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5.5 Conclusion In order to verify the generalisation ability of the implemented multivariate analysis pipeline, the constructed statistical tools were tested upon three new individual real-world case studies featuring different types of data (beef fillets, minced beef, pork), which have been analysed using a variety of instruments (FTIR, HPLC, Raman and e-nose) under different temperatures and packaging. By analysing the new case studies, we were able to show that significant results can be obtained on further datasets. In addition, by a direct comparison of their results, some noteworthy conclusions were drawn. HPLC proved to be the best instrumental technique for the chosen application of assessing meat freshness. Standalone HPLC data, both prior and after the application of PCA, consistently demonstrated the highest percentages of correctly classified samples (%CC). Thus, we can conclude that the provided HPLC data contained abundances of several specific chemical compounds associated with and denoting spoilage. Conversely, the FTIR, Raman and e-nose data were the measurements of raw sensors with no prior feature selection or mapping to specific compounds. Also, it is obvious that the HPLC data present higher classification accuracies for kernelbased (RBF) SVMs. On the contrary, the overall accuracies of the simple spectroscopic data by FTIR are clearly profiting by the application of linear classifiers, and especially by the application of traditional chemometric methods such as PLS-DA. In this instance, the nonlinear mapping by RBF SVMs has been found unfit. Finally, the e-nose data did not demonstrate any discriminative information, and its classification results proved to be statistically non-significant. As far as the integrated datasets are concerned, CPCA was consistently found to be a better data fusion technique than GPA. More specifically, CPCA clearly improves the outcome of the integration by combining the strongest features of the initial datasets, while GPA appears to be dominated by the weakest experimental technique. 169
6 Development of improved visualisation methods for chemometrics applications 6.1 Introduction A range of novel visualisation tools has been used throughout this thesis. This chapter provides a thorough description of the visualisation techniques, graphics libraries and web technologies underlying these tools. Even though there has been tremendous progress in the field of chemometrics, often the visualisation tools used to demonstrate the results are out-dated and the graphs occasionally difficult to comprehend. One of the aims of this project was to pursue the development of new visualisation methods that enhance the interpretability of the project’s data and results, with a view to employing them for the construction of static images, interactive web-based graphs, and dynamically generated reports. 6.2 Materials and Methods 6.2.1 The importance of Data Visualisation Data visualisation can be defined as “the science of visual representation of data, which contains information abstracted in some schematic form, including attributes or variables for the units information” (Friendly, 2001). Over the past years, software systems have attempted to integrate heterogeneous data at both the data source and the semantic level (Goesmann et al., 2003). However, the sheer volume and complexity of the data under study makes it almost impossible to illustrate using traditional visualisation methods. 170
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CRANFIELD UNIVERSITY Eleni Anthippi
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ABSTRACT Muscle foods such as meat,
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TABLE OF CONTENTS ABSTRACT ........
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6.2.4 The iWebPlots package .......
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Figure 3-12 Speedup produced by the
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Figure 6-9 Sweave example for the d
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TABLE OF EQUATIONS Equation 1 Mean-
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RMSE RMSECV SSE SVD SVMs SYMBIOSIS-
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Figure 1-1 Evolution from molecular
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1.1.2.1 Fourier Transform Infrared
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1.1.3 Microbial Spoilage in Meat Sy
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The multivariate techniques applied
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1.4 Multivariate Analysis: Unsuperv
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1.4.2 Cluster Analysis Cluster anal
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1.5 Multivariate Analysis: Supervis
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In any linearly separable binary da
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Where ( ) are the Lagrange multipli
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Every kernel is characterised by a
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The “one-against-all” approach
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Furthermore, metrics such as the bi
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1.6.3 Leave-One-Out Cross-Validatio
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In such cases, the model becomes qu
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1.8 Aims and objectives The overall
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2 Development of the multivariate a
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Sensory panel scores were of the hi
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DF (Hz) 2.2.1.5 Electronic Nose (e-
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Figure 2-3 Data intersection The fi
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3. Validation Techniques In the cas
