Evaluation of a dual-T-type converter supplying an open-end winding induction machine

The multilevel inverter is a promising technology compared to two-level inverters in the applications of ac-drives and smart-grid applications. In this paper, a dual-T-type three-level inverters is used to drive an open-end winding induction machine. The Space-Vector Pulse-Width Modulation is selected as a good-performing control strategy to control the dual-inverter. Furthermore, an optimized method is used to select the proper switching state for the new configuration to decrease the converter losses. A comparison between the proposed configuration and the conventional diode clamped converter is made. The proposed drive system is designed and modelled by using Matlab/Simulink. It is shown that the converter can give the same hexagon, wave forms and harmonic spectrum of the five level converter. An optimized switching state selection is used to reduce the converter losses. The advantages and drawbacks of the dual-T-type configuration are discussed. In addition, the harmonic analysis and the loss calculations of the dual-T-type converter are provided and compared to the T-type three-level converter and the conventional five-level diode-clamped-converter

Preoperative predictive parameters for accurate detection of stage IV endometriosis

Abstract Background Surgery is the main line of treatment of endometriosis. Patients with stage IV endometriosis have more extensive adhesions, which make the surgery difficult. There are no accurate non-invasive predictive preoperative parameters of stage IV endometriosis and no consensus has been reached. Therefore, the aim of the present study was to evaluate and detect preoperative non-invasive parameters for the detection of stage IV endometriosis. Patients and methods In the present study, we included 150 females admitted for surgical removal of endometriosis. We scored and classified endometriosis into four stages according to the revised ASRM classification. We compared between baseline characteristics of patients with different stages of endometriosis, and then we selected the best combination of diagnostic and predictive parameters of stage IV endometriosis. Results Predictors of stage IV endometriosis and indicators for safety surgery were as follows: VAS ≥ 4 (p < 0.001), fixed uterus (p = 0.005), fixed ovarian cysts (p < 0.001), tender uterosacral ligament nodule (p < 0.001), tender rectovaginal septum nodule (p = 0.003), bilateral endometriosis (p < 0.001), and sum of sizes of endometriotic nodules (p < 0.001). Conclusion Fixed uterus, fixed ovarian cysts, tender uterosacral ligament nodule, tender rectovaginal septum nodule, bilateral endometriosis, and indications for surgery were significantly considered adequate predictive markers for stage IV endometriosis

System-Based Approaches for Structural Optimization of Flexible Mechanisms

peer reviewedThis paper reviews the state-of-the-art methods to perform structural optimization of flexible mechanisms. These methods are based on a system-based approach, i.e. the formulation of the design problem incorporates the time response of the mechanism that is obtained from a dynamic simulation of the flexible multibody system. The system-based approach aims at considering as precisely as possible the effects of nonlinear dynamic loading under various operating conditions. Also, the optimization process enhances most existing studies which are limited to (quasi-) static or frequency domain loading conditions. This paper briefly introduces flexible multibody system dynamics and structural optimization techniques. Afterwards, the two main methods, named the weakly and the fully coupled methods, that couple both disciplines are presented in details and the influence of the multibody system formalism is analyzed. The advantages and drawbacks of both methods are discussed and future possible research areas are mentioned