In directional drilling, the most important thing that leads to pulling out the drill string is end of mud motor working life. Considering the working conditions of down hole mud motors; increasing the mechanical properties of their stator’s elastomer is crucial. Some attempts were done to increase the motor performance through geometrical changes but lack of material improvement is significant...

Drilling performance prediction, using traditional mechanics of cutting approach, is based on the extension of three-dimensional oblique cutting theory. The quantitative reliability of such conventional models depend on a numerous number process variables and quantitative accuracy of the data bank for a given work material. The complexity of such models is increased when inevitable eccentricity...

The present study encompasses a new method to simultaneous analysis, design and optimization of Water Distribution Systems (WDSs). In this method, analysis procedure is carried out using Charged System Search (CSS) optimization algorithm. Besides design and cost optimization of WDSs are performed simultaneous with analysis process using a new objective function in order to satisfying the analys...

Preventive maintenance is a means to ensure the component kept in desired state. Lack of preventive will cause unexpected consequences for component, and too much result unnecessary investment resources. Based on reliability data this paper establishes an analysis model determine optimal interval make cost corrective lowest.

Reliability is an important engineering requirement for consistently delivering acceptable product performance through time. It also affects the scheduling for preventive maintenance. Reliability usually degrades with time increasing therefore, the lifecycle cost due to more frequent failures which result in increased warranty costs, costly repairs and loss of market share. In a lifecycle cost ...

in today's competitive market, quality has an important role in manufacturing system. the manufacturers attempt to maintain their production system in a proper condition to produce high quality products. one of the key factors to achieve this goal is maintenance policy. most studies on maintenance focused on machines and less attention has been paid to human resources as the most important...

the present study is concerned with the simultaneous optimization of the size of components and the arrangement of connections for performance-based seismic design of low-rise spsws. design variables include the size of beams and columns, the thickness of the infill panels, the type of each beam-to-column connection and the type of each infill-to-boundary frame connection. the objective functio...

this paper addresses the mixed integer reliability redundancy allocation problems to determine simultaneous allocation of optimal reliability and redundancy level of components based on three objective goals. system engineering principles suggest that the best design is the design that maximizes the system operational effectiveness and at the same time minimizes the total cost of ownership (tco...