Investigation of chemo-mechanical actuation in polymer gels

The objective of this thesis is to investigate chemically – driven gel actuators and their usefulness to perform mechanical work. The thesis work has mainly concentrated on chitosan as the gel actuator material. Chitosan is a widely used biopolymer that shows a large volume transition through changing pH. The pH induced actuation behaviour of polymer gels makes these materials analogous to a biological muscle. From a mechanics viewpoint, polymers gels are very compliant, unlike more common engineering material such as metals or ceramics or even most polymers. The mechanical work output of an actuation system is determined from a combination of the displacement and force generated. A complication arises with gel actuators since prior work has shown that the application of an external force can change the gel volume transition. Very little information is available regarding the specific effect of an external load on the displacement generated by a gel actuator. The thesis included experiments on a homogeneous solvent swollen rubber as a model system. Actuation of the rubber was effected through solvent exchange. The mechanical actuation was investigated by three different approaches: Linear Elastic, Thermodynamic and Linear Elastic generalized to 3D (finite element model). These models are to account for both the mechanical properties and the actuation behaviour of these materials. Uniaxial mechanical testing has been conducted on natural rubber and chitosan gel in both the fully expanded and fully contracted states, and the material parameters from these mechanical tests were used in the various models. The model and material parameters are then used to predict the rubber/chitosan actuation behaviour under isotonic loading. Actuation tests on chitosan fibres showed unexpected results. Chitosan fibres showed a considerable strain difference between length and diameter during free actuation. An applied load during actuation process gave completely unexpected results: contraction in the length direction when expansion was expected and vice versa. The 3 - dimensional elastic approach based on the Finite Element Model was modified from the isotropic material (natural rubber) to account for the anisotropic chitosan fibres. This model enables a reasonable estimate of the Young’s modulus and Poisson’s ratio. The results suggest that the materials have different Young’s modulus in the longitudinal and transversal directions which produces a high expansion in the transversal direction in comparison with the longitudinal, affecting directly the actuation process. Moreover the changes in Poisson’s ratio and modulus due to a change in the chemical environment (pH or solvent) were also shown to account for the unexpected actuation results. Useful dynamic information on the molecular scale was obtained on the structure of the fibre using a real-time small angle X-ray scattering (SAXS) technique. Parameters (particularly correlation lengths and intensity) fitted to the experimental data clearly indicated structural differences in the directions perpendicular and parallel to the fibre axis, however detailed description of the molecular organisation requires further investigation

Motion Detection by Microcontroller for Panning Cameras

Motion detection is the first essential process in the extraction of information regarding moving objects. The approaches based on background difference are the most used with fixed cameras to perform motion detection, because of the high quality of the achieved segmentation. However, real time requirements and high costs prevent most of the algorithms proposed in literature to exploit the background difference with panning cameras in real world applications. This paper presents a new algorithm to detect moving objects within a scene acquired by panning cameras. The algorithm for motion detection is implemented on a Raspberry Pi microcontroller, which enables the design and implementation of a low-cost monitoring system.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Deep learning-based anomalous object detection system powered by microcontroller for PTZ cameras

Automatic video surveillance systems are usually designed to detect anomalous objects being present in a scene or behaving dangerously. In order to perform adequately, they must incorporate models able to achieve accurate pattern recognition in an image, and deep learning neural networks excel at this task. However, exhaustive scan of the full image results in multiple image blocks or windows to analyze, which could make the time performance of the system very poor when implemented on low cost devices. This paper presents a system which attempts to detect abnormal moving objects within an area covered by a PTZ camera while it is panning. The decision about the block of the image to analyze is based on a mixture distribution composed of two components: a uniform probability distribution, which represents a blind random selection, and a mixture of Gaussian probability distributions. Gaussian distributions represent windows in the image where anomalous objects were detected previously and contribute to generate the next window to analyze close to those windows of interest. The system is implemented on a Raspberry Pi microcontroller-based board, which enables the design and implementation of a low-cost monitoring system that is able to perform image processing.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Relaciones entre la práctica física, condición física y atención en una muestra adolescente

