Composite laminate materials are used extensively in various applications particularly in aircraft structures. During operation, the aircraft’s structure will experience mechanical responses due to environmental degradation or external damages. This mechanical loading may cause damages to further develop in the composite laminate materials. Thus, numerous attempts from previous researchers to develop theories to investigate the damage that appears in composite laminate materials under loading conditions. Therefore, this review paper presents an overview of theoretical models that have been used to investigate the effects on stiffness due to the damage mechanism in composite laminate materials under fatigue loading conditions specifically.

Coherent motions depict the individuals’ collective movements in widely existing moving crowds in physical, biological, and other systems. In recent years, similarity-based clustering algorithms, particularly the Coherent Filtering (CF) clustering approach, have accomplished wide-scale popularity and acceptance in the field of coherent motion detection. In this work, a tracklet-before-clustering initialization strategy is introduced to enhance coherent motion detection. Moreover, a Hierarchical Tracklet Association (HTA) algorithm is proposed to address the disconnected KLT tracklets problem of the input motion feature, thereby making proper trajectories repair to optimize the CF performance of the moving crowd clustering. The experimental results showed that the proposed method is effective and capable of extracting significant motion patterns taken from crowd scenes. Quantitative evaluation methods, such as Purity, Normalized Mutual Information Index (NMI), Rand Index (RI), and F-measure (Fm), were conducted on real-world data using a huge number of video clips. This work has established a key, initial step toward achieving rich pattern recognition.