1,867 research outputs found

    Supersymmetric CP-violating Currents and Electroweak Baryogenesis

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    In this work we compute the CP-violating currents of the right-handed stops and Higgsinos, induced by the presence of non-trivial vacuum expectation values of the Higgs fields within the context of the minimal supersymmetric extension of the Standard Model (MSSM) with explicit CP-violating phases. Using the Keldysh formalism, we perform the computation of the currents at finite temperature, in an expansion of derivatives of the Higgs fields. Contrary to previous works, we implement a resummation of the Higgs mass insertion effects to all orders in perturbation theory. While the components of the right-handed stop current j^\mu_{\widetilde t_R} become proportional to the difference H_2 \partial^{\mu}H_1-H_1 \partial^{\mu} H_2 (suppressed by \Delta\beta), the Higgsino currents, j^\mu_{\widetilde{H}_i}, present contributions proportional to both H_2 \partial^{\mu}H_1\pm H_1 \partial^{\mu} H_2. For large values of the charged Higgs mass and moderate values of \tan\beta the contribution to the source proportional to H_2 \partial^{\mu}H_1+H_1 \partial^{\mu} H_2 in the diffusion equations become sizeable, although it is suppressed by the Higgsino number violating interaction rate \Gamma_\mu^{-1/2}. For small values of the wall velocity, 0.04\simlt v_\omega \simlt 0.1, the total contribution leads to acceptable values of the baryon asymmetry for values of the CP-violating phases \phi_{CP} in the range 0.04\simlt|\sin\phi_{CP}|\simlt 1. Finally, we comment on the relevance of the latest results of Higgs searches at LEP2 for the mechanism of electroweak baryogenesis within the MSSM.Comment: 27 pages, 4 figures, latex2e. Typo corrected and references adde

    Airborne ultrasonic vortex generation using flexible ferroelectrets

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    Cellular ferroelectrets exhibit interesting electromechanical- acoustical characteristics. Their recent appearance and remarkable properties open up new possibilities for the design and development of ultrasonic transducers. In particular, the feasibility of fabricating ultrasonic vortex generators using ferroelectret films is demonstrated in this work. To this end, a transducer prototype was built by gluing the material onto a tangential-helical surface (outer diameter: 40 mm, pitch: 3.45 mm). Experimental results agree well with the theoretical estimation of the pressure and phase of the acoustic field in the near field and far field, which corroborates the potential of ferroelectrets to customize special acoustic fields. Furthermore, the proposed fabrication procedure is inexpensive and represents a new alternative for exploring and analyzing the special characteristics of acoustical helical wavefront

    Algunas soluciones aproximadas para diseños split-plot con matrices de covarianza arbitrarias

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    El presente trabajo revisa con cierto detalle diversos tipos de análisis para diseños split-plot que carecen del mismo número de unidades experimentales dentro de cada grupo y en los que se incumple el supuesto de esfericidad multimuestral. Específicamente, adoptando el enfoque multivariado de aproximar los grados de libertad desarrollado por Johansen (1980) y el procedimiento de aproximación general mejorada corregida basado en Huynh (1980) se muestra cómo obtener análisis robustos y poderosos a la hora de probar los efectos principales y la interacción, así como hipótesis de comparaciones múltiples relacionadas con estos efectos, tanto si se cuenta con una simple variable dependiente asociada con cada una de las medidas repetidas como si se cuenta con más de una

    An advanced control strategy for biological nutrient removal in continuous systems based on pH and ORP sensors

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    [EN] A fuzzy logic-based control system that uses low-cost sensors for controlling and optimizing the biological nitrogen removal in continuous systems has been developed. The novelty of this control system is the use of several pH, ORP, and dissolved oxygen (DO) sensors instead of on-line nitrogen sensors/analyzers. The nitrogen control system was developed and implemented in a UCT pilot plant fed with wastewater from a full-scale plant. The developed nitrification controller allows the effluent ammonium concentration to be maintained below the effluent criteria discharge with the minimum energy consumption. The denitrification process controller allows the energy consumption derived from pumping to be minimized, as the control system only increases the internal recycle flow rate when the anoxic reactor reveals further capacity for denitrification. This advanced control strategy offers an attractive alternative to on-line, nitrogen analyzer-based control systems since it involves lower investment, maintenance, and operational costs that are derived from the instrumentation. (C) 2011 Elsevier B.V. All rights reserved.The authors would like to express their gratitude to the Ministry of Science and Education for the financial support (Project reference CTM2005-06919-C03-01/TECNO). Financial support from Entitat Publica de Sanejament d'Aigues Residuals de la Comunitat Valenciana and Depuracion de Aguas del Mediterraneo is also gratefully acknowledged.Ruano, MV.; Ribes, J.; Seco Torrecillas, A.; Ferrer, J. (2012). An advanced control strategy for biological nutrient removal in continuous systems based on pH and ORP sensors. Chemical Engineering Journal. 183:212-221. https://doi.org/10.1016/j.cej.2011.12.064S21222118

