http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Morimoto Keiki,Ahmed Nabil A.,Lee Hyun-Woo,Nakaoka Mutsuo The Korean Institute of Electrical Engineers 2006 Journal of Electrical Engineering & Technology Vol.1 No.2
This paper presents a new circuit topology of DC busline switch and snubbing capacitor-assisted full-bridge soft-switching PWM inverter type DC-DC power converter with a high frequency link for low voltage large current applications as DC feeding systems, telecommunication power plants, automotive DC bus converters, plasma generator, electro plating plants, fuel cell interfaced power conditioner and arc welding power supplies. The proposed power converter circuit is based upon a voltage source-fed H type full-bridge high frequency PWM inverter with a high frequency transformer link. The conventional type high frequency inverter circuit is modified by adding a single power semiconductor switching device in series with DC rail and snubbing lossless capacitor in parallel with the inverter bridge legs. All the active power switches in the full-bridge inverter arms and DC busline can achieve ZVS/ZVT turn-off and ZCS turn-on commutation operation. Therefore, the total switching losses at turn-off and turn-on switching transitions of these power semiconductor devices can be reduced even in the high switching frequency bands ranging from 20 kHz to 100 kHz. The switching frequency of this DC-DC power converter using IGBT power modules is selected to be 60 kHz. It is proved experimentally by the power loss analysis that the more the switching frequency increases, the more the proposed DC-DC converter can achieve high performance, lighter in weight, lower power losses and miniaturization in size as compared to the conventional hard switching one. The principle of operation, operation modes, practical and inherent effectiveness of this novel DC-DC power converter topology is proved for a low voltage and large current DC-DC power supplies of arc welder applications in industry.
Keiki Morimoto,Nabil A. Ahmed,Hyun-Woo Lee,Mutsuo Nakaoka 대한전기학회 2006 Journal of Electrical Engineering & Technology Vol.1 No.2
This paper presents a new circuit topology of DC busline switch and snubbing capacitor-assisted full-bridge soft-switching PWM inverter type DC-DC power converter with a high frequency link for low voltage large current applications as DC feeding systems, telecommunication power plants, automotive DC bus converters, plasma generator, electro plating plants, fuel cell interfaced power conditioner and arc welding power supplies. The proposed power converter circuit is based upon a voltage source-fed H type full-bridge high frequency PWM inverter with a high frequency transformer link. The conventional type high frequency inverter circuit is modified by adding a single power semiconductor switching device in series with DC rail and snubbing lossless capacitor in parallel with the inverter bridge legs. All the active power switches in the full-bridge inverter arms and DC busline can achieve ZVS/ZVT tum-off and ZCS turn-on commutation operation. Therefore, the total switching losses at turn-off and turn-on switching transitions of these power semiconductor devices can be reduced even in the high switching frequency bands ranging from 20 ㎑ to 100 ㎑. The switching frequency of this DC-DC power converter using IGBT power modules is selected to be 60 ㎑. It is proved experimentally by the power loss analysis that the more the switching frequency increases, the more the proposed DC-DC converter can achieve high performance, lighter in weight, lower power losses and miniaturization in size as compared to the conventional hard switching one. The principle of operation, operation modes, practical and inherent effectiveness of this novel DC-DC power converter topology is proved for a low voltage and large current DC-DC power supplies of arc welder applications in industry.
Murad Q. A. Al-Gunaid,Shashikala B. S.,Gayitri H. M.,Khaled Alkanad,Nabil Al-Zaqri,Ahmed Boshaala,Fares H. Al-Ostoot 한국고분자학회 2022 Macromolecular Research Vol.30 No.9
A new series of flexible nanocomposite-solid polymer electrolyte (SPEs) in the form of poly(vinyl alcohol) (PVA) impregnated by core-shells polyaniline (PANI)-La2CuO4 (20:2 wt%) of nanofillers, 10wt% LiClO4 as electrolyte and various amount 2, 4, 6, and 8wt% of propylene carbonate, PC as plasticizer via solvent intercalation method. The obtained plasticized PVA-SPEs films were evaluated for their microstructural and morphological behaviors via X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy, respectively. The surface morphology of plasticized PVA-SPEs films illustrated the finer dispersion of inclusion fillers in the PVA matrix with increasing the dosage of PC content. FTIR spectra showed a reduction in the characteristic peaks of PVA in composite films and that denoted the interaction between PVA-OH and fillers. Optical findings exhibited higher absorbance of PVA-SPE in the visible region compared with pure PVA; in addition, the band-gap energy was reduced to 2.68 eV for PVA-SPE containing 8wt% PC. The current-voltage characteristics showed a slight deviation for all PVA-SPE films denoting to non-ohmic behavior. Besides, the maximum ac-conductivity was found at 40.3 × 10−5 S/cm for PVA-SPE film containing 8wt% PC with enhanced their specific capacitance by two folds compared with pure PVA. Mechanical testing showed that elongation at break has been increased attributed to increasing flexibility of polymeric segments with the increase in PC content.
