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Pedro Ramos Lorente received the M.S. and the Ph.D. degree in telecommunication engineering from University of Zaragoza, Spain, in 1996 and 2005, respectively. From 1997 to 2003, he was an Assistant Lecturer with the Department of Electronics Engineering and Communications of the University of Zaragoza. From 2003 to 2007, he was an Assistant Professor with the same Department. Since 2003, he has been an Associate Professor with the Department of Electronics Engineering and Communications of the University of Zaragoza. In 2008 he was a postdoctoral Research Visitor at laboratory IMS LAPS, University of Bordeaux I (France) under grant “José Castillejo” of the Spanish Government. His research interests include signal processing techniques focused on active noise control and remote measurement of vibrations in large structures. Dr. Ramos is the author of several book chapters, numerous journal papers, and contributions to conference proceedings.
Partial updates (PU) of adaptive filters have been successfully applied in different contexts to lower the computational costs of many control systems. In a PU adaptive algorithm, only a fraction of the coefficients is updated per iteration. Particularly, this idea has been proved as a valid strategy in the active control of periodic noise consisting of a sum of harmonics. The convergence analysis carried out here is based on the periodic nature of the input signal, which makes it possible to formulate the adaptive process with a matrix-based approach, the periodic least-mean-square (P-LMS) algorithm In this paper, we obtain the upper bound that limits the step-size parameter of the sequential PU P-LMS algorithm and compare it to the bound of the full-update P-LMS algorithm. Thus, the limiting value for the step-size parameter is expressed in terms of the step-size gain of the PU algorithm. This gain in step-size is the quotient between the upper bounds ensuring convergence in the following two scenarios: first, when PU are carried out and, second, when every coefficient is updated during every cycle. This step-size gain gives the factor by which the step-size can be multiplied so as to compensate for the convergence speed reduction of the sequential PU algorithm, which is an inherently slower strategy. Results are compared with previous results based on the standard sequential PU LMS formulation. Frequency-dependent notches in the step-size gain are not present with the matrix-based formulation of the P-LMS. Simulated results confirm the expected behavior.
Pedro Ramos Lorente; Raúl Martín Ferrer; Fernando Arranz Martínez; Guillermo Palacios-Navarro. An Alternative Approach to Obtain a New Gain in Step-Size of LMS Filters Dealing with Periodic Signals. Applied Sciences 2021, 11, 5618 .
AMA StylePedro Ramos Lorente, Raúl Martín Ferrer, Fernando Arranz Martínez, Guillermo Palacios-Navarro. An Alternative Approach to Obtain a New Gain in Step-Size of LMS Filters Dealing with Periodic Signals. Applied Sciences. 2021; 11 (12):5618.
Chicago/Turabian StylePedro Ramos Lorente; Raúl Martín Ferrer; Fernando Arranz Martínez; Guillermo Palacios-Navarro. 2021. "An Alternative Approach to Obtain a New Gain in Step-Size of LMS Filters Dealing with Periodic Signals." Applied Sciences 11, no. 12: 5618.
The objective of this study was to evaluate the performance of the different systems and techniques aimed at suppressing vibrations on optical ground-based telescopes. We identified the studies by searching three electronic databases (Science Direct, IEEE library and Web of Science) from the year 2000 to December 2020. The studies were eligible if they proposed systems focused on mitigating the effects of vibrations in optical telescopes and brought performance data. A total of nine studies met our eligibility criteria. Current evidence confirms the feasibility of adaptative optics (AO) systems based on closed-loop control to mitigate vibrations, although variations and additions should be made depending on their nature and characteristics in order to improve the performance of the proposed techniques. This systematic review was conducted to provide a state-of-the-art of the methods and techniques that have been developed over the past two decades. The review also points out some issues that demand future research.
Guillermo Palacios-Navarro; Fernando Arranz Martínez; Raúl Martín Ferrer; Pedro Ramos Lorente. Compensation Techniques Aimed at Mitigating Vibrations in Optical Ground-Based Telescopes: A Systematic Review. Sensors 2021, 21, 3613 .
AMA StyleGuillermo Palacios-Navarro, Fernando Arranz Martínez, Raúl Martín Ferrer, Pedro Ramos Lorente. Compensation Techniques Aimed at Mitigating Vibrations in Optical Ground-Based Telescopes: A Systematic Review. Sensors. 2021; 21 (11):3613.
