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Kaf Wafaa A.,Reiter Samantha,Brodeur Amanda,White-Minnis Letitia,Deal William 대한청각학회 2023 Journal of Audiology & Otology Vol.27 No.3
In this study, we report our findings of comprehensive evaluation in a man with syndromic craniofacial features, cognitive impairment, and hearing loss. The patient underwent psychological and genetic testing and screening for 133 genetic mutations associated with hearing loss, as well as extensive audiological evaluation to assess the auditory pathway between the middle ear and the auditory cortex. Psychological testing showed moderate cognitive impairment. Genetic testing did not reveal a genetic mutation for hearing loss. Audiological evaluation revealed mixed hearing loss and signs of auditory neuropathy spectrum disorder (ANSD) despite absence of otoacoustic emissions and an absent click-evoked auditory brainstem response (ABR) without recording of cochlear microphonics (CM). ANSD was characterized by abnormal speech discrimination, bilateral robust CM to 2,000 Hz tone-burst (TB) ABR, and abnormal left thalamocortical and cortical pathways diagnosed based on auditory middle latency and cortical N1-P2 responses. These behavioral and electrophysiological findings suggest post-synaptic ANSD at the brainstem level. An abnormal left thalamocortical auditory pathway may be attributable to the combined effect of lack of neural synchrony secondary to ANSD mainly on the left and/or brain injury. The findings in this study support the use of TB ABR and auditory cortical potentials in the ANSD test protocol and in patients with craniofacial anomalies.
Fault Detection of NPC Inverter Based on Ensemble Machine Learning Methods
Al-kaf Hasan Ali Gamal,Lee Jung-Won,Lee Kyo-Beum 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1
Three-level neutral point clamped (NPC) inverters have been widely adopted in diferent appliances, but their growing use leads to increased susceptibility to faults in the system. It is therefore essential to design precise and efcient methods that can detect inverter faults to ensure optimal control and prevent serious damage to the system. However, the most accurate fault diagnosis methods often require signifcant amounts of time to collect input data such as current and voltage images, or they involve lengthy data rows that are not commonly applicable to real-time applications. To compensate for these drawbacks, ensemble machine learning (EML) methods are proposed to detect open-circuit faults that only require one single point as an input. Moreover, the proposed methods were trained using DC-link voltage diference, time, and three phase currents to improve the accuracy of open-circuit fault detection. The feasibility and efectiveness of the proposed method are verifed through simulation and experimentation. The present work also presents a comprehensive comparison of EML methods. The results show that Random Forest (RF) and Bootstrap Aggregating (bagging) methods achieve high performance compared to other EML methods, with an accuracy of 97%, without requiring additional circuitry. Additionally, the results show that incorporating time and DC-link voltage diferences, along with three-phase current, improves the performance of EML methods.
Robust Hybrid Current Controller for Permanent-Magnet Synchronous Motors
Al-kaf Hasan Ali Gamal,Lee Kyo-Beum 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3
In recent years, hybrid models have been widely used for various power electronic appliances. The principal idea of hybrid model is to combine the merits of each control method to achieve better overall performance. However, switching between controllers remains a challenging problem that requires robust switching techniques to ensure smooth transition between controllers. Existing switching techniques tend to cause undesired bumps, oscillations, and large overshoots in the motor drives. Therefore, this study proposes a robust hybrid model that combines field-oriented control and model predictive control (MPC) using the cost function of MPC for permanent-magnet synchronous motors fed by a two-level inverter. In addition, space vector pulse width modulation is used to guarantee a constant switching frequency. The results show that the proposed hybrid model has fast dynamics, zero steady state error, small overshoot and constant switching frequency. In addition, the results reveal that the hybrid model provides good performance and outperforms conventional hybrid method in different operating cases. Simulation and experimental results demonstrate the effectiveness of the proposed hybrid model.
Fast Dynamic Field-Oriented Control Using Direct Large Voltage Vector and Hysteresis Switch
Hasan Ali Gamal Al-kaf,Kyo-Beum Lee 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-
Field-oriented control (FOC) has been widely used for controlling the current control of permanent magnet synchronous motors (PMSMs) due to its excellent performance in steady-state operation. FOC suffers from slow dynamic response, as a result, its practical use may be limited for applications that require a very fast dynamic response. Accordingly, in this paper, a fast dynamic FOC (FFOC) for PMSM based on a real voltage vector and hysteresis switch is proposed. The hysteresis switch uses FOC in steady-state and the direct real voltage vector in transient-state. Simulation results show that the proposed model has similar steady-state performance as FOC. In addition, FFOC shows faster dynamic performance when FOC and model predictive control (FOC-MPC) are combined using hysteresis switch.
Choi, M.,Kadara, H.,Zhang, J.,Parra, E.R.,Rodriguez-Canales, J.,Gaffney, S.G.,Zhao, Z.,Behrens, C.,Fujimoto, J.,Chow, C.,Kim, K.,Kalhor, N.,Moran, C.,Rimm, D.,Swisher, S.,Gibbons, D.L.,Heymach, J.,Kaf Elsevier 2017 Annals of oncology Vol.28 No.1
<P>Conclusion(s): Our findings pinpoint mutated genes that may impact clinical outcome as well as personalized strategies for targeted immunotherapies in early-stage LUSC.</P>