This article proposes a stochastic optimisation model in order to reduce the long-term total maintenance cost of complex systems. The proposed work is based on the following approaches: (i) optimisation of a cost model for complex multi-component systems consisting of preventive and corrective maintenance using reliability analysis, which faces two different maintenance policies (periodic block-type and age-based) and (ii) a clustering method for maintenance actions to decrease the total maintenance cost of the complex system. This work evaluates each maintenance policy and measures the effects on imperfect maintenance actions. Finally, the proposed optimisation model is applied to a numerical example which focuses on passenger urban aerial ropeway transport systems, in which the current maintenance policy has been evaluated, considering the established by the international regulation of passenger aerial cable cars.

The technique of structural analysis in foresight study from the Faculty of Economic and Administrative Sciences of Instituto Tecnológico Metropolitano-ITM Medellin, Colombia allowed defining the strategic variables that will guide its strengthening in 2020. The aim of this article is to present the conceptual references of the technique and results of the implementation of MICMAC to determine the degree of influence and dependence variables. The methodology used to achieve the objective was the analysis of 55 key variables that were prioritized because of their importance to determine the 15 strategic variables that have to project the future actions taking into account the situation of autonomy, power, conflict and output. In this regard, it is concluded on the relevance of the variables in the power

The cutting drums are the basic working components of many mining machines. The article focuses on differences in the design of cutting drums depending on the expected working conditions. Then, the unique calculation procedure is presented which allows to determine the load on the unit by reducing the forces acting on a single pick, taking into account the picks bent on the cut-off disc. Until now, this has been omitted in the literature. The results of the calculations for the selected cutting drum performed in MATLAB are also presented. The further section proposes to use Autodesk Inventor Professional's iLogic Tool for quick modelling of cutting drums. The principles of creating parameterized models and compositions using programming elements in the form of iLogic scripts are presented. The articles presented a ready-made units generator, taking into account the possibility to determine values of selected numerical parameters of the unit: diameter, web, number of patches and cutting pitch. The generator also allows you to select the type of pick holders, conical pick types, as well as the choice of pick system for repositioning or matching picks.

This paper proposes a continuous inspection method to assess the journey safety applied to aerial cable vehicles of mass transportation;a type of detachable gondola liftin terms of commercial operation in an urban area, specifically referring to the device coupling assembly on the track rope. The inspection method has been developed on the basis of a continual measurement process of the recorded strain conditions on a principal component of the coupling assembly. The selected component is commonly referred to as moving jaw. The proposed inspection procedure is structured based on the following set of consecutive stages: (i) Downloaded by [Simon Fraser University] at 02:56 17 March 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 characterization of the load states generated by the commercial operation of the system; (ii) definition of the sections of greater sensitivity to the strains caused by the load states, by means of Finite Elements; (iii) development of a measurement system; (iv) calibration of the measuring system with controlled tests; and (v) implementation and continuous records data in commercial operation.

This paper presents a methodology to evaluate the technical state of a Francis turbine by shaft rotor dynamic simulation. There are several rotor dynamic criteria that define the technical state of a turbo-machine. To feed the shaft rotor dynamic model this delivers the required information to accomplish the technical assessment. The numerical rotor dynamic model uses as input, the field forces obtained by the fluid-solid interaction analysis undertaken over the blades of the runner. The rotor dynamic numerical simulations allow to determinate the record-in-time of the displacements of any point along the shaft. This information is relevant for diagnosis tasks, because it is possible to decompose it spectrally and to estimate the severity of the vibrations. Comparing the results of the numerical model against those obtained from machines that operates under normal conditions, it is possible to determinate the technical state of the turbo-machine. This allows studying the stability of the turbine working on several operation ranges. A Francis turbine is a very complex machine that involves many physical phenomena of different nature.In this way, the hydraulic input forces needed by the rotor dynamic model should not be assumed but calculated directly from the fluid interaction over the turbine structure.