Chemometric Analysis of a Ternary Mixture of Caffeine, Quinic Acid, and Nicotinic Acid by Terahertz Spectroscopy

Caffeine, quinic acid, and nicotinic acid are among the significant chemical determinants of coffee quality. This study develops a chemometric model to quantify these compounds in ternary mixtures analyzed by terahertz time-domain spectroscopy (THz-TDS). A data set of 480 THz spectra was obtained from 80 samples. Combinations of data preprocessing methods, including normalization (Z-score, min-max scaling, Mie baseline removal) and dimensionality reduction (principal component analysis (PCA), factor analysis (FA), independent component analysis (ICA), locally linear embedding (LLE), non-negative matrix factorization (NMF), isomap), and prediction models (partial least-squares regression (PLSR), support vector regression (SVR), multilayer perceptron (MLP), convolutional neural network (CNN), gradient boosting) were analyzed for their prediction performance (totaling to 4,711,685 combinations). Results show that the highest quantification performance was achieved at a root-mean-square error of prediction (RMSEP) of 0.0254 (dimensionless mass ratio), using min-max scaling and factor analysis for data preprocessing and multilayer perceptron for prediction. Effects of preprocessing, comparison of prediction models, and linearity of data are discussed

Knowledge Management on Asset Management for End of Life Products

Part 8: Knowledge Creation and ManagementInternational audienceBecause of considerable high labor cost in developed countries particularly Japan and Korea, the end of life products required manual or semi-manual processes have been relocated to developing countries. In addition, the relocation creates an immediate financial profit on old asset sale while it is revalued to 30 % of its initial value in the new relocated factory. The relocation is not only production location change but also the experience in operation and maintenance process to its Foreign Direct Investment affiliate. Since the old product and process are both nearly at their end of life, it needs to extend the life as long as the product still exists in the market. In order to immediately launch the operation as well as to retain the knowledge, therefore, the asset management and new maintenance modes are proposed at all product, process and people aspects to improve reliability of the old asset and to minimize maintenance cost. The research in this paper was carried out on a Korean relocated electronic factory in Thailand. The result clearly shows that the reliability, quality, cost and intellectual capital are significantly improved