Essential bounds of Dirichlet polynomials

In this paper we have given conditions on exponential polynomials Pn(s) of Dirichlet type to be attained the equality between each of two pairs of bounds, called essential bounds, aPn (s), ρN and bPn (s), ρ0 associated with Pn(s). The reciprocal question has been also treated. The bounds aPn (s), bPn (s) are defined as the end-points of the minimal closed and bounded real interval I = [aPn (s), bPn (s)] such that all the zeros of Pn(s) are contained in the strip I × R of the complex plane C. The bounds ρN , ρ0 are defined as the unique real solutions of Henry equations of Pn(s). Some applications to the partial sums of the Riemann zeta function have been also showed

On the lower bounds of the partial sums of a Dirichlet series

In this paper it is shown that for the ordinary Dirichlet series, ∑∞j=0αj(j+1)s, α0=1, of a class, say P, that contains in particular the series that define the Riemann zeta and the Dirichlet eta functions, there exists limn→∞ρn/n, where the ρn’s are the Henry lower bounds of the partial sums of the given Dirichlet series, Pn(s)=∑n−1j=0αj(j+1)s, n>2. Likewise it is given an estimate of the above limit. For the series of P having positive coefficients it is shown the existence of the limn→∞aPn(s)/n, where the aPn(s)’s are the lowest bounds of the real parts of the zeros of the partial sums. Furthermore it has been proved that limn→∞aPn(s)/n=limn→∞ρn/n.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature

Low-Coherence Interferometry Using Microwave Photonics for Multilayered Samples

[EN] A photonic structure is proposed by exploiting the advantages of the Microwave Photonics technology over conventional low coherence interferometry. The proposed scheme is based in the analysis of the interference pattern of an incoherent optical signal which is amplitude modulated and transmitted through a dispersive element. The strategic allocation of an interferometric structure combined with balanced photodetection are used to improve the system performance compared to the previous proposals. To the best of our knowledge, an exhaustive theoretical analysis and an experimental demonstration of the structure for multilayered samples are provided in this paper.This work was supported in part by the Ministerio de Ciencia y Tecnologia under Project TEC2014-60378 and in part by the Generalitat Valenciana under the regional Project PROMETEO 2017/103 TECNOLOGIAS Y APLICACIONES FUTURAS DE LA FOTONICA DE MICROONDAS.Benítez-González, J.; Mora Almerich, J. (2018). Low-Coherence Interferometry Using Microwave Photonics for Multilayered Samples. Journal of Lightwave Technology. 36(19):4611-4617. https://doi.org/10.1109/JLT.2018.282709846114617361

Advanced RF Interferometry Structure for Improving Operation Range

© 2018 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] In this letter, a novel structure combining low coherence interferometry (LCI) and microwave photonics (MWP) is proposed. In this case, the electro-optic modulator is strategically placed inside the interferometric structure in order to modify the behavior of the whole MWP-LCI system. Specifically, limiting effects which are inherently generated as the DC term, the self-reflection term and the carrier suppression effect are avoided. This fact enables the improvement of the MWP-LCI operating range in comparison to previous proposals. Moreover, a detailed description of the MWP-LCI structure is addressed in this letter to support the corresponding experimental demonstration and theoretical development. In addition, typical LCI capabilities such as penetration depth, resolution, and sensitivity are also measured. For the MWP-LCI structure proposed here, a 1 cm penetration depth with a resolution of 120 mu m and a sensitivity beyond 50 dB are achieved.This work was supported in part by the National Project TEC2014-60378 through the Ministerio de Ciencia y Tecnologia and in part by the Regional Project PROMETEO FASE II/2013/012 through the Generalitat Valenciana. (Corresponding author: J. Mora.)Benítez-González, J.; Mora Almerich, J. (2018). Advanced RF Interferometry Structure for Improving Operation Range. IEEE Photonics Technology Letters. 30(18):1637-1640. https://doi.org/10.1109/LPT.2018.2865005S16371640301

