Forecasting Electricity Demand for Small Colombian Populations.

Pronóstico de la demanda de electricidad para pequeñas poblaciones colombianas.AbstractThe socioeconomic and cultural behavior of a population may be reflected in the consumption of electrical energy. Due to the foregoing, researchers and academics have developed models to predict electricity demand in the short, medium and long term. This paper presents an Artificial Neural Network (ANN) for the prediction of daily electricity demand (GWh) in small Colombian populations. The methodology proposed by Kaastra and Boyd is used for the construction, training and validation of the network and the development of the model in the statistical software SPSS. This paper conclude that the predicted values with models constructed with Artificial Neural Networks (ANN) present a greater degree of approach with the real values of electricity demand (GWh). Also it indicates that the values obtained using models developed with other forecasting techniques (game theory, time series, simulation models, and others) allow to include variables and external factors that are difficult to quantify with simple equations.Keywords: Electricity demand, forecasting models, multi-layer perceptron, artificial neural networks, seasonal time series.Resumen El comportamiento socio económico y cultural de una población puede verse reflejado en el consumo de energía eléctrica. Debido a lo anterior, investigadores y académicos han desarrollado modelos que permitan pronosticar la demanda de la misma en el corto, mediano y largo plazo. Este trabajo presenta una red neuronal artificial (RNA) para el pronóstico de la demanda diaria de electricidad (GWh) en pequeñas poblaciones colombianas. Para la construcción, entrenamiento y validación de la red se empleó la metodología propuesta por Kaastra y Boyd en el software estadístico SPSS. Con el desarrollo de este trabajo se concluye que  los valores pronosticados con modelos construidos con redes neuronales artificiales (RNA), presentan un mayor grado de acercamiento a los valores reales de la demanda de electricidad (GWh), que los valores obtenidos con modelos desarrollados con otras técnicas de pronóstico (teoría de juegos, series de tiempo, modelos de simulación, entre otros), ya que permiten incluir variables y factores externos que son difíciles de cuantificar por medio de simples ecuaciones. Palabras clave: Demanda de electricidad, modelo de pronóstico, perceptron multicapa, redes neuronales artificiales, series de tiempo estacionales

Exports and imports in Zimbabwe: recent insights from artificial neural networks

This study, which is the first of its kind in the case of Zimbabwe; attempts to model and forecast Zimbabwe’s exports and imports using annual time series data ranging over the period 1975 – 2017. In order to analyze Zimbabwe’s export and import dynamics, the study employed the Neural Network approach, a deep-learning technique which has not been applied in this area in the case of Zimbabwe. The Hyperbolic Tangent function was selected and applied as the activation function of the neural networks applied in this study. The neural networks applied in this research were evaluated using the most common forecast evaluation statistics, i.e. the Error, MSE and MAE; and it was clearly shown that the neural networks yielded reliable forecasts of Zimbabwe’s exports and imports over the period 2018 – 2027. The main results of the study indicate that imports will continue to outperform exports over the out-of-sample period. Amongst other policy recommendations, the study encourages Zimbabwean policy makers to intensify export growth promotion policies and strategies such as clearly identifying export drivers as well as export diversification if persistant current account deficits in Zimbabwe are to be dealt with effectively

Exports and imports in Zimbabwe: recent insights from artificial neural networks

This study, which is the first of its kind in the case of Zimbabwe; attempts to model and forecast Zimbabwe’s exports and imports using annual time series data ranging over the period 1975 – 2017. In order to analyze Zimbabwe’s export and import dynamics, the study employed the Neural Network approach, a deep-learning technique which has not been applied in this area in the case of Zimbabwe. The Hyperbolic Tangent function was selected and applied as the activation function of the neural networks applied in this study. The neural networks applied in this research were evaluated using the most common forecast evaluation statistics, i.e. the Error, MSE and MAE; and it was clearly shown that the neural networks yielded reliable forecasts of Zimbabwe’s exports and imports over the period 2018 – 2027. The main results of the study indicate that imports will continue to outperform exports over the out-of-sample period. Amongst other policy recommendations, the study encourages Zimbabwean policy makers to intensify export growth promotion policies and strategies such as clearly identifying export drivers as well as export diversification if persistant current account deficits in Zimbabwe are to be dealt with effectively