NON CONVENTIONAL METHOD FOR SOFT STARTING OF THREE PHASE INDUCTION MOTORS
Nabil A. Ahmed,Sung-Jun Kim,Ki-Young Suh,Soon-Kurl Kown,Hyun-Woo Lee 전력전자학회 2004 전력전자학술대회 논문집 Vol.- No.-
This paper presents a nonconventional method for soft starting of three-phase induction motors, which achieved by flux weakening technique. Flux weakening is not done by reducing the applied voltage as in the conventional methods. Flux weakening is achieved by increasing the supply frequency over the rated value while the voltage amplitude is kept constant. This method has advantage of reducing the stress on the electrical and mechanical systems. The feasibility of this basic idea has been confirmed through investigating the starting transient corresponding to this mode of operation. For this purpose, a rigorous state space mathematical model has been developed and simulated. The validity of the proposed method through the results from the mathematical model have been confirmed experimentally.
SYNCHRONISATION OF HIGH PERFORMANCE RELUCTANCE MOTORS BY INCREASING THE SUPPLY FREQUENCY
Nabil. A.Ahmed,Mutsuo Nakaoka,Hyun Woo Lee 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
This paper presents a new technique for starting a high performance reluctance motors which cannot pull into step at normal operating condition. The proposed technique based on starting of the reluctance motor al frequency higher than the normal frequency.<br/> At the instant that the rotor speed reaches the synchronous speed of normal frequency. The main aim of the paper is starting and pulling into step of reluctance motor while keeping the desired performance without changing the motor parameter and design.
Working Capital Management and Banks’ Performance: Evidence from India
Nabil Ahmed Mareai SENAN,Suhaib ANAGREH,Borhan Omar Ahmad AL-DALAIEN,Fatehi ALMUGARI,Amgad S,D,KHALED,Eissa A,AL-HOMAIDI 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.6
The purpose of this study is to examine how Indian commercial banks’ performance can be improved by determinants of working capital management. This study uses both static models Generalised Moments Method (GMM) and pooled, fixed, and random-effects. The study is based on balanced panel data for 98 Indian banks from 2008 to 2018. Performance is defined by two indicators, namely, return on assets (ROA) and return on equity (ROE). While, working capital cycle, profit after tax, assets size, financial leverage, quick ratio, current ratio, return on capital employed, return on total assets, net profit margin, and monetary policy rate are used as independent variables. The results showed that net profit margin, profit after tax, monetary policy, and working capital cycle are the most important working capital factors that influence Indian commercial banks’ performance measured by (ROA). Moreover, among the working capital, the results showed that current ratio, assets size, net profit margin ratio, and return on capital employees have significant positive effects on (ROE). The article’s novelty and importance come from its recommendation that policymakers in emerging markets should motivate and enable managers and stakeholders to pay more attention to working capital by raising consumer awareness and increasing knowledge disclosure.
Nabil A. Ibrahim,Ahmed Amr,Basma M. Eid 한국섬유공학회 2020 Fibers and polymers Vol.21 No.3
Development of multifunctional cellulose-containing fabrics has been highly demanded both by the textile finisherand the textile consumer. Herein, proper finishing formulations comprise the following ingredients individually and incombination: a reactant crosslinker (Fixapret® ECO), hydrolysed 3-glycidyl-oxypropyltrimethoxysilane (GPTMS), as a cocrosslinkerand fixing agent, a flurochemical water/oil repellent agent (Asahi Guard® AG-925), silver nanoparticlesdispersion (AgNPs), as antibacterial agent along with metal salt catalyst, especially AlCl3, were applied to various cellulosecontaining fabrics, using a pad-coating impregnation method, to add new multifunctional properties like anti-crease, water/oilrepellent, antibacterial functionality as well as thermal stability. The degree of improvement in the imparted functions isgoverned by type of substrate, extent of modification and/or crosslinking, amount/location/distribution as well as fixation ofthe added active ingredients. Also, the obtained results clearly demonstrated that the created multifunctional properties arenot seriously decreased even after 15 washing cycles. Various characterization techniques were used, and the possibleinteractions among the nominated components and the treated substrates were also suggested.