Sharif Digital Repository

Oil analysis technique is used as predictive and proactive tools to identify the wear modes of rubbing parts and to diagnose the faults in machinery. In this paper, the wear behavior of diesel engines, especially on oil analysis, is studied based on condition data. In terms of analyzing historical data, descriptive statistics is used as data mining tools to find the relationship between condition factors of the machine and its final status. The equipments have been monitored in two different environments which are: plantation-forestry, and general construction. Based on this relationship a specific baseline is achieved for selected sets of equipment in their specific conditions. A striking... 

Coordinate Measuring Machines (CMMs) are designed for precision inspection of complex industrial products. The mechanical accuracy of CMMs depends on both static and dynamic sources of error. In automated CMMs, one of the dynamic error sources is vibration of the probe, due to inertia forces resulting from parts acceleration and deceleration. Modeling of a gantry type CMM, based on the Timoshenko beam theory with moving mass effects, is developed and the dynamic errors of the probe resulting from the acceleration and deceleration of moving parts, are calculated. Findings from analytical solution and dynamic modeling software indicate high accuracy and good agreement between the results. ©... 

Coordinate Measuring Machines (CMMs) are designed for precision inspection of complex industrial products. Even though CMMs have high accuracy in electrical systems, mechanical structures prevent very high accuracy in these machines. Mechanical accuracy of CMMs depends on both static and dynamic sources of error. In automated CMMs, one of the dynamic error sources is the vibration of probes, due to inertia forces resulting from parts deceleration. Modeling of a gantry type CMM, based on the Timoshenko beam theory, is developed and the natural frequencies of the CMM system, at different positions of the probe, are calculated. Findings from the analytical and finite elements method indicate... 

Landfill leachate is a highly contaminated liquid generated in municipal solid waste landfills. The application of sulfate radical-based advanced oxidation processes (SR-AOP) in landfill leachate treatments is emerging due to their ability to degrade both organic refractory matters and ammonia nitrogen. In this paper, application of peroxymonosulfate (PMS), activated by Fe2+ and UV was used as an economical and environmentally friendly approach for treatment of landfill leachate. Chemical oxygen demand (COD) and ammonia removals were measured as the two primary responses of landfill leachate to UV/PMS/Fe2+ treatment system. The main parameters (pH, PMS/Fe2+ mass ratio, Fe2+ dosage) affecting... 

In this study, a new mathematical programming approach for solving the joint timetabling and train stop planning problem in a railway line with double-track segments is proposed. This research aims to design an optimized train timetable subject to the station- capacity and time-dependent dwell time constraints. The objective function is to maximize the railway infrastructure capacity by minimizing the schedule makespan. The problem is formulated as a particular case of blocking permutation flexible flow shop scheduling model with dynamic time window constraints. Due to the combinatorial nature of the problem, heuristic algorithm and bound tightening methods are proposed that generate...