A comprehensive model for power line interference in biopotential measurements

Power line interference is a major problem in high-resolution biopotential measurements. Because interference coupling is mostly capacitive, shielding electrode leads and a high common-mode rejection ratio (CMRR) are quite effective in reducing power-line interference but do not completely eliminate it. We propose a model that includes both interference external to the measuring system and interference coming from its internal power supply. Moreover, the model considers interference directly coupled to the measuring electrodes, because, as opposed to connecting leads, electrodes are not usually shielded. Experimental results confirm that reducing interference coupled through electrodes yields a negligible interference. The proposed model can be applied to other differential measurement systems, particulary those involving electrodes or sensors placed far apart.Peer Reviewe

RFID systems in medical environment: EMC issues

RFID is a promising technology in the healthcare area in order to improve patient safety and increase efficiency and reduce costs in the daily healthcare work. This paper analyzes the available literature regarding both interference of RFID systems in medical equipment and the interferences of medical equipment on RFID systems. The conclusion of this analysis is that is necessary to develop standards in order to protect medical equipment from RFID interferences, and standards to plan the deployment of RFID installations taking into account electromagnetic compatibility issues.Postprint (published version

Obtención de micropotenciales cardíacos latido a latido por vía superficial

Para la detección no invasiva de la señal del haz de his latido a latido, es necesario que el nivel de ruido e interferencias presentes en el registro sea extremadamente bajo. El estudio del entorno de medida donde se realizan los registros y la clasificación de las fuentes de ruido e interferencia, así como el estudio de su influencia en el registro, permite desarrollar técnicas de reducción de ruido e interferencias que facilitan la detección visual de dicha señal. Las técnicas de reducción de ruido e interferencias propuestas son: la relajación del paciente, la utilización de las derivaciones con la mayor relación señal a ruido, el uso de electrodos apantallados y activos, el apantallamiento del paciente mediante una tela conductora, el filtrado adaptativo y el promediado espacial de señal. La aplicación de estas técnicas ha permitido detectar de la señal de his en un porcentaje elevado de los casos estudiados. La señal detectada en la superficie del cuerpo no puede competir con las obtenidas mediante registros intracavitarios, debido a su menor amplitud y a que no se consigue la detección en el 100% de los casos. No obstante, el bajo coste del equipo diseñado y la simplicidad de las técnicas de procesado de señal aplicadas hacen que la detección superficial de la señal pueda ser valida como una prueba diagnostica extrahospitalaria

RFID system evaluation against radiated transient noise

In this paper a radiofrequency identification system according to standard ISO/IEC 14443 type-B is evaluated in presence of transient noise. This real time communication system working at 13.56 MHz is interfered in a controlled environment by different transient bursts varying their level, frequency and duration. The transient burst interference is applied in an AC main wire close to the system and the effect over the digital communication system is evaluated using two different methods. The first one is observing directly an RFID equipment in presence of transient signals, and the second one is capturing the interference in time domain an evaluating its effect by means of simulation. The RFID system is affected by these transient noises causing different types of errors. It is shown that it is essential to measure and evaluate in time domain the transient phenomena to ensure that the RFID system do not have susceptibility problems.Peer ReviewedPostprint (published version

Understanding electrosurgical unit perturbations in order to address hospital operating room electromagnetic compatibility

We analyze the radiated emissions from a low power electrosurgical unit (ESU). Measurements at a 3-meter distance are performed in order to find a suitable measurement setup intended to reproduce realistically the real working ESU behavior in a test lab. The broad-band and narrow-band characteristics of the perturbation are studied in order to address the other equipment immunity.Peer Reviewe

Driver drowsiness detection based on respiratory signal analysis

Drowsy driving is a prevalent and serious public health issue that deserves attention. Recent studies estimate around 20% of car crashes have been caused by drowsy drivers. Nowadays, one of the main goals in the development of new advanced driver assistance systems is the trustworthy drowsiness detection. In this paper, a drowsiness detection method based on changes in the respiratory signal is proposed. The respiratory signal, which has been obtained using an inductive plethysmography belt, has been processed in real-time in order to classify the driver’s state of alertness as drowsy or awake. The proposed algorithm is based on the analysis of the respiratory rate variability (RRV) in order to detect the fight against to fall asleep. Moreover, a method to provide a quality level of the respiratory signal is also proposed. Both methods have been combined to reduce false alarms due to changes of measured RRV associated not to drowsiness but body movements. A driving simulator cabin has been used to perform the validation tests and external observers have rated the drivers’ state of alertness in order to evaluate the algorithm performance. It has been achieved a specificity of 96.6%, sensitivity of 90.3% and Cohen’s Kappa agreement score of 0.75 on average across all subjects through a leave-one-subject-out cross-validation. A novel algorithm for driver’s state of alertness monitoring through the identification of the fight against to fall asleep has been validated. The proposed algorithm may be a valuable vehicle safety system to alert drowsiness while drivingPeer ReviewedPostprint (published version

