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This paper presents an approach of empirical modeling of the machining process physical quantity with measurement uncertainty parameter included in the resulting power mathematical model coefficients. The proposed approach is presented through an example of modeling of the average temperature in turning like a methodology that is under the influence of various sources of measurement errors. The uncertainty budget accounts for the sources of errors of the experimental measuring system and the cutting process itself. This approach enables estimation of the reliability of the gained mathematical models and gives the possibility of identification and lowering of the main sources of errors.

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Advancements in power electronics that contributed to the easier starting of synchronous permanent magnet motors have increased the significance of this type of motors, widely known as not–self-starting motors. However, power electronics, which is necessary, for the starting of the synchronous motor contributed also to the complexity of this type of motor drives as well as to increased operational and maintenance cost. The line-start synchronous motors have gained the popularity during recent years as a viable alternative to asynchronous motors due to an easy line starting similar to the asynchronous motors and good operational parameters such as high efficiency and power factor. The paper presents the design of a line-start synchronous motor, derived from an asynchronous motor, by redesigning the rotor with flux barriers and permanent magnets. The computer models for calculating parameters and operating characteristics of both motors were modeled and the accuracy of the obtained results was verified by comparison with experimental data. Motor transient characteristics of speed, current and torque for the line starting of the both motors, when they were fed with the voltage from the network, were determined as well. The obtained transient characteristics of both motors were compared and adequate conclusions regarding line starting of both motors were derived. The newly derived synchronous motor for line starting has good operational characteristics such as increased efficiency, power factor and starting torque compared with the respected parameters of the asynchronous motor, good transient and steady-state operating characteristics and good dynamic response at sudden load change.

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