Effects of Zero-Sequence Transformations and Min-Max Injection on Fault-Tolerant Symmetrical Six-Phase Drives with Single Isolated Neutral

Munim, Wan Noraishah Wan Abdul,Tousizadeh, Mahdi,Che, Hang Seng The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4

Recently, there has been increased interest in the study of multiphase machines due to their higher fault-tolerant capability when compared to their conventional three-phase counterparts. For six-phase machines, stator windings configured with a single isolated neutral (1N) provide significantly more post-fault torque/power than two isolated neutrals (2N). Hence, this configuration is preferred in applications where post-fault performance is critical. It is well known that min-max injection has been commonly used for three-phase and multiphase machines in healthy condition to maximize the modulation limit. However, there is a lack of discussion on min-max injection for post-fault condition. Furthermore, the effects in terms of the common-mode voltage (CMV) in modulating signals has not been discussed. This paper investigates the effect of min-max injection in post fault-tolerant control on the voltage and speed limit of a symmetrical six-phase induction machine with single isolated neutral. It is shown that the min-max injection can minimize the amplitude of reference voltage, which maximizes the modulation index and post-fault speed of the machine. This in turn results in a higher post-fault power.

Forecasting container throughput of major Asian ports using the Prophet and hybrid time series models

Munim Ziaul Haque,Fiskin Cemile Solak,Nepal Bikram,Chowdhury Mohammed Mojahid Hossain 한국해운물류학회 2023 The Asian journal of shipping and Logistics Vol.39 No.2

Forecasting container throughput is critical for improved port planning, operations, and investment strategies. Reliability of forecasting methods need to be ensured before utilizing their outcomes in decision making. This study compares forecasting performances of various time series methods, namely autoregressive integrated moving average (ARIMA), seasonal ARIMA (SARIMA), Holt-Winter's Exponential Smoothing (HWES), and the Prophet model. Since forecast combinations can improve performance, simple and weighted combinations of ARIMA, SARIMA and HWES have been explored, too. Monthly container throughput data of port of Shanghai, Busan, and Nagoya are used. The Prophet model outperforms others in the in-sample forecasting, while combined models outperform others in the out-sample forecasting. Due to the observed differences between the in-sample and out-sample forecast accuracy measures, this study proposes a forecast performance metric consistency check approach for informed real-world applications of forecasting models in port management decision-making.

COVID-19 and the Health of Banking Sector in Japan and South Korea: A Comparative Study

( Munim Kumar Barai ) 대외경제정책연구원 2020 Working Papers Vol.22 No.1

Does higher technical efficiency induce a higher service level? A paradox association in the context of port operations

Ziaul Haque Munim 한국해운물류학회 2020 The Asian journal of shipping and Logistics Vol.36 No.4

Researchers and practitioners are benchmarking technical efficiency of ports and exploring the drivers of high efficiency. Paradoxically, this study argues that high technical efficiency (TE = 1) is not always essential, but an optimal level needs to be achieved while balancing the port service level. This study applies data envelopment analysis (DEA) and free disposal hull (FDH) methods to perform efficiency rankings of 38 container terminals from 17 different ports in 12 Asian countries. Four terminals are technically efficient (TE = 1) in all frontier approaches, thereof one Bangladeshi, one Chinese, one Indian and one Vietnamese. Furthermore, this study presents a case study combining qualitative and quantitative data analysis to investigate the characteristics of a port hosting high technically efficient container terminals The finding suggests that ports with growing throughput, not investing actively in infrastructure and equipment, become high technically efficient over time, but the higher their technical efficiency, the lower their service level

Effects of Zero-Sequence Transformations and Min-Max Injection on Fault-Tolerant Symmetrical Six-Phase Drives with Single Isolated Neutral

Wan Noraishah Wan Abdul Munim,Mahdi Tousizadeh,Hang Seng Che 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4

