Clustering Techniques Selection for a Hybrid Regression Model: A Case Study Based on a Solar Thermal System

[EN] This work addresses the performance comparison between four clustering techniques with the objective of achieving strong hybrid models in supervised learning tasks. A real dataset from a bio-climatic house named Sotavento placed on experimental wind farm and located in Xermade (Lugo) in Galicia (Spain) has been collected. Authors have chosen the thermal solar generation system in order to study how works applying several cluster methods followed by a regression technique to predict the output temperature of the system. With the objective of defining the quality of each clustering method two possible solutions have been implemented. The first one is based on three unsupervised learning metrics (Silhouette, Calinski-Harabasz and Davies-Bouldin) while the second one, employs the most common error measurements for a regression algorithm such as Multi Layer Perceptron.S

Avionic air data sensors fault detection and isolation by means of singular perturbation and geometric approach

Singular Perturbations represent an advantageous theory to deal with systems characterized by a two-time scale separation, such as the longitudinal dynamics of aircraft which are called phugoid and short period. In this work, the combination of the NonLinear Geometric Approach and the Singular Perturbations leads to an innovative Fault Detection and Isolation system dedicated to the isolation of faults affecting the air data system of a general aviation aircraft. The isolation capabilities, obtained by means of the approach proposed in this work, allow for the solution of a fault isolation problem otherwise not solvable by means of standard geometric techniques. Extensive Monte-Carlo simulations, exploiting a high fidelity aircraft simulator, show the effectiveness of the proposed Fault Detection and Isolation system.Singular Perturbations represent an advantageous theory to deal with systems characterized by a two-time scale separation, such as the longitudinal dynamics of aircraft which are called phugoid and short period. In this work, the combination of the NonLinear Geometric Approach and the Singular Perturbations leads to an innovative Fault Detection and Isolation system dedicated to the isolation of faults affecting the air data system of a general aviation aircraft. The isolation capabilities, obtained by means of the approach proposed in this work, allow for the solution of a fault isolation problem otherwise not solvable by means of standard geometric techniques. Extensive Monte-Carlo simulations, exploiting a high fidelity aircraft simulator, show the effectiveness of the proposed Fault Detection and Isolation system

Hybrid Intelligent System to Perform Fault Detection on BIS Sensor During Surgeries

This paper presents a new fault detection system in hypnotic sensors used for general anesthesia during surgery. Drug infusion during surgery is based on information received from patient monitoring devices; accordingly, faults in sensor devices can put patient safety at risk. Our research offers a solution to cope with these undesirable scenarios. We focus on the anesthesia process using intravenous propofol as the hypnotic drug and employing a Bispectral Index (BISTM) monitor to estimate the patient’s unconsciousness level. The method developed identifies BIS episodes affected by disturbances during surgery with null clinical value. Thus, the clinician—or the automatic controller—will not take those measures into account to calculate the drug dose. Our method compares the measured BIS signal with expected behavior predicted by the propofol dose provider and the electromyogram (EMG) signal. For the prediction of the BIS signal, a model based on a hybrid intelligent system architecture has been created. The model uses clustering combined with regression techniques. To validate its accuracy, a dataset taken during surgeries with general anesthesia was used. The proposed fault detection method for BIS sensor measures has also been verified using data from real cases. The obtained results prove the method’s effectiveness

Modelado de sistemas complejos mediante métodos de agrupamiento e hibridación de técnicas inteligentes

El presente trabajo de investigación aborda el estudio y desarrollo de un sistema de modelado híbrido que combina métodos de agrupamiento estándar, o clustering, con algoritmos de regresión. Con esta propuesta, se pretende dividir el problema de modelado de un sistema en un conjunto de modelos locales. De esta forma se pueden definir zonas con un comportamiento similar de un modo más preciso. Durante la etapa de regresión, se aplican varias técnicas sobre cada uno de los grupos, con el fin de lograr la mejor aproximación en los modelos locales obtenidos. Por tanto, el modelo híbrido estará formado por el conjunto de todos estos modelos. Esta novedosa propuesta permite obtener resultados altamente satisfactorios en todos los procesos reales en los que se ha aplicado. El sistema desarrollado ha sido validado sobre tres supuestos reales diferentes. En el primero de ellos, el modelo híbrido se emplea para obtener o predecir el valor que debiera medir un sensor para poder realizar detección de fallos. La aplicación real utiliza la señal BIS, que se emplea para determinar el grado de hipnosis de un paciente sedado. En el segundo, el modelo propuesto se utiliza para crear un sensor virtual, obteniendo el valor de una variable a partir de otras. La aplicación real, en este caso, se desarrolla sobre un sensor para monitorizar el estado de carga de una batería. En el último caso, el modelo híbrido se usa para predecir valores de variables en un tiempo futuro, en instantes posteriores al de la ejecución del modelo. Como aplicación real para este caso, se trata de predecir el valor de la señal ANI empleada en operaciones quirúrgicas, que es un indicador del dolor que sufren los pacientes durante una intervención

Automation of the anesthetic process: New computer-based solutions to deal with the current frontiers in the assessment, modeling and control of anesthesia

The current trend in automating the anesthetic process focuses on developing a system for fully controlling the different variables involved in anesthesia. To this end, several challenges need to be addressed first. The main objective of this thesis is to propose new solutions that provide answers to the current problems in the field of assessing, modeling and controlling the anesthetic process. Undoubtedly, the main handicap to the development of a comprehensive proposal lies in the absence of a reliable measure of analgesia. This thesis proposes a novel fuzzy-logic-based scheme to evaluate the impact of including a new variable in a decision-making process. This scheme is validated by way of a preliminary analysis of the Analgesia Nociception Index (ANI) monitor on analgesic drug titration. Furthermore, the capacity of the ANI monitor to provide information to replicate the decisions of the experts in different clinical situations is studied. To this end, different artificial intelligence-based algorithms are used: specifically, the suitability of this index is evaluated against other variables commonly used in clinical practice. Regarding the modeling of anesthesia, this thesis presents an adaptive model that allows characterizing the pharmacological interaction effects between the hypnotic and analgesic drug on the depth of hypnosis. In addition, the proposed model takes into account both inter- and intra-patient variabilities observed in the response of the subjects. Finally, this work presents the synthesis of a robust optimal PID controller for regulating the depth of hypnosis by considering the effect of the uncertainties derived from the patient's pharmacological response. Moreover, a study is conducted on the limitations introduced when using a PID controller versus the development of higher order solutions under the same clinical and technical considerations