Add Literature Review (#80)

* feat(latex): add initial literature review paragraph from paper which data I used #67

* feat(latex): add Indonesian translation of structural health monitoring methods and related research findings

* feat(latex): add theoretical foundations and classification algorithms for damage localization in english version

* feat(latex): add initial content for literature review in index.tex

* Update latex/chapters/en/02_literature_review/index.tex

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

latex/chapters/en/02_literature_review/index.tex

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+\chapter{LITERATURE REVIEW AND THEORETICAL FOUNDATION}
+\section{Literature Review}
+\input{chapters/id/02_literature_review/literature_review/abdeljaber2017}
+
+\section{Theoretical Foundation}
+\input{chapters/id/02_literature_review/theoritical_foundation/stft}
+\input{chapters/id/02_literature_review/theoritical_foundation/machine_learning}
+
+\bigskip
+These theoretical foundations provide the methodological framework for implementing and evaluating the proposed damage localization system in this research. The combination of time-frequency analysis using STFT and classical machine learning classifiers enables an efficient and interpretable approach to structural health monitoring.

latex/chapters/en/02_literature_review/literature_review/abdeljaber2017.tex

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+Traditional structural health monitoring methods often rely on hand-crafted features and manually tuned classifiers, which pose challenges in terms of generalization, reliability, and computational efficiency. As highlighted by [Author(s), Year], these approaches frequently require a trial-and-error process for feature and classifier selection, which not only reduces their robustness across structures but also hinders their deployment in real-time applications due to the computational load of the feature extraction phase.
+
+[Author(s), Year] introduced a CNN-based structural damage detection approach validated through a large-scale grandstand simulator at Qatar University. The structure, designed to replicate modern stadiums, was equipped with 30 accelerometers and subjected to controlled damage by loosening beam-to-girder bolts. Acceleration data, collected under band-limited white noise excitation and sampled at 1024 Hz, were segmented into 128-sample frames for training localized 1D CNNs—one per joint—creating a decentralized detection system. Across two experimental phases, involving both partial and full-structure monitoring, the method demonstrated high accuracy in damage localization, achieving a training classification error of just 0.54\%. While performance remained strong even under double-damage scenarios, some misclassifications occurred in symmetric or adjacent damage cases. Overall, the proposed method presents a highly efficient and accurate solution for real-time SHM applications.
+
+In the context of this thesis, the dataset and experimental setup introduced by [Author(s), Year] form the foundation for comparative analysis and algorithm testing. The authors have not only demonstrated the efficacy of a compact 1D CNN-based system for vibration-based structural damage detection, but also highlighted the value of using output-only acceleration data—a constraint shared in this thesis’s methodology. The decentralized design of their system, which allows each CNN to process only locally available data, is particularly aligned with this thesis's focus on efficient, sensor-level data analysis without requiring full-system synchronization. Furthermore, since the authors indicate plans to publicly release their dataset and source code, this thesis leverages that open data for applying alternative analysis methods such as support vector machines (SVM) or frequency domain feature extraction techniques, allowing a direct performance comparison between classical and deep learning-based SHM approaches. Thus, this work serves as both a benchmark reference and a data source in the development and evaluation of more accessible, lower-complexity alternatives for structural health monitoring systems.
+

latex/chapters/en/02_literature_review/theoritical_foundation/machine_learning.tex

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+\subsection{Classification Algorithms}
+
+This research evaluates five classical machine learning algorithms to perform the classification task of damage localization. Each algorithm has different strengths and limitations, and their performance is benchmarked to identify the most suitable one for the given dataset.
+
+\subsubsection{Support Vector Machine (SVM)}
+
+SVM is a supervised learning algorithm that seeks an optimal hyperplane that separates data into classes with maximum margin. SVM performs well in high-dimensional spaces and is robust to overfitting, especially in cases with a clear margin of separation.
+
+SVM is appropriate for vibration signal classification due to its capability to handle nonlinear decision boundaries when equipped with kernel functions.
+
+\subsubsection{K-Nearest Neighbors (KNN)}
+
+KNN is a non-parametric, instance-based learning algorithm. It classifies a new data point based on the majority vote of its $k$ nearest neighbors in the feature space. Although simple, KNN can be effective when the data is well-distributed and class boundaries are smooth.
+
+Its performance is sensitive to the choice of $k$ and distance metric. For high-dimensional data like STFT features, dimensionality reduction or careful scaling may be required.
+
+\subsubsection{Decision Tree (DT)}
+
+Decision Tree is a rule-based classifier that splits data into classes using feature thresholds. It builds a tree where each internal node represents a feature, each branch a decision rule, and each leaf a class label. DTs are easy to interpret and can capture non-linear relationships.
+
+However, they are prone to overfitting, especially with noisy or small datasets.
+
+\subsubsection{Random Forest (RF)}
+
+Random Forest is an ensemble learning method based on constructing multiple decision trees during training and outputting the mode of the classes for classification. It improves the generalization capability of individual trees and reduces overfitting.
+
+RF is suitable for damage detection as it provides robustness to noise and variance, making it ideal for real-world sensor data.
+
+\subsubsection{Naïve Bayes (NB)}
+
+Naïve Bayes is a probabilistic classifier based on Bayes' theorem, assuming feature independence. Despite its simplicity, it often performs well in high-dimensional problems and with small datasets.
+
+NB is particularly effective when class-conditional independence holds approximately, which may occur when STFT features are well-separated in distribution.

latex/chapters/en/02_literature_review/theoritical_foundation/stft.tex

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+\subsection{Short-Time Fourier Transform (STFT)}
+
+The Short-Time Fourier Transform (STFT) is a fundamental technique used to analyze non-stationary signals, such as those generated by structures under dynamic load or white noise excitation. While the traditional Fourier Transform provides frequency-domain information, it lacks time resolution. STFT overcomes this limitation by applying the Fourier Transform over short overlapping segments of the signal, thereby producing a time-frequency representation.
+
+Mathematically, the STFT of a signal $x(t)$ is given by:
+\begin{equation}
+X(t, \omega) = \int_{-\infty}^{\infty} x(\tau) w(\tau - t) e^{-j \omega \tau} d\tau
+\end{equation}
+where $w(\tau - t)$ is a window function centered at time $t$, and $\omega$ is the angular frequency.
+
+In this study, the STFT is employed to extract the time-frequency features of the vibration signals collected from the structure. These features are then used as inputs to machine learning classifiers. This process captures localized frequency content over time, which is crucial in identifying structural changes due to damage.