Recently, there has been increased interest in the study of multiphase machines due to their higher fault-tolerant capabilitywhen compared to their conventional three-phase counterparts. For six-phase machines, stator windings configured with a singleisolated neutral (1N) provide significantly more post-fault torque/power than two isolated neutrals (2N). Hence, this configuration ispreferred in applications where post-fault performance is critical. It is well known that min-max injection has been commonlyused for three-phase and multiphase machines in healthy condition to maximize the modulation limit. However, there is a lack ofdiscussion on min-max injection for post-fault condition. Furthermore, the effects in terms of the common-mode voltage (CMV)in modulating signals has not been discussed. This paper investigates the effect of min-max injection in post fault-tolerant controlon the voltage and speed limit of a symmetrical six-phase induction machine with single isolated neutral. It is shown that themin-max injection can minimize the amplitude of reference voltage, which maximizes the modulation index and post-fault speedof the machine. This in turn results in a higher post-fault power.

Chitosan Mediated Formation and Impregnation of Silver Nanoparticles on Viscose Fabric in Single Bath for Antibacterial Performance

Zulfiqar Ali Raza,Umaira Bilal,Unsa Noreen,Somayyah Abdul Munim,Shahina Riaz,Muhammad Umar Abdullah,Sharjeel Abid 한국섬유공학회 2019 Fibers and polymers Vol.20 No.7

Cellulosic materials being biodegradable are susceptible to bacterial attack. Present study was meant to develop anantibacterial viscose fabric via a clean, easy and reproducible approach. Silver nanoparticles (SNPs) were prepared usingchitosan both as reducing and as well as stabilizing agent to promote green synthesis of SNPs. The prepared SNPs werecharacterized using dynamic light scattering and UV-visible (vis) absorption spectroscopy. The average size of SNPs wasfound to be 8.574 nm with respective zeta potential of +45.2 mV using AgNO3 concentration of 1 mM and chitosan as 1 %(w/v). Pre-treated viscose fabric was undergone an in situ treatment to impregnate SNPs on its surface under certain autoclaveconditions. Scanning electron microscopy revealed the presence of SNPs on surface of treated viscose fabric in comparisonwith the untreated fabric. In addition, Fourier transform infrared and elemental analysis confirmed the presence of silver onthe treated fabric. The textile properties of the viscose fabric samples like; tensile strength, wettability, antibacterial activityand whiteness were evaluated using the standard protocols. The developed treated viscose fabric showed good antibacterialproperties against both Gram negative Escherichia coli and Gram-positive Staphylococcus aureus bacterial strains with fairtextile characteristics. This is the first report on in situ fabrication and impregnation of SNPs using chitosan as both reducingand stabilizing agent on a regenerated cellulose fabric like viscose.

Management of Psoriasis through Unani Medicine: a Case Study

Khatoon, Faiza,Uddin, Qamar,Jabeen, Arzeena,Azahar, Mohd,Alam, Md Aftab,Munim, Abdul Cellmed Orthocellular Medicine and Pharmaceutical 2021 셀메드 (CellMed) Vol.11 No.2

Psoriasis is a chronic inflammatory skin disease clinically characterized by erythematous, sharply demarcated papules and rounded plaques covered by silvery white micaceous scales. It affects about 1-3% of the world's population. Although considerable advances have been made in the management of psoriasis in recent years, the disease remains incurable. Current treatment does not affect disease activity, and relapse occurs quickly after cessation of treatment. Moreover, topical and systemic conventional therapies used in the management of psoriasis are associated with adverse effects. In Unani system of medicine, psoriasis is known as Taqashshur al-Jild, which is caused by predominance of black bile and characterised by scaling of skin. Various topical as well as systemic Unani formulations are effectively used in the management of psoriasis. This case study was aimed to evaluate the efficacy of Unani formulations, Itrīfal Shāhtra and Marham Ḥinā in the management of psoriasis. A 49-year-old male patient presenting with psoriasis came to the OPD of National Research Institute of Unani Medicine for Skin Disorders, Hyderabad. Treatment was given to the patient for a period of 12 weeks. PASI score was significantly reduced from 40.5 at baseline to 2.2 after treatment. Unani formulations were found safe and effective in the management of Psoriasis as assessed by validated scales.