Temperature-Driven Anomaly Detection Methods for Structural Health Monitoring

Reported in this thesis is a data-driven anomaly detection method for structural health monitoring which is based on the utilization of temperature-induced variations. Structural anomaly detection should be able to identify meaningful changes in measurements which are due to structural abnormal behaviour. Because, the temperature-induced variations and structural abnormalities may produce significant misinterpretations, the development of solutions to identify a structural anomaly, accounting for temperature influence, from measurements, is a critical procedure to support structural maintenance. A temperature-driven anomaly detection method is proposed, that introduces the idea of blind source separation for extracting thermal response and for further anomaly detection. Two thermal feature extraction methods are employed corresponding to the classification of underdetermined and overdetermined methods. The underdetermined method has the three phases of: (a) mode decomposition by utilising Empirical Mode Decomposition or Ensemble Empirical Mode Decomposition; (b) data reduction by performing Principal Component Analysis (PCA); (c) blind separation by applying Independent Component Analysis (ICA). The overdetermined method has the two stages of the pre-indication according to PCA and the blind separation by the devotion of ICA. Based on the extracted thermal response, the temperature-driven anomaly detection method is later developed in combination with the four methodologies of: Moving Principal Component Analysis (MPCA); Robust Regression Analysis (RRA); One-Class Support Vector Machine (OCSVM); Artificial Neural Network (ANN). Therefore, the proposed temperature-driven anomaly detection methods are designed as Td-MPCA, Td-RRA, Td-OCSVM, and Td-ANN. The proposed thermal feature extraction methods and temperature-driven anomaly detection methods have been investigated in the context of three case studies. The first case is a numerical truss bridge with simulated material stiffness reduction to create levels of damage. The second case is a purpose constructed truss bridge in the Structures Lab at the University of Warwick. The third case study is Ricciolo curved viaduct in Switzerland. Two primary findings can be confirmed from the evaluation results of these three case studies. Firstly, temperature-induced variations can conceal damage information in measurements. Secondly, the detection abilities of temperature-driven methods, which are Td-MPCA, Td-RRA, Td-OCSVM, and Td-ANN, for disclosing slight anomalies in time are more efficient when compared with the current anomaly detection method, which are MPCA, RRA, OCSVM, and ANN. The unique features of the author’s proposed temperature-driven anomaly detection method can be highlighted as follows: (a) it is a data-driven method for extracting features from an unknown structural system. In another word, the prior knowledge of the structural in-service conditions and physical models are not necessary; (b) it is the first time that blind source separation approaches and relative algorithms have been successfully employed for extracting temperature-induced responses; (c) it is a new approach to reliably assess the capability of using temperature-induced responses for anomaly detection

Computational issues in process optimisation using historical data.

This thesis presents a new generic approach to improve the computational efficiency of neural-network-training algorithms and investigates the applicability of its 'learning from examples'' featured in improving the performance of a current intelligent diagnostic system. The contribution of this thesis is summarised in the following two points: For the first time in the literature, it has been shown that significant improvements in the computational efficiency of neural-network algorithms can be achieved using the proposed methodology based on using adaptive-gain variation. The capabilities of the current Knowledge Hyper-surface method (Meghana R. Ransing, 2002) are enhanced to overcome its existing limitations in modelling an exponential increase in the shape of the hyper-surface. Neural-network techniques, particularly back-propagation algorithms, have been widely used as a tool for discovering a mapping function between a known set of input and output examples. Neural networks learn from the known example set by adjusting its internal parameters, referred to as weights, using an optimisation procedure based on the 'least square fit principle'. The optimisation procedure normally involves thousands of iterations to converge to an acceptable solution. Hence, improving the computational efficiency of a neural-network algorithm is an active area of research. Various options for improving the computational efficiency of neural networks have been reviewed in this thesis. It has been shown in the existing literature that the variation of the gain parameter improves the learning efficiency of the gradient-descent method. However, it can be concluded from previous researchers' claims that the adaptive-gain variation improved the learning rate and hence the efficiency. It was discovered in this thesis that the gain variation has no influence on the learning rate; however, it actually influences the search direction. This made it possible to develop a novel approach that modifies the gradient-search direction by introducing the adaptive-gain variation. The proposed method is robust and has been shown that it can easily be implemented in all commonly used gradient- based optimisation algorithms. It has also been shown that it significantly improves the computational efficiency as compared to existing neural-network training algorithms. Computer simulations on a number of benchmark problems are used throughout to illustrate the improvement proposed in this thesis. In a foundry a large amount of data is generated within the foundry every time a casting is poured. Furthermore, with the increased number of computing tools and power there is a need to develop an efficient, intelligent diagnostic tool that can learn from the historical data to gain further insight into cause and effect relationships. In this study the performance of the current Knowledge Hyper-surface method was reviewed and the mathematical formulation of the current Knowledge Hyper-surface method was analysed to identify its limitations. An enhancement is proposed by introducing mid-points in the existing shape formulation. It is shown that the midpoints' shape function can successfully constrain the shape of decision hyper-surface to become more realistic with an acceptable result in a multi-dimensional case. This is a novel and original approach and is of direct relevance to the foundry industry