Pamplona, Navarra, Spain

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Department of Nutrition, Food Science and Physiology
780
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Division of Gene Therapy and Hepatology
1,388
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IESE Business School
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Publication History View all

  • [Show abstract] [Hide abstract]
    ABSTRACT: This work presents an automatic method for distortion correction and calibration of intra-operative spine x-ray images, a fundamental step for the use of this modality in computer and robotic assisted surgeries. Our method is based on a prototype calibration drum, attached to the c-arm intensifier during the intervention. The projections of its embedded fiducial beads onto the x-ray images are segmented by the proposed method, which uses its calculated centroids to undo the distortion and, afterwards, calibrate the c-arm. For the latter purpose, we propose the use of a constrained version of the well known Direct Linear Transform (DLT) algorithm, reducing its degrees of freedom from 11 to 3. Experimental evaluation of our method is included in this work, showing that it is fast and more accurate than other existing methods. The low segmentation error level also ensures accurate calibration of the c-arm, with an expected error of 4% in the computation of its focal distance.
    Computerized Medical Imaging and Graphics 10/2014; 38(7). DOI:10.1016/j.compmedimag.2014.06.004
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    ABSTRACT: The application of high heating rates in tempering treatments can provide a valuable tool for refining carbide sizes, mainly those located at high angle grain boundaries. This work analyses the influence of heating rates ranging from 1 to 300 °C/s during the tempering treatment of a 0.42%C low alloy steel. The results indicate that when high heating rates are combined with short holding times, predicting hardness will require the inclusion of the heating up and cooling down cycles in addition to the holding time and temperature used in the definition of the conventional Hollomon–Jaffe tempering parameter (TP). The effect of heating rate on carbide size distribution has been quantified, distinguishing between particles located at high (HAB) and low (LAB) misorientation angle boundaries. The former correspond to those carbides nucleated at prior γ grain, martensite block or packet boundaries whereas the latter refer to those nucleated within martensite laths and at lath boundaries. The refinement obtained has been evaluated from the point of view of hardness behaviour.
    Materials and Design 10/2014; 62:296–304. DOI:10.1016/j.matdes.2014.05.053
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    ABSTRACT: Ultrasound-assisted synthesis of biodiesel is a well known process that has been widely used in recent years. A reduction of the processing time and the amount of required catalyst as well as the possibility to work at room temperature have been achieved in most cases. Normally, the use of ultrasound replaces the conventional agitation and heating required to establish close contact between the two immiscible phases involved in this reaction (triglycerides and methanol). However, it may be not sufficient depending on the type of oil. In the present study, transesterification of oils with very different fatty acids composition has been conducted by combination of sonication and agitation cycles either at room temperature or at 50 °C. Application of ultrasound was carried out with an ultrasonic probe at 20 kHz frequency, 70% duty cycle and 50% amplitude. The experimental designs were planned by using the response surface methodology intended to find optimal values allowing a significant saving in the amount of catalyst and total reaction time required. Thus, oils with high content of unsaturated fatty acids (e.g. rapeseed and soybean oils) were found to reach biodiesel yields higher than the minimum value provided by the standard EN 14103 in shorter reaction times (below 15 min) compared to traditional transesterification. On the contrary, oils with high content of saturated fatty acids (e.g. coconut and palm oils) did not reach the required yield of 96.5% w/w. Finally, it may be concluded there is a positive influence of stirring and heating at reaction temperature between consecutive ultrasonic cycles on FAME yield and properties.
    Fuel 09/2014; 131:6–16. DOI:10.1016/j.fuel.2014.04.066

Information

  • Address
    Pio XII, 53, 31008, Pamplona, Navarra, Spain
  • Head of Institution
    D. Alfonso Sánchez-Tabernero
  • Website
    http://www.unav.edu
  • Phone
    +34 948425600
Information provided on this web page is aggregated encyclopedic and bibliographical information relating to the named institution. Information provided is not approved by the institution itself. The institution’s logo (and/or other graphical identification, such as a coat of arms) is used only to identify the institution in a nominal way. Under certain jurisdictions it may be property of the institution.

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Top publications last week by downloads

 
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Nature 03/2015; 519(7543):344. DOI:10.1038/nature14283,
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