Iranian Journal of Materials Science and Engineering

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Abstract: Due to the expansion of high voltage Alternating Current (AC) power transmission lines and cathodically protected buried pipelines, it is becoming more and more difficult to construct them with enough safe distances between them. Thus, the pipelines are frequently exposed to induced AC interferences, which result in perturbation of Cathodic Protection (CP) due to AC corrosion. To study the above criterion, an experimental set up was used with coupons exposed to simulated soil solutions, while under both CP and AC induced condition for which an AC+DC power supply was utilized. The experiments were carried out in several simulated soil solutions corresponding to several soil samples collected from various regions along a buried pipeline with overhead parallel high voltage power transmission line. The results indicated that AC corrosion depends strongly on the composition of the soil.

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Abstract: The risks of alternating current (AC) corrosion and overprotection increasingly demand new criteria for
cathodically protected pipelines. To assess the risk of AC corrosion, new cathodic protection (CP) criteria have been
proposed based on DC/AC current densities measurements using coupons. The monitoring system designed for this
project was based on the instant-off method, with steel coupons simulating coating defects on a buried pipeline. The
problems associated with the instantaneous off-potential measurements have been attributed to a non-sufficient time
resolution. In present study, it has been possible to determine the de-polarisation of steel coupon within a few
milliseconds after disconnecting the coupon from the DC/AC power source, by increasing data acquisition rate. For
this, a monitoring system was developed in order to measure the IR-free potential together with the DC/AC current
densities. The monitoring system was utilized for both laboratory experiments and site survey to study the mechanism
and the condition of AC corrosion, its mitigation and more importantly to define new CP criteria.

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In automation flexible manufacturing systems, tool wear detection during the cutting process is one of the most important considerations. This study presents an intelligent system for online tool condition monitoring in drilling process .In this paper, analytical and empirical models have been used to predict the thrust and cutting forces on the lip and chisel edges of a new drill. Also an empirical model is used to estimate tool wear rate and force values on the edges of the worn drill. By using of the block diagram of machine tool drives, the changes in the feed and spindle motor currents are simulated, as wear rate increases. To predict tool wear rate in drill, Fuzzy logic capabilities have been used to develop intelligent system. The simulated results presented in MATLAB software show the effectiveness of the proposed system for on-line drill wear monitoring.

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On time replacement of a cutting tool with a new one is an important task in Flexible Manufacturing Systems (FMS). A fuzzy logic-based approach was used in the present study to predict and simulate the tool wear progress in turning operation. Cutting parameters and cutting forces were considered as the input and the wear rate was regarded as the output data in the fuzzy logic for constructing the system. Flank wear was used as the tool life criterion and the wear ranges were selected between 0 and 0, 3 based on ISO 3685 standard for new and worn tool respectively. For conducting the tests, Taghuchi method was used to design an experimental table. The results of the measurements and estimates confirmed the reliability of the fuzzy logic method for estimating tool wear. One significant feature of the proposed system is that it can predict the wear rate on-line by transferring the cutting force signals from the sensor to the fuzzy logic simulation box.