In the paper, a new method was presented using queueing theory models in order to ensure an optimal production department size, optimized production costs and optimal provision. Queueing/waiting mathematical models represent the development matrix for an experimental algorithm and implicitly numerical approach, both successfully applied (and confirmed in practice) in a production section design for a real industrial engineering unit with discussed method technological flow and equipment schemes compatibility. The total costs for a queueing system with S servers depend on the number of servers. The problem of minimizing cost in terms of S was the main aim of the paper. In order to solve it, we estimated all the variables of the system that influence the cost using the Monte Carlo method. For a Jackson queueing network, the involved linear system has good properties such that it can be solved by iterative methods such as Jacobi and Gauss–Seidel.

This article includes several studies and advanced research carried out on the subject of large KANGUR-type port cranes, subjected to regular or interventional maintenance work; besides the beneficial effects for which they were intended, some undesirable effects were detected in terms of affecting safety in exploitation. The purpose of this paper is to identify the risk factors and to offer sustainable solutions for increasing operational safety and service life for the respective equipment, as well as for other similar fields of activity, including oversized structures. Following the theoretical studies and the experimental research carried out in situ that confirmed the validity of the theoretical models used, the article in conclusion provides specific and sustainable solutions as well as new methods of assessment, which combine the positive elements of the usual solutions, but in parallel, allow the elimination of the negative side effects that may occur in time. Hence, the article’s novelties also consist of a new approach to achieve structural interventions, resulting in the increase in the service life, and in parallel with that, the safety in operation of the respective equipment.

The properties of a composite material are determined by the properties of the constitutive materials. In engineering practice, there are many situations in which we have composite material, but we do not have information about the properties of each phase component. The measurements we can make in such cases are on the existing material, thus being able to determine, experimentally, the global physical properties of the composite. The possibility of realizing an estimate of the mechanical properties of each component poses a problem if we start from these measurements. The paper proposes a method to achieve this, starting from the theoretical estimates established in the literature, then illustrated by an example to determine the properties of wood. Wood is a transverse isotropic material and therefore the constitutive law has symmetries that are manifested in the decrease of the number of parameters that define the stress-strain liason, defined only by five independent parameters. The proposed method can be extended to a diversity of models and materials used in the study of composite materials.