The cluster evaluation process is of great importance in areas of machine learning and data mining. Evaluating the clustering quality of clusters shows how much any proposed approach or algorithm is competent. Nevertheless, evaluating the quality of any cluster is still an issue. Although many cluster validity indices have been proposed, there is a need for new approaches that can measure the clustering quality more accurately because most of the existing approaches measure the cluster quality correctly when the shape of the cluster is spherical. However, very few clusters in the real world are spherical. Therefore, a new Validity Index for Arbitrary-Shaped Clusters based on the kernel density estimation (the VIASCKDE Index) to overcome the mentioned issue was proposed in the study. In the VIASCKDE Index, we used separation and compactness of each data to support arbitrary-shaped clusters and utilized the kernel density estimation (KDE) to give more weight to the denser areas in the clusters to support cluster compactness. To evaluate the performance of our approach, we compared it to the state-of-the-art cluster validity indices. Experimental results have demonstrated that the VIASCKDE Index outperforms the compared indices.

Stream clustering has emerged as a vital area for processing streaming data in real-time, facilitating the extraction of meaningful information. While efficient approaches for defining and updating clusters based on similarity criteria have been proposed, outliers and noisy data within stream clustering areas pose a significant threat to the overall performance of clustering algorithms. Moreover, the limitation of existing methods in generating non-spherical clusters underscores the need for improved clustering quality. As a new methodology, we propose a new stream clustering approach, MCMSTStream, to overcome the abovementioned challenges. The algorithm applies MST to micro-clusters defined by using the KD-Tree data structure to define macro-clusters. MCMSTStream is robust against outliers and noisy data and has the ability to define clusters with arbitrary shapes. Furthermore, the proposed algorithm exhibits notable speed and can handling high-dimensional data. ARI and Purity indices are used to prove the clustering success of the MCMSTStream. The evaluation results reveal the superior performance of MCMSTStream compared to state-of-the-art stream clustering algorithms such as DenStream, DBSTREAM, and KD-AR Stream. The proposed method obtained a Purity value of 0.9780 and an ARI value of 0.7509, the highest scores for the KDD dataset. In the other 11 datasets, it obtained much higher results than its competitors. As a result, the proposed method is an effective stream clustering algorithm on datasets with outliers, high-dimensional, and arbitrary-shaped clusters. In addition, its runtime performance is also quite reasonable.

Deceptive and evolving conversations on online platforms threaten trust, security, and user safety, particularly when concept drift obscures malicious intent. Large Language Models (LLMs) offer strong natural language reasoning but remain unreliable in risk-sensitive scenarios due to contextual ambiguity and hallucinations. This article introduces a domain knowledge-enhanced Dual-LLM framework that integrates structured cues with pretrained models to improve fraud detection and drift classification. The proposed approach achieves 98% accuracy on benchmark datasets, significantly outperforming zero-shot LLMs and traditional classifiers. The results highlight how domain-grounded prompts enhance both accuracy and interpretability, offering a trustworthy path for applying LLMs in safety-critical applications. Beyond advancing the state of the art in fraud detection, this work has the potential to benefit domains such as cybersecurity, e-commerce, financial fraud prevention, and online content moderation.

Teknolojideki gelişmeler, insanların pek çok farklı kaynakta üretilen verileri toplamasına ve analiz etmesine imkân tanımıştır. Sensörler, mobil cihazlar, nesnelerin interneti gibi yapılarda üretilen veriler akan veri formatında olup, bu tür verilerden işlenerek faydalı bilgilerin elde edilmesi zor bir problemdir. Akan verileri analiz etmek için sıklıkla kullanılan yöntemlerden birisi olan kümelemede, veriler dağılımlarına göre çeşitli gruplara ayrılarak analiz edilir. Bu çalışmada, akan veri kümeleme problemi için iki yeni algoritma geliştirilerek literatürdeki başka bir yöntemle karşılaştırılmıştır. Farklı veri kümeleri üzerinde yapılan deneyler neticesinde, geliştirilen algoritmaların iyi sonuçlar verdiği görülmüştür.