    Medical image modality classification using discrete Bayesian Networks

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    In this paper we propose a complete pipeline for medical image modality classification focused on the application of discrete Bayesian network classifiers. Modality refers to the categorization of biomedical images from the literature according to a previously defined set of image types, such as X-ray, graph or gene sequence. We describe an extensive pipeline starting with feature extraction from images, data combination, pre-processing and a range of different classification techniques and models. We study the expressive power of several image descriptors along with supervised discretization and feature selection to show the performance of discrete Bayesian networks compared to the usual deterministic classifiers used in image classification. We perform an exhaustive experimentation by using the ImageCLEFmed 2013 collection. This problem presents a high number of classes so we propose several hierarchical approaches. In a first set of experiments we evaluate a wide range of parameters for our pipeline along with several classification models. Finally, we perform a comparison by setting up the competition environment between our selected approaches and the best ones of the original competition. Results show that the Bayesian Network classifiers obtain very competitive results. Furthermore, the proposed approach is stable and it can be applied to other problems that present inherent hierarchical structures of classes

    An improved sampling strategy based on trajectory design for application of the Morris method to systems with many input factors

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    [EN] In this paper, a revised version of the Morris approach, which includes an improved sampling strategy based on trajectory design, has been adapted to the screening of the most influential parameters of a fuzzy controller applied to WWTPs. Due to the high number of parameters, a systematic approach has been proposed to apply this improved sampling strategy with low computational demand. In order to find out the proper repetition number of elementary effects of each input factor on model output (EEi) calculations, an iterative and automatic procedure has been applied. The results show that the sampling strategy has a significant effect on the parameter significance ranking and that random sampling could lead to a non-proper coverage of the parameter space. (C) 2012 Elsevier Ltd. All rights reserved.This research study has been supported by the Spanish Research Foundation (CICYT Project reference CTM2005-06919-C03-01/TECNO), which is gratefully acknowledged.Ruano García, MV.; Ribes, J.; Seco Torrecillas, A.; Ferrer, J. (2012). An improved sampling strategy based on trajectory design for application of the Morris method to systems with many input factors. Environmental Modelling & Software. 37:103-109. https://doi.org/10.1016/j.envsoft.2012.03.008S1031093

    Seismic Response of Embankment Dams

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    This study is intended as a contribution towards a better understanding of the seismic response of embankment dams. Laboratory tests for the determination of static and dynamic mechanical properties of the material are described. A parametric study is performed varying the main source of earthquakes, the height of the dam, the type of the materials and the core position (central and upstream sloping core). The dynamic analyses have made possible the identification of hazard scenarios and particularly the evaluation of stability and residual deformation of the dams

    Fluencia de tableros MDF sometidos a carga constante y condiciones cíclicas de humedad relativa. Influencia del revestimiento de superficies

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    Four different strategies of surface coating (based on 80 g m2 melamin impregnated papers) were used on 19 mm thick commercial MDF panels to assess its reological behaviour under cyclic humidity conditions (20ºC 30 % rh-20ºC 90 % rh). Three different levels of stress (20 %, 30 % and 40 %), based on the ultimate load in bending, were used. Tests were conducted by means of the three points load system. For the same stress level, the relative creep of MDF panels was higher than that in particle boards with similar characteristics. This behaviour was just the opposite than the one exhibited by the panels when the comparison is made based on the same level of load (kg) Melamin coating seems to strongly influence the creep behaviour of the raw material, especially when surface and edge coating were combined.Cuatro tipos de acabados superficiales distintos, aplicados sobre tableros MDF comerciales de 19 mm de espesor, son empleados en el estudio del comportamiento reológico de los tableros MDF ante condiciones alternantes de humedad relativa (20ºC/30 % hr-20ºC/90 % hr). Para el análisis del comportamiento reológico de los tableros se consideran tres niveles de tensión distintos (20 %, 30 %y 40 %), calculados en función de la carga última de rotura a flexión. Los ensayos son efectuados aplicando la carga en punto medio. La fluencia relativa de los tableros MDF resulta ser superior a la exhibida por los tableros de partículas de similares características, observándose que los revestimientos melamínicos aplicados superficialmente influyen eficazmente en la mejora de su comportamiento reológico. Cuando la comparación entre tableros MDF y de partículas se efectúa considerando idénticos niveles de carga aplicada en vez de tensión, el resultado de la comparación resulta ser, justamente, el contrario
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