Examinando por Materia "Industria cementera"

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    Predicción del precio óptimo de compra de sacos de papel en la industria cementera : un enfoque basado en modelos SARIMAX, ARIMA y red neuronal LSTM
    (Universidad EAFIT, 2025-12-09) Morales Martínez, Andrés Felipe; Fonseca Valero, Diego Fernando
    This research addresses the problem of forecasting the purchase price of kraft paper sacks in the Colombian cement industry, within a context characterized by high price uncertainty and the absence of financial hedging instruments. Using internal transactional data extracted from the ERP system for the 2014–2023 period, together with public exogenous variables such as the exchange rate (TRM) and stock prices of global suppliers in the paper industry, a reproducible dataset was built for purchase price forecasting. The study compared the performance of four time-series approaches: ARIMA, SARIMAX, LSTM, and LightGBM, under a 90/10 temporal validation protocol and strict control of information leakage. As a central part of the methodology, a daily time series was reconstructed using the LOCF technique, and feature engineering was incorporated to better represent the stepwise nature of the price series. The results show that linear models and the LSTM applied to the original series produced high forecasting errors, whereas the best performance was achieved by nonlinear models applied to the transformed series. In particular, the LSTM with the transformed daily series achieved the best overall result (MAE = 4.57 COP), followed by LightGBM (MAE = 8.03 COP), clearly outperforming ARIMA and SARIMAX. It is concluded that an adequate representation of the time series is as important as the selection of the predictive model, and that the combination of internal data, exogenous variables, and nonlinear methods can generate useful operational signals to support more timely, objective, and data-driven purchasing decisions in industrial sourcing contexts.