This book contains scientific research from the doctoral thesis “Contributions to the scientific approach of quality and quality management” written by Assoc. Prof. PhD Amelia Bucur, thesis that was realized under the scientific coordination of Prof. PhD Eng. DHC Constantin Oprean. Moreover, the book contains new unique aspects and aspects published by the authors in papers or works presented at conferences. The book also presents a result of the research activity done within the project of post-doctoral research “Contributions to the scientific approach of quality and quality management by modeling and simulation”, however, it may also be bibliographic material for courses of “Operational research”.