Sensitivity Enhancement for Low-Coherence Interferometry

[EN] In this letter, a sensitivity improvement for systems combining low-coherence interferometry (LCI) and microwave photonics (MWP) is demonstrated. This improvement is due to the introduction of a different modulation format and an exhaustive control of the optical source profile compared with previous MWP-LCI schemes. Our proposal allows to retrieve the visibility of low-coherence interferograms through the analysis of the interference pattern using a dispersive element. We demonstrate that the use of a phase modulator offers better stability and lower insertion loss since a bias point configuration is not needed compared with the intensity modulators typically used in these schemes. The process for controlling the optical source profile permits a comparison between uniform and Gaussian profiles. In this way, the limiting effects of the sidelobes over the achieved sensitivity level are analyzed. The proposed MWP-LCI structure is experimentally demonstrated through the characterization of the electrical transfer function. In this case, a maximum sensitivity of 65 dB is achieved in our MWP-LCI structure showing a 30-dB improvement compared with current proposals.This work was supported in part by the National Project through the Ministerio de Ciencia y Tecnologia under Grant TEC2014-60378-C2-1-R and in part by the Generalitat Valenciana under Grant PROMETEO FASE II/2013/012. (Corresponding author: J. Mora.)Benítez-González, J.; Mora Almerich, J. (2017). Sensitivity Enhancement for Low-Coherence Interferometry. IEEE Photonics Technology Letters. 29(20):1735-1738. https://doi.org/10.1109/LPT.2017.2748818S17351738292

Efectos de la regulación sobre el funcionamiento de los mercados de gas natural en Colombia

El desarrollo y la consolidación del sector de gas natural en Colombia es reciente y ha cobrado mayor fuerza en los últimos años debido a la importancia de este hidrocarburo como fuente alternativa en la generación eléctrica, gracias al menor costo y al efecto menos contaminante que produce en el ambiente.50 p.Contenido parcial: Descripción del sector de gas natural en Colombia -- Marco regulatorio del sector de gas natural en Colombia -- Análisis de la estructura del sector de gas natural en Colombia -- Problemas de incentivos a que da lugar la regulación

Demonstration of multiplexed sensor system combining low coherence interferometry and microwave photonics

[EN] In this work, a multiplexed sensor system is proposed by means of the combination of low coherence interferometry (LCI) and microwave photonics (MWP). Variations of physical magnitudes can be measured in an array of head sensors by monitoring the optical path difference generated by each sensor. In this case, the characterization of the multiplexed sensor system is done through the electrical transfer function corresponding to the MWP-LCI system. Moreover, the effect produced by the mutual interaction among head sensors is analyzed in this work. Experimental and theoretical demonstration of the system is provided comparing single detection and balanced detection approaches.National Project TEC2014-60378; Research Excellency Award Program GVA PROMETEO 2013/012.Benítez, J.; Bolea, M.; Mora Almerich, J. (2017). Demonstration of multiplexed sensor system combining low coherence interferometry and microwave photonics. Optics Express. 25(11):12182-12187. doi:10.1364/OE.25.012182S1218212187251

La coexistencia de dos estatutos docentes: una aproximación desde la nueva gestión pública

58 páginas : ilustracionesEl presente documento se fijó como objetivo establecer la pertinencia y legalidad de la actual coexistencia de dos estatutos docentes en Colombia (1278 de 2012 y 2277 de 1979) que regulan el ejercicio de esta profesión en el sector oficial, en los niveles de educación preescolar, básica y media, desde la perspectiva de la Nueva Gestión Pública. Para el logro del propósito general, se hace la debida justificación, bajo el análisis de un componente de la Política Pública Educativa, para el caso, la simultaneidad regulatoria. En el Capítulo I, se habla sobre la Metodología, se hace la respectiva explicación de la relevancia de la educación sobre el nivel de desarrollo que logre el país y se describe la problemática surgida a raíz de la actual coexistencia de dos estatutos docentes; El Capítulo 2, toca los aspectos teóricos que fundamentan la investigación; En el Capítulo 3 se describen los dos estatutos docentes vigentes, se comparan y se infiere la legalidad, implicaciones y pertinencia de su coexistencia. Finalmente se presentan las conclusiones derivadas del desarrollo de la investigación. La investigación se adelantó bajo un enfoque cualitativo de tipo documental, privilegiando la consulta de fuentes secundarias y realizando comparaciones y descripciones.The present document set as objective to establish the relevance and legality of the current coexistence of two teaching statutes in Colombia ( 1278of2012 and 2277 of 1979) that regulate the exercise of this profession in the official sector, in the levels of preschool education, basic and middle, from the perspective orthe New Public Management. For the achievement or the general purpose, due justification is made, under the analysis of a component or the Public Educational policy, for the matter the regulatory simultaneity. In Chapter I, the Methodology is discussed, the respective explanation of the relevance of education on the level of development achieved by the country is made, and the problems arising from the current coexistence of two teaching statutes arc described; Chapter 2, touches the theoretical aspects that underlie the investigation; Chapter 3 describes the two current teaching statutes, compares and infer the legality, implications and relevance of their coexistence. Finally, the conclusions derived from the development of the research are presented. The research was carried out under a qua I itative documentary approach, favoring the consultation of secondary sources and making comparisons and descriptions.Magíster en Gobierno y Políticas PúblicasMaestrí