Chicago/Turabian StyleGuillermo Palacios-Navarro; Fernando Arranz Martínez; Raúl Martín Ferrer; Pedro Ramos Lorente. 2021. "Compensation Techniques Aimed at Mitigating Vibrations in Optical Ground-Based Telescopes: A Systematic Review." Sensors 21, no. 11: 3613.
The COVID-19 pandemic has changed people’s lives and the way in which certain services are provided. Such changes are not uncommon in healthcare services and they will have to adapt to the new situation by increasing the number of services remotely offered. Limited mobility has resulted in interruption of treatments that traditionally have been administered through face-to-face modalities, especially those related to cognitive impairments. In this telerehabilitation approach, both the patient and the specialist physician enter a virtual reality (VR) environment where they can interact in real time through avatars. A spaced retrieval (SR) task is implemented in the system to analyze cognitive performance. An experimental group (n = 20) performed the SR task in telerehabilitation mode, whereas a control group (n = 20) performed the SR task through a traditional face-to-face mode. The obtained results showed that it is possible to carry out cognitive rehabilitation processes through a telerehabilitation modality in conjunction with VR. The cost-effectiveness of the system will also contribute to making healthcare systems more efficient, overcoming both geographical and temporal limitations.
José Varela-Aldás; Jorge Buele; Pedro Ramos Lorente; Iván García-Magariño; Guillermo Palacios-Navarro. A Virtual Reality-Based Cognitive TeleRehabilitation System for Use in the COVID-19 Pandemic. Sustainability 2021, 13, 2183 .
AMA StyleJosé Varela-Aldás, Jorge Buele, Pedro Ramos Lorente, Iván García-Magariño, Guillermo Palacios-Navarro. A Virtual Reality-Based Cognitive TeleRehabilitation System for Use in the COVID-19 Pandemic. Sustainability. 2021; 13 (4):2183.
Chicago/Turabian StyleJosé Varela-Aldás; Jorge Buele; Pedro Ramos Lorente; Iván García-Magariño; Guillermo Palacios-Navarro. 2021. "A Virtual Reality-Based Cognitive TeleRehabilitation System for Use in the COVID-19 Pandemic." Sustainability 13, no. 4: 2183.
In the field of active noise control (ANC), a popular method is the modified filtered-x LMS algorithm. However, it has two drawbacks: its computational complexity higher than that of the conventional FxLMS, and its convergence rate that could still be improved. Therefore, we propose an adaptive strategy which aims at speeding up the convergence rate of an ANC system dealing with periodic disturbances. This algorithm consists in combining the organization of the filter weights in a hierarchy of subfilters of shorter length and their sequential partial updates (PU). Our contribution is threefold: (1) we provide the theoretical basis of the existence of a frequency-dependent parameter, called gain in step-size. (2) The theoretical upper bound of the step-size is compared with the limit obtained from simulations. (3) Additional experiments show that this strategy results in a fast algorithm with a computational complexity close to that of the conventional FxLMS.
Pedro Ramos Lorente; Raúl Martín Ferrer; Fernando Arranz Martínez; Guillermo Palacios-Navarro. Modified Filtered-X Hierarchical LMS Algorithm with Sequential Partial Updates for Active Noise Control. Applied Sciences 2020, 11, 344 .
AMA StylePedro Ramos Lorente, Raúl Martín Ferrer, Fernando Arranz Martínez, Guillermo Palacios-Navarro. Modified Filtered-X Hierarchical LMS Algorithm with Sequential Partial Updates for Active Noise Control. Applied Sciences. 2020; 11 (1):344.
Chicago/Turabian StylePedro Ramos Lorente; Raúl Martín Ferrer; Fernando Arranz Martínez; Guillermo Palacios-Navarro. 2020. "Modified Filtered-X Hierarchical LMS Algorithm with Sequential Partial Updates for Active Noise Control." Applied Sciences 11, no. 1: 344.
