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Five-axis ball-end milling has been used extensively in the manufacturing of parts with sculptured surfaces. This paper presents the general cutting dynamics model of ball-end milling process for machine tools with different five-axis configurations. The structural dynamics of both the tool and workpiece are considered for the prediction of chatter stability at each tool location along the tool path. The effects of tool-workpiece engagement (TWE) and tool axis orientation are included in the model. By sweeping the spindle speeds, the chatter-free spindle speeds are selected followed by the prediction of forced vibrations in five-axis milling of thin-walled, flexible parts. The proposed model has been experimentally illustrated to predict the cutting stability and forced vibration on a table-tilting five-axis CNC machine tool.

We propose a new systematic matrix approach, which is an alternative to the disordered virtual ground technique, the Kirchhoff's law， and traditional Thevenin approaches, of designing the desired performance and simultaneously finding two Thevenin equivalent parameters for general complicated operational amplifier systems. One cannot apply the virtual ground method to non-ideal and partially ideal operational amplifier systems including instrumentation and frequency sensors. There has been no matrix method for efficiently solving a complicated operational amplifier circuit for conventional tedious approaches that apply Kirchhoff's law. We also propose a new method of finding Thevenin equivalent circuits for general complicated operational amplifier systems that has significant merits over traditional approaches including the open-circuit voltage and short-circuit current methods, the matrix node voltage (mesh current) method, the modified nodal (mesh) analysis, the reference node r model, the reflected impedance method, and the virtual ground method. To compare the proposed and traditional approaches, one demonstrated example and one comparative example are chosen. Moreover, we report a Bessel low-pass filter that is mainly made up of an AD8618 quad op-amp. Its transfer function for existing methods is incorrect in the non-ideal case, and thus the important amplitude-frequency and phase-frequency characteristic curves will not be exact. An online electrocardiograph (ECG) device is an important tool for many industrial medicine applications and is investigated in this study to demonstrate the practical value of the proposed results.

In controlled-source electromagnetic (CSEM) inversion with conventional regularization, the reconstructed conductivity image is usually blurry and only has limited resolution. To effectively obtain more compact conductivity models, we apply the concept of multinary transformation to CSEM inversion based on the finite element (FE) method with unstructured tetrahedral mesh. Within the framework of multinary inversion, the model conductivities are only allowed to be clustered within the designed values which is usually obtained from other a priori information or the conventional inversion. The synthetic studies show that the multinary inversion produces conductivity images with clearer model boundaries comparing to both the maximum smoothness inversion and the focusing inversion for realistic geoelectric models. We further applied the developed method to a land CSEM survey for mineral exploration. The multinary inversion results are closer to the ground truth comparing to the conventional maximum smoothness inversion and the focusing inversion. The developed method and numerical algorithm provide a new approach and workflow for CSEM inversion when the models need to have clear boundaries and clustering model values. Such geoelectric models could be very useful for geological interpretation in oil and mineral exploration when the a priori information (such as the estimated conductivity values) of the exploration targets is known.