SCM Adaptation to Improve Scanning Rate in RF Interferometry Applications

[FR] In this letter, we present a novel structure for performing subcarrier multiplexing (SCM) to improve the scanning rate in low coherence interferometry (LCI) systems combined with the microwave photonics (MWP) technology. In this MWP-LCI proposal, the optical path differences (OPDs) produced by different samples between the arms of an interferometer are closely related to the central frequency of different RF resonances generated in the RF domain. By the proposed adaptation of the SCM technique, M subcarriers are multiplexed in the modulation stage and each subcarrier is set to sweep simultaneously a concrete part of the spectrum. The complete electrical transfer function of the structure is obtained combining each individual sweep. Therefore, a considerable reduction of the sweep time is provided to collect the complete electrical transfer function. Therefore, the scanning rate is reduced according to the number of subcarriers (M) employed in the multiplexing stage. An OPD range of 8 mm is achieved with a constant resolution of 120 μm in the whole range. Finally, a maximum sensitivity of 60 dB is also reached for that operation range.The research leading to these results was supported by the National Project TEC2014-60378-C2-1-R funded by the Ministerio de Ciencia y Tecnologia and the regional project PROMETEO FASE II/2013/012 funded by the Generalitat Valenciana. (Corresponding author: J. Mora.)Benítez-González, J.; Mora Almerich, J.; Bolea Boluda, M. (2017). SCM Adaptation to Improve Scanning Rate in RF Interferometry Applications. IEEE Photonics Technology Letters. 29(12):999-1002. https://doi.org/10.1109/LPT.2017.2700884S9991002291

High performance low coherence interferometry using SSB modulation

[EN] Low coherence interferometry (LCI) is an optical measurement technique that has attracted the interest for relevant fields like medicine or sensing. With the objective of improving LCI capabilities, microwave photonics (MWP) arises as an innovative technology to enhance LCI possibilities. In this letter, a novel MWP-LCI approach is proposed and experimentally demonstrated to measure the optical path difference (OPD) of a sample. The operation principle of the technique is based on the analysis of the interference pattern through a dispersive element to retrieve its visibility using a vector network analyzer. Different capabilities of the system in terms of sensitivity, resolution, and SNR have been proved. In this case, the proposal is able to avoid carrier-suppression effect leading to a sensitivity improvement of 20 dB in comparison with previous structures for certain values of the OPD. Moreover, the OPD range has been extended up to 10 mm achieving an invariant resolution over all operation range. Finally, the improvement of the SNR of the system has been experimentally demonstrated by controlling properly the RF resonance profile through the adjustment of the optical source power distribution. We have observed an improvement of the dynamic range close to 40 dB for a Gaussian profile.This work was supported in part by the National Project funded by the Ministerio de Ciencia y Tecnologia under Grant TEC2014-60378-C2-1-R and in part by the Regional Project PROMETEO FASE under funded by the Generalitat Valenciana Grant II/2013/012.Benítez-González, J.; Bolea Boluda, M.; Mora Almerich, J. (2017). High performance low coherence interferometry using SSB modulation. IEEE Photonics Technology Letters. 29(1):90-93. https://doi.org/10.1109/LPT.2016.2628963S909329