This paper presents an iterative method based on conformal mapping and magnetic equivalent circuits for on-load analysis of saturated surface permanent magnet machines with integer slot and fractional slot windings. Magnetic saturation is taken into account by defining additional point wires in the stator slots and interpolar region between the magnets. The added point wires create magnetomotive force equal to the magnetic voltage drops across iron core flux tubes which are calculated using magnetic equivalent circuit. An improved stator tooth model has been introduced which enables more accurate field calculations for tooth geometries with highly saturated tooth tips. The model also takes into account variation of permanent magnet magnetization due to external magnetic field. The proposed method has been implemented on a saturated 12 slot, 10 pole surface permanent magnet machine with nonoverlapping concentrated winding and shows a very good agreement with finite element calculations in terms of flux density, back electromotive force and torque waveforms as well as d and q axis inductances, cross-saturation inductance and permanent magnet flux linkage in both axes.

Specific energy is the measure which connects the operating parameters of the machine with the characteristics of the rock in which the machine works and is equal to the total work required to break a unit volume of the rock. It is...

A method based on extensive laboratory and field measurements was developed to determine the dependence of specific rock cutting energy (SEc) on specific drilling energy (SEd) for machines with different operating and design characteristics and similar breaking mechanics. Laboratory measurements were performed on a linear rock cutting device and a laboratory drill, using a measurement system to measure electrical power and cutting forces using force/torque transducers. Field power consumption measurements were performed on a chainsaw cutting machine and a hydraulic rotary drill under real working conditions in the dimension stone quarries. The analysis of the measured results confirmed the strong dependence of the specific rock cutting energy on the specific drilling energy and confirmed that laboratory devices can be used to simulate actual rock cutting and drilling process. In addition, the results are applicable in the dimension stone exploration and exploitation phase in order to assess and reduce energy consumption by optimizing the operating parameters of the chain cutter and/or the hydraulic rotary drill.

Vibrating wire sensors are used for strain measurement. Sensing is based in frequency change when tension of wire changes. Here are considered other possibilities of vibrating wire strain gauge implementations and their properties. It includes change in frequency with change in length and some implementations with sliding contact. Last implementation consists of firm beam and short segment of wire which allows better sensitivity of sensor giving substantially larger increase of frequency for small increase in strain.