The mathematical models for cutting force calculation during structural and corrosion-resistant steels` parts processing

The paper shows that conventional mathematical models for calculating the cutting force components during the turning process, represented in reference guides on engineering, give drastic errors reaching 100 percent or more for various tool-workpiece couples. These errors interfere with applying reference values of the cutting force for any further calculations, equipment selection, workpiece positioning scheme, workpiece deformation value due to the elastic of the technological system elements during processing and etc., because of the insufficient reliability of the results of such calculations. The paper proposes mathematical models obtained as a result of experimental studies, which allow for increasing the accuracy of the calculation of the components of the cutting force by introducing an additional parameter – i.e., the value of thermo EMF of the test running into the calculation formulas. This approach enables to reduce the error in the calculation of the components of the cutting force up to ± 15%. In addition, the need for the development of specific mathematical models for various groups of materials machined is shown, which is due to the peculiarities of contact processes in the machining of various groups of steels, as well as to qualitative and quantitative indicators of the thermo-physical properties of the materials of tool-workpiece contact couples

The role of the feedforward paradigm in cognitive psychology

Feedforward control is a process adjusting behaviour in a continuative way. Feedforward takes place when an equilibrium state is disrupted and the system has to automatically retrieve the homeostatic stable state. It also occurs when a perturbation is previewed and must be eliminated in order to achieve a desired goal. According to the most general definition, a feedforward process operates by fixing the future representation of the desired state, the achieving of which stops the process. Then, feedforward works by means of the refinement determined by successive comparisons between the actual and target products. In its applications, a feedforward process is thought to be modulated by the subject's purpose and the environmental state. Over the years, the feedforward process has assumed different connotations in several contests of cognitive psychology. An overview of the research fields in psychology that significantly progressed with the introduction of a feedforward paradigm is provided by: (a) reviewing models in which the feedforward concept plays a fundamental role in the system control; (b) examining critical experiments related to the interaction of feedforward and feedback processes; (c) evidencing practical applications for some of the presented feedforward-based architectures. © Marta Olivetti Belardinelli and Springer-Verlag 2006