Rogelio Durán - Academia.edu (original) (raw)

Papers by Rogelio Durán

Research paper thumbnail of Thermal properties of a series of side-chain liquid crystalline poly(methacrylates)

Journal de Physique, 1988

2014 Le comportement thermique d'une série homologue de poly(méthacrylates) liquides cristallins ... more 2014 Le comportement thermique d'une série homologue de poly(méthacrylates) liquides cristallins à groupes mésogènes latéraux a été étudié par thermogravimétrie, analyse thermique différentielle, microscopie optique en lumière polarisée et dilatométrie. L'étude menée par DSC a permis de montrer que l'équilibre n'est atteint que lentement même au-dessus de la température de transition vitreuse. Le polymorphisme thermotrope des polymères a été analysé en fonction de la longueur de l'espaceur souple. Les transitions vitreuses mises en évidence ont été discutées. La dilatométrie a permis de calculer les volumes spécifiques partiels des espaceurs souples et de montrer que, dans l'état mésomorphe vitreux, ces espaceurs sont proches de l'état cristallin ; que, dans l'état isotrope, ils sont à l'etat liquide ; alors que, dans l'état mésomorphe normal, ils sont dans un état « intermédiaire » entre l'état cristallin et l'état liquide. Abstract. 2014 The thermal behaviour of a series of side-chain liquid crystalline poly(methacrylates) has been investigated by thermogravimetry, differential scanning calorimetry, polarizing optical microscopy, and dilatometry. The DSC study has shown that long times are required to reach equilibrium even at temperatures above the glass transition. The thermotropic polymorphism has been determined as a function of the length of the flexible spacer. Glass transitions in the mesomorphic state have been discussed. Dilatometry has shown that, for the « glassy » mesomorphic phases, the partial specific volume of the flexible spacer is close to that corresponding to the crystalline state ; that, for the normal liquid crystalline phases, it is intermediate between those corresponding to the crystal and the isotropic liquid ; and that, for the isotropic polymer, it is close to that of a liquid.

Research paper thumbnail of BWR online monitoring system based on noise analysis

Nuclear Engineering and Design, 2006

A monitoring system for during operation early detection of an anomaly and/or faulty behavior of ... more A monitoring system for during operation early detection of an anomaly and/or faulty behavior of equipment and systems related to the dynamics of a boiling water reactor (BWR) has been developed. The monitoring system is based on the analysis of the "noise" or fluctuations of a signal from a sensor or measurement device. An efficient prime factor algorithm to compute the fast Fourier transform allows the continuous, real-time comparison of the normalized power spectrum density function of the signal against previously stored reference patterns in a continuously evolving matrix. The monitoring system has been successfully tested offline. Four examples of the application of the monitoring system to the detection and diagnostic of faulty equipment behavior are presented in this work: the detection of two different events of partial blockage at the jet pump inlet nozzle, miss-calibration of a recirculation mass flow sensor, and detection of a faulty data acquisition card. The events occurred at the two BWR Units of the Laguna Verde Nuclear Power Plant. The monitoring system and its possible coupling to the data and processing information system of the Laguna Verde Nuclear Power Plant are described. The signal processing methodology is presented along with the introduction of the application of the evolutionary matrix concept for determining the base signature of reactor equipment or component and the detection of off normal operation conditions.

Research paper thumbnail of Strategy to develop a new system to assist BWR's operations

Transactions of the American Nuclear Society, 2007

Research paper thumbnail of Thermal properties of a series of side-chain liquid crystalline poly(methacrylates)

Journal de Physique, 1988

2014 Le comportement thermique d'une série homologue de poly(méthacrylates) liquides cristallins ... more 2014 Le comportement thermique d'une série homologue de poly(méthacrylates) liquides cristallins à groupes mésogènes latéraux a été étudié par thermogravimétrie, analyse thermique différentielle, microscopie optique en lumière polarisée et dilatométrie. L'étude menée par DSC a permis de montrer que l'équilibre n'est atteint que lentement même au-dessus de la température de transition vitreuse. Le polymorphisme thermotrope des polymères a été analysé en fonction de la longueur de l'espaceur souple. Les transitions vitreuses mises en évidence ont été discutées. La dilatométrie a permis de calculer les volumes spécifiques partiels des espaceurs souples et de montrer que, dans l'état mésomorphe vitreux, ces espaceurs sont proches de l'état cristallin ; que, dans l'état isotrope, ils sont à l'etat liquide ; alors que, dans l'état mésomorphe normal, ils sont dans un état « intermédiaire » entre l'état cristallin et l'état liquide. Abstract. 2014 The thermal behaviour of a series of side-chain liquid crystalline poly(methacrylates) has been investigated by thermogravimetry, differential scanning calorimetry, polarizing optical microscopy, and dilatometry. The DSC study has shown that long times are required to reach equilibrium even at temperatures above the glass transition. The thermotropic polymorphism has been determined as a function of the length of the flexible spacer. Glass transitions in the mesomorphic state have been discussed. Dilatometry has shown that, for the « glassy » mesomorphic phases, the partial specific volume of the flexible spacer is close to that corresponding to the crystalline state ; that, for the normal liquid crystalline phases, it is intermediate between those corresponding to the crystal and the isotropic liquid ; and that, for the isotropic polymer, it is close to that of a liquid.

Research paper thumbnail of BWR online monitoring system based on noise analysis

Nuclear Engineering and Design, 2006

A monitoring system for during operation early detection of an anomaly and/or faulty behavior of ... more A monitoring system for during operation early detection of an anomaly and/or faulty behavior of equipment and systems related to the dynamics of a boiling water reactor (BWR) has been developed. The monitoring system is based on the analysis of the "noise" or fluctuations of a signal from a sensor or measurement device. An efficient prime factor algorithm to compute the fast Fourier transform allows the continuous, real-time comparison of the normalized power spectrum density function of the signal against previously stored reference patterns in a continuously evolving matrix. The monitoring system has been successfully tested offline. Four examples of the application of the monitoring system to the detection and diagnostic of faulty equipment behavior are presented in this work: the detection of two different events of partial blockage at the jet pump inlet nozzle, miss-calibration of a recirculation mass flow sensor, and detection of a faulty data acquisition card. The events occurred at the two BWR Units of the Laguna Verde Nuclear Power Plant. The monitoring system and its possible coupling to the data and processing information system of the Laguna Verde Nuclear Power Plant are described. The signal processing methodology is presented along with the introduction of the application of the evolutionary matrix concept for determining the base signature of reactor equipment or component and the detection of off normal operation conditions.

Research paper thumbnail of Strategy to develop a new system to assist BWR's operations

Transactions of the American Nuclear Society, 2007