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This paper presents a novel technique for the analysis of looped linear time-invariant electric circuits. This approach works in both time and Laplace domains; any type of elements could hence be incorporated. The circuit elements are partitioned into twofold classes of basic circuit and subsidiaries. The basic circuit is a spanning tree of the network, and the subsidiaries include circuit elements hypothetically removed from the looped electric circuit to open the loops. The subsidiaries include a suit of passive elements which might not even make any interconnected circuit. The circuit governing equations of flow and energy conservation are manipulated so that branch currents in the subsidiaries and branch voltages in the basic circuit are considered as independent variables to calculate passive element properties (impedance of all passive elements) directly. In contrast to existing methods, this technique is tailored for the circuit analysis in a reverse manner. As a complement for conventional circuit analysis techniques, this method can be taught in the undergraduate program to offer the students an alternative tool for the circuit analysis.

The aim of this paper is to establish an approach to quantitatively determine the elasto-plastic parameters of the Mo-modified Ti obtained by the plasma surface alloying technique. A micro-indentation test is conducted on the surface under 10N. Considering size effects, nanoindentation tests are conducted on the cross-section with two loads of 6 and 8mN. Assuming nanoindentation testing sublayers are homogeneous, finite element reverse analysis is adopted to determine their plastic parameters. According to the gradient distributions of the elasto-plastic parameters with depth in the Mo-modified Ti, two types of mathematical expressions are proposed. Compared with the polynomial expression, the linear simplified expression does not need the graded material to be sectioned and has practical utility in the surface treatment industry. The validation of the linear simplified expression is verified by the micro-indentation test and corresponding finite element forward analysis. This approach can assist in improving the surface treatment process of the Mo-modified Ti and further enhancing its load capacity and wear resistance.

In this paper, the effect of the process parameters such as laser power, shielding gas flow and scanning velocity on the actual laser power reaching the surface and thermal efficiency is investigated. For this purpose, the response surface methodology was used to investigate the effect of the process parameters at three levels. In order to measure the data from a 316L stainless steel, four k-type thermocouples are installed in different positions relative to the motion of the laser beam. The actual power was calculated by reverse analysis using the simulated annealing technique and the temperature history was measured by the thermocouples. The thermal model used is an optimized Rosenthal model, which is considered variable with temperature. The results show that for all thermocouples, the highest values of actual power that reached the surface were obtained at laser power of 200W, scanning velocity of 2mm/s and shielding gas flow of 30Lit/min. In addition, by increasing the laser power from 100 to 200W, the thermal efficiency decreases by about 4% to 12%. The thermal efficiency also decreases by about 8%, when the scanning velocity increased from 1 to 3mm/s. Moreover, the increase of the shielding gas flow from 25 to 35Lit/min initially improved the thermal efficiency and then decreased it. The models obtained from the analysis of variance in the heating cycle are in good agreement with the experimental results, but in the cooling cycle, the accuracy of this model decreases.

This paper reviews various techniques to characterize material by interpreting load-displacement data from instrumented indentation tests. Scaling and dimensionless analysis was used to generalize the universal relationships between the characteristics of indentation curves and their material properties. The dimensionless functions were numerically calibrated via extensive finite element analysis. The interpretation of load-displacement curves from the established relationships was thus carried out by either solving higher order functions iteratively or employing neural networks. In this study, the advantages and disadvantages of these techniques are highlighted. Several issues in an instrumented indentation test such as friction, size effect and uniqueness of reverse analysis algorithms are discussed. In this study, a new reverse algorithm via neural network models to extract the mechanical properties by dual Berkovich and spherical indentation tests is introduced. The predicted material properties based on the proposed neural network models agree well with the numerical input data.