This paper presents an artificial neural network (ANN) based fault diagnosis system (FDS) for tapped power transmission lines. The proposed system is designed to detect the fault, localize the faulted zone, classify the fault type and finally identify the faulted phase. The FDS consists of three hierarchical levels. In the first level, a preprocessing to input data is performed. An ANN, in the second level, is designed to detect the fault and localize the faulted zone. In the third level, two zone diagnosis systems (ZDS) are designed. Each ZDS is dedicated to one zone and consists of four-parallel ANN's in order to achieve the fault type classification. Each one of the paralleled ANN’s, except the last one, is cascaded with another ANN designed mainly for the selection of the faulted phase.

This paper deals with diagnosis of induction motor broken bar fault supplied from a special variable speed drive (VSD) equipped with an AC reactor and a sine-wave shaping filter on the output side, which could not be avoided due to vibration limits of the supporting construction. the proposed method is the instantaneous power spectrum analysis technique combined with the mean absolute difference (MAD) approach. The experimental results show that the instantaneous power spectrum analysis method is only effective when the motor is supplied from a sinusoidal supply, in contrast to the demonstrated VSD. The instantaneous power spectrums of the healthy rotor case and the broken bar rotor cases is processed with MAD algorithm to investigate the similarity between them. The results show that this combined technique is highly effective in diagnosis of broken rotor bar fault in case of the special VSD.

This paper presents a theoretical elastic buckling analysis of steel rectangular plates with stiffened or unstiffened openings. The plate is subjected to in-plane combined linearly varying compressive and shearing edge stresses. In this analysis, the plate is assumed simply supported along all edges. The location and thesize of the opening, the stiffeners position and the cross section area of the stiffeners are the main parameters studied. Moreover, the compressive stress gradient (ψ) and the ratio of applied normal and shear stresses on the plate edges are taken into account. The minimum potential energy technique is used to analyze and solve the general mathematical formulations of the plate buckling under the aforesaid situation.Explicit equations as well as simplified ones are derived from which the buckling load of the plate can be obtained. The present predictions of the analysis are shown to be in a good agreement with the theoretical and experimental previous studies available. The predicted equations, graphs and the computer program are found to be more rational, accurate and versatile for design engineers.

A high performance motor drive requires fast step-tracking response with acceptable overshoot, minimum speed-dip and restore-time following a step load change, and zero steady-state error in the command tracking and load regulation. In this paper, a comparative study is carried out between two output-feedback control techniques to achieve a high performance induction motor. The first, named Discrete-Time Dynamic Programming (DTDP) output feedback, uses historical data from the controlled inputs and outputs of the motor and an optimization technique, dynamic programming algorithm, to obtain an optimum design of the needed constant output feedback gain matrix. In the last, named Linear Matrix Inequalities (LMI) output-feedback, the reduction of the disturbance on the motor speed is done through the minimization of the Hinfinity (H) norm using Linear Matrix Inequality. The design procedure is based on the linearization of the motor nonlinear current-model around a selected operating point. The system performance of the motor equipped with DTDP and LMI controllers is analyzed using diverse tests namely, load disturbance (regulation and tracking) and parameters variation. For completeness, the performance of a conventional ProportionalIntegral (PI) controller are also included for comparison purposes. The results are very encouraging to pursue further this study.

In this paper, we are concerned with the performance of the quantum cascaded lasers (QCLs) under two different cases, pulsed and continuous wave (PW, CW) operations. The dependence of PW and CW on QCLs parameters is declared. These parameters are width of the strip, number of stages and wavelengths. Also, proposed relations that link emitted power, threshold current, and slope efficiency with QCLs parameters are deduced. To verify the validity of these theoretical equations, comparison studies with experimental results are done. From comparison of the theoretical and experimental characteristic behaviors, the considered equations give satisfactory results. Furthermore, mathematical approximation for the maximum and minimum values of the output optical power is deduced.