified by Euclidean Distance (ED), LB_keogh, and Complexity Invariant Distance (CID), and SIMscl has higher precision than ED, LB_keogh, and CID in time series 1NN classification. http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932014003300007&lng=es&nrm=iso&tlng=es Despite a large amount of publications on Fuzzy Mathematical Morphology, little effort was done on systematic evaluation of the performance of this technique. The goal of this work is to compare the robustness against noise of Fuzzy and non Fuzzy Morphological operators when applied to noisy images. Magnetic Resonance Images (MRI) of the brain are a kind of images containing some characteristics that make fuzzy operators an interesting choice, because of their intrinsic noise and imprecision. The robustness was evaluated as the degree in which the results of the operators are not affected by artificial noise in the images. In the analysis we compared different implementation of Fuzzy Mathematical Morphology, and observed that in most of the cases they show higher robustness against noise than the classical morphological operators. http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932014003300008&lng=es&nrm=iso&tlng=es The bundle conductor is often threatened by the wind-excited or wake-induced vibration generated by vortex shedding. So as to simulate the common fluid-structure nonlinear interaction problems in Ultra-High Voltage (UHV) transmission lines, the N-S equations of incompressible viscous fluid with the ALE description has been adopted to formulate the fluid-solid governing equations in the analogue computation and the 2-bundle and 6-bundle sectional models, as well as the deduced finite element discretization scheme of conductor displacement are introduced in the algorithm. Wind tunnel experimental studies are carried out based on the single stranded model, 6-bundle stranded and 6-bundle circle model for the focus of aerodynamic characteristics and the difference between stranded cable and circle cable. Results show that solution of numerical model agrees favorably with experimental results. The aerodynamic coefficients decrease significantly within the expected critical range of wind speed or Reynolds numbers and the cables roughness is not the principle factor to the aerodynamic coefficient when the Reynolds numbers belong to the critical region. However, the interference effect of the bundle conductor widely influenced the wind load applied on the surface of each cable. http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932014003300009&lng=es&nrm=iso&tlng=es This paper presents an Adapted Simulated Annealing (ASA) algorithm to solve an instance of the vehicle routing problem (VRP): the intercity public transport problem (IPTP). This combinatorial optimization problem was effectively solved by means of a robust method. Its performance was achieved thanks to the incorporation of an auxiliary memory and a novel choice of the neighbours. The model is based on initial random solutions capable of generating appropriate bus routes and frequencies in a large solution space. We have established a search strategy that provides excellent responses at the process level. The intercity line linking Bahía Blanca and Punta Alta was chosen with the intention of evaluating ASA performance. The real traffic-behavior has been represented by means of the simulation software called SUMO. The computational results clearly indicate that the proposed approach constitutes an improvement in the ability to search for high quality solutions that facilitates the convergence. http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932014003300110&lng=es&nrm=iso&tlng=es Design of an accurate and robust controller is a challenging topic in an underwater manipulator control. This is due to hydrodynamic disturbances in underwater environment. In this paper a sliding mode control (SMC) included a PID sliding surface and fuzzy tunable gain is designed. In this proposed controller robustness property of SMC and fast response of PID are incorporated with fuzzy rules to reduce error tracking. In the control law, for removing of chattering, the exponential function is used. And also the system is analyzed in terms of stability by direct Lyapunov method. By tuning gains with fuzzy logic, the proposed controller does not require an accurate model of underwater manipulator dynamics. Hence the modeling and simulation studies are done for an underwater manipulator to verify the effectiveness of the proposed method in presence of unmodeled dynamic (variable masses of links) and external disturbance. Both new proposed controller and conventional SMC are simulated. The results of simulation show the high performance of proposed controller in comparison to conventional SMC http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932014003300111&lng=es&nrm=iso&tlng=es In this paper the flexible cable robot tracking is controlled using optimal feedback linearization method. Feedback linearization is used to control the robot within a predefined trajectory while its controlling gains are optimized using LQR method to achieve the maximum payload of the end-effector in presence of flexibilities. Required motors' torque and tracking error caused by flexibility uncertainties are calculated for a predefined trajectory of an under constrained cable robot with six Degrees of Freedom (DOF) and six actuating cables while its cables are considered elastic. Robust controller is also designed and added to the controller to ensure the accuracy and stability of the system and cancel any disturbing effects of the uncertainties. A series of analytic simulation study is done for the mentioned spatial cable robot to show the flexibility effect on dynamic performance of the robot and also prove the superiority of the proposed optimal control strategy to compensate these flexibilities. Finally the results are compared and verified with experimental results of the cable robot of ICaSbot to verify the proposed controlling strategy for controlling the mentioned flexible robot and also prove the correctness of the simulations http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932014003300112&lng=es&nrm=iso&tlng=es This work is a first step in the understanding of the interaction process between internal shock waves and the flow transition inside of a rocket nozzle that develops during the engine start-up phase or when the nozzle is operated at over-expanded conditions. In many cases, this transition in the flow pattern produces side loads in the nozzle due to an asymmetric pressure distribution on the wall, being harmful for the rocket's integrity. To understand this phenomenon, a numerical simulation is performed by solving the three-dimensional Euler equations on unstructured tetrahedral meshes. With this model the computational cost to solve the equations significantly increases, therefore parallel processing is required. Also, an unsteady h-adaptive refinement strategy is used jointly with a Streamline Upwind Petrov-Galerkin and a discontinuity capturing scheme, both to keep the size of the fluid flow problem bounded and to sharply resolve the shock wave pattern. The mesh adaptation strategy is introduced. Since its performance is a major concern in the solution of unsteady flow problems, some implementation issues about the data structure chosen to represent the mesh are discussed. Average pressure distributions computed at the wall and the axis of the nozzle for various pressure ratios are analyzed based on experimental and numerical results from other authors http://bibliotecadigital.uns.edu.ar/scielo.php?script=sci_arttext&pid=S0327-07932014003300113&lng=es&nrm=iso&tlng=es In cytogenetics, karyotype analysis is used to assess the presence of genetic defects by visualization chromosomes structure from microscopic images. A key step in this process is image thresholding, used to detect and extract objects of interest from background, as it affects the performance of further processing steps in image analysis. In this paper, an adaptive local thresholding for Q-band chromosome image segmentation is presented. A re-threshold process based on the Sauvola's local adaptive technique is applied to extract chromosomes from background. Local adaptive histogram equalization is added between thresholding steps to enhance chromosome segments to reduce the chances of pixel misclassification. The proposed thresholding approach provides 93 % of precision, which is better than other similar approaches when evaluated on a reference image dataset