El propósito de este trabajo fue examinar las relaciones entre la práctica de actividad física, la condición física y la atención en un grupo de adolescentes. Participaron en el estudio 149 adolescentes de la provincia de Málaga (España), con edades entre 14 y 16 años (M = 15.05; DE = .77). Para analizar los procesos atencionales se utilizó el test d2. La condición física se evaluó a través del test de salto horizontal, el test de Course Navette y el test de velocidad 5 x 10 metros. Los análisis indicaron mayores puntuaciones en diversos parámetros del test d2 en aquellos participantes que realizaban actividad física regularmente, así como relaciones significativas entre las medidas de condición física y las pruebas de atención, siendo el consumo de oxígeno la variable más relevante. Los resultados hallados apoyan la importancia de practicar actividad física en la infancia y la adolescencia, sugiriendo que el incremento de la condición física puede tener implicaciones positiva sobre la atención en estas edades.The purpose of this study was to examine the relationship between physical activity, fitness and attention in a group of adolescents. 149 adolescents aged between 14 and 16 years old (M = 15.05; SD = .77) took part in the study. The D-2 Test was used to analyse attention processes. Physical fitness was assessed with the horizontal jump test, the Course Navette test and the 5 x 10 metre sprint test. Analyses indicated higher scores on some measures of the D-2 test in participants who regularly did sports and significant relationships between fitness tests and measurements of attention, with oxygen consumption being the most relevant variable. The results obtained support the importance of physical activity in childhood and adolescence, suggesting that increased fitness may have positive implications on attention at this age.O propósito deste trabalho foi analisar as relações entre a prática de actividade física, a condição física e a atenção num grupo de adolescentes. Participaram no estudo 149 adolescentes da província de Málaga (Espanha), com idades compreendidas entre os 14 e os 16 anos (M = 15.05; DP = .77). Para analisar os processos atencionais foi utilizado o teste d2. A condição física foi avaliada através do teste de salto horizontal, o teste de Course Navette e o teste de velocidade 5 x 10 metros. As análises indicaram pontuações mais elevadas nos diversos parâmetros do teste d2 para os participantes que realizavam actividade física regularmente, assim como relações significativas entre as medidas de condição física e as provas de atenção, sendo o consumo de oxigénio a variável mais relevante. Os resultados encontrados suportam a importância de praticar actividade física na infância e adolescência, sugerindo que o incremento da condição física pode ter implicações positivas na atenção nestas idades

Unit commitment with analytical underfrequency load-shedding constraints for island power systems

This letter presents a corrective frequency-constrained UC (C-FCUC) for island power systems implementing analytical constraints on underfrequency load shedding (UFLS). Since UFLS is inevitable for sufficiently large disturbances, one can argue that less spinning reserve could be held back since UFLS takes place anyway. Congruently, the reserve criterion should consider UFLS likely to occur under disturbances. The C-FCUC can be converted into a preventive frequency-constrained UC (P-FCUC) or the standard unit commitment (UC) and the C-FCUC is thus a generalization. The proposed formulation is successfully applied to a Spanish island power system

Data-driven Estimation of Under Frequency Load Shedding after Outages in Small Power Systems

This paper presents a data-driven methodology for estimating Under Frequency Load Shedding (UFLS) in small power systems. UFLS plays a vital role in maintaining system stability by shedding load when the frequency drops below a specified threshold following loss of generation. Using a dynamic System Frequency Response (SFR) model we generate different values of UFLS (i.e., labels) predicated on a set of carefully selected operating conditions (i.e., features). Machine Learning (ML) algorithms are then applied to learn the relationship between chosen features and the UFLS labels. A novel regression tree and the Tobit model are suggested for this purpose and we show how the resulting non-linear model can be directly incorporated into a Mixed Integer Linear Programming (MILP) problem. The trained model can be used to estimate UFLS in security-constrained operational planning problems, improving frequency response, optimizing reserve allocation, and reducing costs. The methodology is applied to the La Palma island power system, demonstrating its accuracy and effectiveness. The results confirm that the amount of UFLS can be estimated with the Mean Absolute Error (MAE) as small as 0.213 MW for the whole process, with a model that is representable as a MILP for use in scheduling problems such as unit commitment among others

Cataloga diferente

Se explica cómo se realiza la catalogación en la Biblioteca de la Universidad de Cádiz. Se comienza el proceso con la importación de ficheros con registros MARC21 a Koha que posteriormente se normalizan. Se describen dos formas de tratar los registros dependiendo de los Campus; desde el Campus de Cádiz, las cargas de registros se hacen en el Servicio Central y a través de informes SQL guardados en el sistema se hace una catalogación “virtual” sin libros en mano. En los restantes Campus (Jerez, Puerto Real y Algeciras) se cargan los ficheros y con los libros físicos se catalogan y normalizan. También destacamos dos funcionalidades de Koha: cómo asociar al registro bibliográfico (música o vídeos) con enlaces externos; y la inclusión de cubiertas asociadas al ISBN