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Figure 2-4 The process of construct
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2.3 Results and Discussion 2.3.1 Pr
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(b) HPLC data (c) e-nose data Figur
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In the case of FTIR, linear classif
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2.3.2.2 Class Prediction Accuracies
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Figure 2-7 Class prediction rates o
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The topology of the three-dimension
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Figure 2-9 Three-dimensional error
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Furthermore, a thorough comparison
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In the master/slave architecture, a
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precision of the classification acc
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Figure 3-3 The steps of the Nelder-
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3.3 Results and Discussion 3.3.1 Li
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3.3.2 Nonlinear Models In order to
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9) 10) 11) 12) 13) 14) 15) 16) Figu
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As an additional visual aid, these
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a) Number of iterations b) Number o
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Figure 3-10 Comparison of the execu
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Figure 3-12 Speedup produced by the
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4 Integration of Heterogeneous Data
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4.2.2 Procrustes Analysis Procruste
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symmetric method since the ordering
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Figure 4-3 Steps of CPCA for the da
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4.2.5 Data Integration and Analysis
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Figure 4-4 Data integration workflo
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a) GPA b) CPCA Figure 4-6 The conse
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accuracies as the linear models; po
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Figure 4-8 Classification Results f
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Similar to FTIR, the PLS-DA ensembl
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Figure 4-9 Class prediction rates o
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4.3.3 Permutation Tests Even though
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Even though the interpretation of t
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Figure 4-12 Distribution plots of t
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RBF SVMs Datasets Original %CC Mean
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Figure 4-14 Boxplots representing t
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5 Application of the multivariate a
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Figure 5-1 Mean FTIR spectra for ca
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5.2.2.2 Fourier Transform Infrared
Page 133 and 134: 5.2.2.4 Data Overview For each expe
Page 135 and 136: 5.2.3.3 High Throughput Liquid Chro
Page 137 and 138: Figure 5-5 displays the PCA scores
Page 139 and 140: (a) GPA (b) CPCA Figure 5-6 The con
Page 141 and 142: observation confirms that indeed CP
Page 143 and 144: Figure 5-8 Class prediction rates o
Page 145 and 146: (a) RBF SVMs (b) PLS-DA Figure 5-9
Page 147 and 148: RBF SVMs Datasets Original %CC Mean
Page 149 and 150: Figure 5-12 Execution times of the
Page 151 and 152: (a) FTIR data (b) Raman data Figure
Page 153 and 154: The classification results for the
Page 155 and 156: Figure 5-16 Class prediction rates
Page 157 and 158: (a) RBF SVMs (b) PLS-DA Figure 5-17
Page 161 and 162: Figure 5-20 Execution times of the
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Page 165 and 166: (a) GPA (b) CPCA Figure 5-22 The co
Page 167 and 168: The classification results of the f
Page 169 and 170: Figure 5-24 Classification Results
Page 171 and 172: Figure 5-25 Class prediction rates
Page 173 and 174: The permutation results for the dat
Page 175 and 176: Figure 5-28 Distribution plots of t
Page 179 and 180: Figure 5-30 Boxplots representing t
Page 181 and 182: 5.4 Comparison of the individual ca
Page 183: Figure 5-32 Investigating the commo
Page 187 and 188: 6.2.2 Generating static graphs As d
Page 189 and 190: Figure 6-2 Construction process of
Page 191 and 192: 6.2.2.2 Generating dynamic reports
Page 193 and 194: activity, while simultaneously the
Page 195 and 196: or disappeared (Wang et al., 2008).
Page 197 and 198: ectangles, circles and/or irregular
Page 199 and 200: In addition to the static figures g
Page 201 and 202: c) graphics package d) ggplot2 pack
Page 203 and 204: In addition to aesthetics, faceting
Page 205 and 206: Datasets FTIR HPLC e-nose PLS-DA (L
Page 207 and 208: Figure 6-10 Interactive dendrogram
Page 209 and 210: 6.4 Conclusion The work reported in
Page 211 and 212: large number of individual models i
Page 213 and 214: The generated suite of tools, as pr
Page 215 and 216: In addition, the difficulty to corr
Page 217 and 218: REFERENCES Almeida, J. A. S., Barbo
Page 219 and 220: Processing., Proceedings of the 12t
Page 221 and 222: Clarke, B., Fokoué, E. and Zhang,
Page 223 and 224: spectroscopy and machine learning",
Page 225 and 226: Gower, J. C. (1975), "Generalized p
Page 227 and 228: Jardon, M. (2006), Systems Biology:
Page 229 and 230: Nicolaou, N., Xu, Y. and Goodacre,
Page 231 and 232: Shah, A. A., Barthel, D., Lukasiak,
Page 233 and 234: Vera, G., Jansen, R. and Suppi, R.
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Xu, Y. and Goodacre, R. (2012), "Mu
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