We observe experimentally a novel type of nonlinear diffraction in the process of two-wave mixing on a nonlinear quadratic grating. We demonstrate that when the nonlinear grating is illuminated simultaneously by two noncollinear beams, a second-harmonic diffraction pattern is generated by a virtual beam propagating along the bisector of the two pump beams. The observed diffraction phenomena is ...

by minimizing the total potential energy function and deploying the virtual work principle, a higher-order stiffness matrix is achieved. this new tangent stiffness matrix is used to solve the frame with geometric nonlinear behavior. since authors’ formulation takes into account the higher-order terms of the strain vector, the convergence speed of the solution process will increase. in fact, bot...

active filters have proven to be more effective than passive techniques to improve power quality and to solve harmonic and power factor problems due to nonlinear loads. this paper proposes a control scheme based on the instantaneous active and reactive power. the inverter of this active filter is a three-phase, two-level converter. space vector technique is used as modulators and pattern genera...

This paper is concerned with the control of nonlinear pure-feedback systems with unknown nonlinear functions. This problem is considered di/cult to be dealt with in the control literature, mainly because that the triangular structure of pure-feedback systems has no a/ne appearance of the variables to be used as virtual controls. To overcome this di/culty, implicit function theorem is 0rstly exp...

The purpose of this study was to investigate consistency of performance of robot-assisted surgical tasks in a virtual reality environment. Eight subjects performed two surgical tasks, bimanual carrying and needle passing, with both the da Vinci surgical robot and a virtual reality equivalent environment. Nonlinear analysis was utilized to evaluate consistency of performance by calculating the r...

In this study, we propose a nonlinear model-following control for underactuated systems. A model-following control design is based on the virtual constrains. The concept of virtual constraints control proposed by Shiriaev et. al. The model-following control is useful to realize the tracking system to a given reference model. In underactuated systems, a modelfollowing control for fullactuated sy...

The variation of facial appearance due to the viewpoint or pose obviously degrades the accuracy of any face recognition systems. One solution is generating the virtual frontal view from any given non-frontal view to obtain a virtual gallery/probe face. As the state-of-the-art face recognition algorithm, linear regression computes a reconstruction matrix from the images of each subject and then ...

Abstract: The problem of virtual sensors design in linear and nonlinear systems is studied. problems solved three steps: at the first step, model invariant with respect to disturbance designed; second a possibility take into account term estimate given variable checked; finally, stability observer achieved. relations allowing sensor minimal dimension estimating prescribed component state vector...

Since the online measurement of melt index (MI) of polyethylene is difficult, a virtual sensor model is desirable. However, a polyethylene process usually produces products with multiple grades. The relations between process and quality variables are highly nonlinear. In addition, a virtual sensor model in the real plant process with many inputs has to deal with the collinearity and the time-va...

in this paper the nonlinear bending analysis of thick functionally graded plates subjected to mechanical loading is studied. the formulation is derived based on the third-order shear deformation plate theory and von kármán type non-linearity. young’s modulus is assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. the principle of virtual wo...