Bases metodológicas para el uso de tecnología bim como herramienta de simulación energética en rehabilitación

La presente comunicación parte de una línea de investigación iniciada en el departamento de Expresión Gráfica e Ingeniería en la Edificación de la Escuela Técnica Superior de Ingeniería de la Edificación de la Universidad de Sevilla, que pretende implementar el uso de los modelos BIM dentro del campo de la rehabilitación energética. El objetivo de la investigación será desarrollar el uso de nuevas tecnologías de diseño BIM (Building Information Modeling) como herramienta de simulación tendente a la mejora energética de edificios existentes y arquitectura patrimonial a rehabilitar, mediante la construcción de modelos virtuales para el estudio integral y simulación de eficiencia energética de los mismos. Dicho modelo permitirá integrar el propio desarrollo de proyecto con la simulación energética, de forma que decisiones de proyecto puedan irse ensayando de manera simultanea y conocer así la incidencia energética de las diferentes soluciones planteadas. Para ello planteamos la metodología de trabajo que a continuación se resume y que se desarrollara a continuación: 1. Visita y toma de datos inicial del edificio, con el objetivo de construir una maqueta virtual sobre la que trabajar en la plataforma BIM. 2. Simulación inicial para conocer la situación energética de partida del edificio. 3. Propuesta de mejoras a llevar a cabo en la edificación (desarrollo del proyecto de rehabilitación energética). 4. Simulación energética del modelo basado en tecnología BIM de manera simultánea al desarrollo del proyecto, para conocer la incidencia y mejora que cada una de las soluciones planteadas aporta. 5. Obtención de la certificación energética final del edificio rehabilitado. A partir de este análisis los resultados esperados fruto de la investigación realizada serán: 1. Creación de un protocolo de auditoría energética específico para la rehabilitación de edificación existente, mediante la utilización de herramientas BIM. 2. Generación de un patrón de comportamiento energético de las diferentes soluciones ensayadas, de forma que pueda estimarse la incidencia en el ahorro energético global del edificio de cada una de las acciones propuestas, y a partir de éste el ahorro económico de cada una de ellas a medio y largo plazo

A new and fast index for the quantification of short range self-similarity in RR time series

We propose a new and very fast index (the frequency of sign changes of the mirrored differences or fscmd) with good correlation with the short range scaling exponent ( Ｒ) estimated among scales 4 to 16 of the DFA. fscmd computes the relative number of sign changes of the difference of the RR time series minus their corresponding reversed RR time series after a moving average detrending procedure is applied using a window of 30 samples. Linear regression results with simulated time series with Fractional Brownian Noise and with actual time series using the Fantasia (FT), Normal Sinus Rhythm RR time series (NSR) and Congestive Heart Failure RR interval (CHF) databases after artifact correction show good agreement between fscmd and Ｒ. Finally, Mann-Whitney Rank Sum tests applied to Ｒ and fscmd when comparing NSR and CHF databases show very significant differences (p<0.001) between groups for both indices.Postprint (published version

Arousal detection by using ultra-short-term heart rate variability (HRV) analysis

Introduction: The study of arousal is crucial as it helps to understand the role of increased physiological and psychological activation in emotions, motivation, cognitive performance, stress responses, sleep-wake cycles, and clinical application. Recent studies have shown that arousal is commonly associated with physiological changes including heart rate variability (HRV) as indicated by RR intervals. In some applications, the analysis requires analyzing short segments of RR time series, shorter than the usual 5 min HRV. The objective of this study is to check the performance of ultra-short-term HRV indices to track changes in arousal. Method: In this study, to follow arousal changes, 31 healthy subjects were examined in both non-arousal (relaxed) and aroused states. Two states of 5 minutes each are used to measure the relaxed and arousal states. After data collection, RR time series segments were obtained randomly for each subject in arousal and relaxed states in the 30s, 60s, 120s, and 240s time windows. Next, 17 ultra-short-term HRV indices were computed for each time window for RR intervals in relaxed and aroused states.Postprint (published version

Transient perturbation analysis in digital radio

This paper presents a new simulation methodology to study the effect of radiated transient disturbances on digital communication systems. The procedure is divided in two stages. In the first one, FDTD numerical simulation is used to determine the transient levels coupled to the antennas. In the second stage, these levels are analyzed by means of a signal processing simulation software to determine the degradation caused in the system. The procedure is applied to a DAB system in car when a radiated interference is generated by a transient in a vehicle cable. The results show that the amplitude of the radiated transient coupled signal is a key parameter, but it is also essential to take into account other parameters such as burst duration and frequency.Postprint (published version