Book excerpt: The book is a collection of high-quality peer-reviewed research papers presented at the International Conference of Experimental and Numerical Investigations and New Technologies (CNNTech2021) held at Zlatibor, Serbia, from June 29 to July 2, 2021. The book discusses a wide variety of industrial, engineering, and scientific applications of the engineering techniques. Researchers from academia and industry present their original work and exchange ideas, experiences, information, techniques, applications, and innovations in the field of mechanical engineering, materials science, chemical and process engineering, experimental techniques, numerical methods, and new technologies.