Application of Cardio-Forecasting for Evaluation of Human—Operator Performance

The paper presents the results of the development of the cardio-forecasting technology, which introduces a new method to monitor the state of human-operator, which is characteristic for the given production conditions and for individual operators, to predict the moment of exhaustion of his/her working capacity. The work aims to demonstrate the unique, distinctive features of the cardio-forecasting technology for predicting an individual limit of his/her working capacity for each person. A unique methodology for predicting individually for each person the moment when he/she reaches the limit of his/her working capacity is based on a spectral analysis of a human phonocardiogram in order to isolate the frequency component located at the heart contraction frequency. The trend of the amplitude of this component is approximated by its model; consequently, the coefficients of the trend model are determined. They include the operator’s operating time until his/her working capacity is exhausted. A methodology for predicting the moment when he/she reaches the limit of his/her working capacity for each person individually and assessment based on this degree of criticality of their condition will be realized as a software application for smartphones using the Android operating system

Method of Using the Correlation between the Surface Roughness of Metallic Materials and the Sound Generated during the Controlled Machining Process

The article aims to use the generated sound as operational information needed for adaptive control of the metalworking process and early monitoring and diagnosis of the condition of the machined materials using a newly introduced surface roughness quality index due to the sound-controlled machining process. The object of the measurement was correlation between the sound intensity generated during cutting and the material parameters of the machined surface, i.e., the roughness of the machined surface and the degree of wear of the cutting tool. The roughness was measured during longitudinal turning of a steel billet with a P25 insert made of 12X18H10T steel and a T15K6 cutting insert made of a titanium, cobalt, and tungsten group alloy. The correlation between the sound and roughness of the machined surface was 0.93, whereas between the sound and wear of the cutting tool was 0.93. The correlation between sound and tool wear in the experiment with P25 and T15K6 cutting inserts and the correlation between sound and roughness is positive

Determination of technologically optimal factors of modulated waterjet

This paper deals with two methods of determination of technologically optimal factors of a hydrodynamic resonance system leading to the acquiring of maximal fundamental frequency, amplitude, pressure, and energy of oscillations of a liquid jet. These factors are determined by the differential method and the method of state space search into depth. Furthermore, theoretically predicted results are presented, interpreted, and compared with results of laboratory measurements. The benefit of the study is the optimization itself, either for the optimal input factors of the prototype or a maximum possible modification of existing equipment in order to achieve the highest possible material disintegration efficiency.Web of Science601-417917

Analysis of acoustic emission emerging during hydroabrasive cutting and options for indirect quality control

The paper discusses connections of acoustic emission in abrasive water jet cutting. Introduction focuses on theoretical knowledge on this technology and offers analysis related to current state of the art of the problem research. Further description of performed experiments is presented in case in which acoustic emission behaviour was observed with the exactly scheduled change of cutting conditions or rather cutting head traverse speed v. The beginning of the initial part contains FFT spectral analyses and comparison of the examined sections of the experimental samples. Consequently a graphical representation and comparison of peak-to-peak values (maximal amplitudes) and values of AERMS at the time of experimental cutting follow. At the close of the work, the analyses are expressed as dependence on the cutting head traverse speed v with expressed regulation equations applicable in the close-loop control process with minimum human intervention and in case of fault conditions—broken focusing tube, fractured water nozzle.Web of Science661-4584