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The k-medoids (k-median) problem is one of the best known unsupervised clustering problems. Due to its complexity, finding high-quality solutions for huge-scale datasets remains extremely challenging. The application of many approaches finding optimal or quality solutions is limited to only small and medium-size instances. On the other hand, many parallel, distributed algorithms that can handle huge-scale datasets usually provide very poor solutions. In this paper, we develop a first parallel, distributed primal–dual heuristic algorithm for the k-medoids problem. Its main component is a very efficient parallel subgradient column generation that solves a Lagrangian dual problem and finds a tight bound on solution quality. High-quality solutions are then produced by a parallel core selection technique. We considerably reduce computational burden and memory load by employing a nearest neighbor strategy to approximate the dissimilarity matrix. We demonstrate that our algorithm finds very close to optimal solutions, confirmed by the tightness of dual bounds, of instances that are much larger than those considered in the literature to date. Our experiments include clustering large-scale collections of face images into several thousand of clusters. We show that our approach outperforms parallel improved versions of the most popular k-medoids clustering algorithms, achieving nearly linear parallel speedup. [ABSTRACT FROM AUTHOR]

Corrosion protection of equipment, apparatus and thermal-stressed metal structures (which refer to equipment of fuel and power industries) operated under conditions of chemical manufacturing processes is the prime industrial target. Corrosive medium causes changes in material structure and properties resulting in decreased strength and premature damage of equipment [1].The subject of research is the system of thermal resistant protective coating for extreme operation conditions.The objective of the study is technology development of protective organic coating with predictable properties within the long-term operation of real gas-compressor units. The research resulted in improved procedure of thermogradient coatings application with positive progress due to the modification of layers of heat-resistant paintwork materials [2].

An interview with Center for Political Technologies President Igor Bunin is presented. He describes the main special features of the regional elections to be held in Russia on September 8, 2013. He discussed the possibility of returning Vladislav Surkov in politics after being dismissed as deputy prime minister. Particular focus is also given to the criticisms on the performance of first deputy presidential chief of staff Vyacheslav Volodin in Russian and Western media.