http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Bahgat, M.,Paek, Min-Kyu,Pak, Jong-Jin The Iron and Steel Institute of Japan 2008 ISIJ international Vol.48 No.11
<P>Nickel and Nickel cobalt ferrite powders were prepared through the ceramic route by calcination of a stoichiometric mixture of nickel oxide, cobalt oxide and mill scale as source for iron oxide. The produced ferrites powders were isothermally reduced in pure hydrogen at 800–1100°C. Based on thermogravimetric analysis, the reduction behavior of the synthesized ferrite and the kinetics reaction mechanism were studied. The initial ferrite powder and the various reduction products were characterized by XRD, SEM and reflected light microscope to reveal the effect of hydrogen reduction on composition, microstructure and reaction kinetics of synthesized ferro-alloys. The activation energy values were calculated from Arrhenius equation. The approved mathematical formulations for the gas solid reaction were applied to confirm the estimated rate controlling reaction mechanism. Complete reduction of home made ferrite powder was achieved with synthesize of nanocrystalline Fe–Ni and Fe–Ni–Co alloys.</P>
Micro-grid Monitoring and Supervision: Web-based SCADA Approach
Ali Mohamed A.,Barakat Mahmoud M.,Abokhalaf Masoud M.,Fadel Yasmin H.,Kandil Mohamed,Rasmy Mariam W.,Ali Osama N.,Besheer Ahmad H.,Emara Hassan M.,Bahgat Ahmed 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.5
Owing to the widespread use of the micro-grid concept to serve many real life applications, the main concern of this paper is to monitor, evaluate and manage the operational performance of an existent, already installed micro-grid that consists of On & Off grid PV systems in addition to the main grid supply. With the aid of customized web based SCADA system fully designed by authors, the performance evaluation of the proposed micro-grid is carried out in terms of energy consumption, power quality indices and energy cost based on Egypt’s energy current tariff . The designed system helps in both micro-grid status monitoring as well as load sharing between the main grid supply and the off grid PV energy system. The data of the on grid PV energy system are accessed and collected online directly from the inverter web server instead of downloading them offl ine from the PV inverter. In this case, data are analyzed with a reasonable refresh rate, which saves time and eff ort. Remote access platform is developed securely through a multi-level security authentication and strong data encryption using the OpenVPN protocol under the Dynamic Domain Name System service. Smart wired and wireless technology—used as integrated sensing devices to the developed SCADA system—enables easy system installation and running cost saving. Finally, to validate the collected data from the newly SCADA designed monitoring system, a performance characterization for the on grid PV system following international standards of yields calculations is carried out for 3 months in 2019.
Nonlinear Observers for Spacecraft Attitude Estimation in Case of Yaw Angle Measurement Absence
Mohamed M. Aly,Hossam A. Abdel Fatah,Ahmed Bahgat 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.5
This paper provides a brief presentation and a useful comparison between two nonlinear observers Extended Kalman Filter (EKF) and sliding mode observer (SMO). Both can be used for moderate-accuracy attitude determination systems for Low Earth Orbit (LEO) Earth-pointing spacecraft (s/c), which is typically achieved using Gyroscopes, Earth, and Sun sensors for attitude sensing. The use of these observers provides a substitute for the yaw data in case of the s/c eclipse periods or limited field of views. The nonlinear observability for this system is analytically investigated via the calculation of Lie derivatives to check the possibility of the system states estimation. The performances of both observers are presented, the SMO stability is proved and the SMO enhanced estimates are shown by simulation.