Papers by Keyword: Variation Law

Abstract: Internal defect of mortar finishing layer was detected using thermal infrared imager. The main object was to study variable characteristics of surface temperature on internal defect of mortar finishing layer heated by external heating source. The distribution and variation law of surface temperature on mortar finishing with time and space were obtained,and the influences of thickness,area and embedded depth of internal defect on image quality were analyzed. The test results show that the thicker, bigger and shallower internal defect is more easily detected. The surface mortar temperatures of internal defect is maximum temperature point of approximate symmetry along the width direction. Based on the test results, the prediction model of dimension of internal defect was established through statistical analysis technique, which can provide a reference for the related follow-up study and practical project application.

Abstract: This paper presents investigation results of the influence of the supply voltage amplitude variation law on the efficiency of AC induction motor in variable-speed drive based on the frequency converter. It is demonstrated that the commonly employed linear and square voltage amplitude variation laws do not provide the highest efficiency of the AC induction motor. The corrected AC voltage amplitude variation dependences for different motor load torque, at which high efficiency of the motor supplied by the frequency converter is maintained, are proposed and discussed. Reported experimental study was performed on a special test bench.