The location of large telescopes, generally far from the data processing centers, represents a logistical problem for the supervision of the capture of images. In this work, we carried out a preliminary study of the vibration signature of the T80 telescope at the Javalambre Astrophysical Observatory (JAO). The study analyzed the process of calculating the displacement that occurs because of the vibration in each of the frequencies in the range of interest. We analyzed the problems associated with very low frequencies by means of simulation, finding the most critical vibrations below 20 Hz, since they are the ones that generate greater displacements. The work also relates previous studies based on simulation with the real measurements of the vibration of the telescope taken remotely when it is subjected to different positioning movements (right ascension and/or declination) or when it performs movement actions such as those related to filter trays or mirror cover. The obtained results allow us to design a remote alarm system to detect invalid images (taken with excess vibration).
Fernando Arranz Martínez; Raúl Martín Ferrer; Guillermo Palacios-Navarro; Pedro Ramos Lorente. Study on the Vibration Characteristics of the Telescope T80 in the Javalambre Astrophysical Observatory (JAO) Aimed at Detecting Invalid Images. Sensors 2020, 20, 6523 .
AMA StyleFernando Arranz Martínez, Raúl Martín Ferrer, Guillermo Palacios-Navarro, Pedro Ramos Lorente. Study on the Vibration Characteristics of the Telescope T80 in the Javalambre Astrophysical Observatory (JAO) Aimed at Detecting Invalid Images. Sensors. 2020; 20 (22):6523.
Chicago/Turabian StyleFernando Arranz Martínez; Raúl Martín Ferrer; Guillermo Palacios-Navarro; Pedro Ramos Lorente. 2020. "Study on the Vibration Characteristics of the Telescope T80 in the Javalambre Astrophysical Observatory (JAO) Aimed at Detecting Invalid Images." Sensors 20, no. 22: 6523.
This work brings together the emerging virtual reality techniques and the natural user interfaces to offer new possibilities in the field of rehabilitation. We have designed a rehabilitation game based on a low cost device (Microsoft KinectTM) connected to a personal computer. It provides patients having Parkinson’s Disease (PD) with a motivating way to perform several motor rehabilitation exercises to improve their rehabilitation. The experiment was tested on seven Parkinson’s Disease patients and results demonstrated significant improvements in completion time score and in the 10 Meters Walk Test score. Nevertheless, additional research is needed to determine if this type of training has a long-term impact. Both the device and protocol were well accepted by subjects, being safe and easy to use. We conclude that our work provides a simple and suitable tool resulting in a more enriching rehabilitation process where motivation is highly encouraged in PD patients. Feedback coming from participants corroborate the hypothesis that the system can be applied not only in clinical rehabilitation centers but at home.
Guillermo Palacios-Navarro; Iván García-Magariño; Pedro Ramos-Lorente. A Kinect-Based System for Lower Limb Rehabilitation in Parkinson’s Disease Patients: a Pilot Study. Journal of Medical Systems 2015, 39, 1 .
AMA StyleGuillermo Palacios-Navarro, Iván García-Magariño, Pedro Ramos-Lorente. A Kinect-Based System for Lower Limb Rehabilitation in Parkinson’s Disease Patients: a Pilot Study. Journal of Medical Systems. 2015; 39 (9):1.
Chicago/Turabian StyleGuillermo Palacios-Navarro; Iván García-Magariño; Pedro Ramos-Lorente. 2015. "A Kinect-Based System for Lower Limb Rehabilitation in Parkinson’s Disease Patients: a Pilot Study." Journal of Medical Systems 39, no. 9: 1.
Pedro Ramos; Roberto Torrubia; Ana López; Ana Salinas; Enrique Masgrau. Step Size Bound of the Sequential Partial Update LMS Algorithm with Periodic Input Signals. EURASIP Journal on Audio, Speech, and Music Processing 2007, 2007, 1 -15.
AMA StylePedro Ramos, Roberto Torrubia, Ana López, Ana Salinas, Enrique Masgrau. Step Size Bound of the Sequential Partial Update LMS Algorithm with Periodic Input Signals. EURASIP Journal on Audio, Speech, and Music Processing. 2007; 2007 (1):1-15.
Chicago/Turabian StylePedro Ramos; Roberto Torrubia; Ana López; Ana Salinas; Enrique Masgrau. 2007. "Step Size Bound of the Sequential Partial Update LMS Algorithm with Periodic Input Signals." EURASIP Journal on Audio, Speech, and Music Processing 2007, no. 1: 1-15.