# Systems Engineering: Availability and Reliability
## 5 Systems Analysis, Simulation, Design and Modeling
As oil viscosity is essential for all lubricated tribopairs for wear and friction reduction in all vehicles with a gearbox, it may be influenced by the contamination that wear products can impart on the oil. Oil contamination can also affect lubrication efficiency in the boundary friction conditions in gearboxes where slips occur (including bevel and hypoid gearboxes). Therefore, the present research [13] focused on this issue. An obvious hypothesis was adopted, where it was theorized that exploiting the contaminants that are present in gear oil may affect how the lubricating properties of gear oils deteriorate. Laboratory tests were performed on contaminants that are commonly found in gear oil. The study was designed to identify a number of different solid particles that are present in oil. The quantitative contamination of the gear oils that contained solid particles and the curves representing the friction coefficients of fresh oils with a history of exploitation were compared. Exploitation was shown to have a significant impact on the contamination of gear oils. It was revealed that the contamination and the mileage had no effect on the tested oils. The research [13] showed that the presence of contaminants is not catastrophic and that in order to fully examine the oils and to determine the critical moment, the oils with a much greater operational mileage should be tested in order to establish the relationship between the number of particles and their tribological properties. Various factors are considered in system design, such as efficiency, costs, safety, and environmental effect. Availability is also one of the important issues in system design. The availability indicates how much a system approaches ideal operation without production loss caused by equipment failures or undesired external events. Availability estimation is frequently performed in the oil and gas, chemical and power plant industries to find the optimum design option, to predict the production level and to evaluate maintenance and operating policies. Precise availability estimation is important because it directly influences the owner's decision. This is why [PERSON] et al. [14] have investigated the availability gap between the early and late design stages by estimating it with the design stages to find a practical manner of availability estimation in the early design stage. The sensitivity analysis was conducted to analyze the key factors in the results. The most crucial factor was the redundant equipment. Although this study [14] did not consider the whole system, this gives an important guide to progress the next step for the accurate availability estimation in the early design stage. Steel tapes with certain special markings generated on their surface are often used for metrological and technological purposes, for example, to measure displacement. The smoothness of the movement of a moving precision tape and the stability of the tape area where symbols are generated are very important factors that affect the quality parameters of a generated tape. One of the most important characteristics of the raster generation device is the smoothness of the stretching of the tape, which is important for the overall operation of the system. The smoothness of the stretching of the tape affects errors in the position of the raster element being generated and the control of activation of the laser beam. Determining not only the amplitude but also the frequency of the belt stretching oscillations is important. For this purpose, [15] analyzes the tape movement system consisting of electromechanical tape pulling and its constant stretching mechanisms as well as a tape deflection mechanism, which operates in sliding friction. This system was mounted on a massive granite base placed on a foundation using passive vibration insulation supports. A research and data processing method together with the results of experimental research of a mock-up system were developed and presented to examine the raster generation method and the generation device.