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| 1 | A novel control strategy for load converter of DC isolated distribution system under unbalanced loading conditions显示文摘A novel control strategy for the load converter supplying the unbalanced AC load in a DC isolated distribution system is presented. The control algorithm results in balanced and sinusoidal load voltages under unbalanced AC loading. The unbalanced load is characterized in the d-q-0 rotating coordinate based on symmetrical sequence components. Also, the mathematical model of the load converter in both a-b-c and d-q-0 coordinates is derived by using the average large signal model. Then, two control strategies for the load converter are presented. The first one uses the conventional d-q-0 controller to ensure the voltage and current regulation. The second one is a newly proposed control strategy based on the decomposition of the voltage and current into in-stantaneous positive, negative, and zero sequences. These three sequences are controlled independently in their own reference frames as DC signals. The performance of the load converter using these two control strategies is compared. Simulation results show the validity and capability of the newly proposed control strategy. | R.NOROOZIAN M.ABEDI G.B.GHAREHPETIAN S.H.HOSSEINI | 2009 | Journal of Zhejiang University-Science A(Applied Physics & Engineering)2009，10，6： | 1 |
| 2 | Axisymmetric and three-dimensional flow simulation of a mixed compression supersonic air inlet显示文摘The flow through an axisymmetric supersonic mixed-compression air inlet has been simulated numerically to investigate the effects and the necessity of the three-dimensional(3D)modeling in comparison with the axisymmetric one.For this purpose,a supersonic inlet has been simulated numerically via axisymmetric and 3D CFD solvers,using the steady state Reynolds-averaged Navier-Stokes equations along with the SST k-ωturbulence model,for a free-stream Mach number of 2.0 and at zero degrees angle of attack.The grid for the 3D cases was a 14.4-degree sector,instead of a 360-degree domain one,with rotational periodic boundary condition for the side boundaries.The results show that both static and total pressure distributions match well with the experimental data for both the axisymmetric and the 3D simulations.If the prediction of performance parameters is the main goal of simulations,it seems that the axisymmetric simulation provides adequate accuracy,and the 3D simulation one is not the best choice.The 3D numerical simulation results in an in-depth study on the supersonic inlets,including the shock wave-boundary layer interaction,the location of the terminal normal shock wave,and consequently the separation point.For an axisymmetric supersonic inlet in an axisymmetric flow condition,3D effects are not strong enough to have a significant influence on the inlet performance for all operational conditions.However,it seems that 3D effects play an important role in both critical and supercritical operating conditions during the steady state operation. | M.Abedi R.Askari J.Sepahi-Younsi M.R.Soltani | 2020 | Propulsion and Power Research2020，9，1： | 1 |
| 3 | Determination of arsenic in air particulates and diesel exhaust particulates by spectrophotometry显示文摘A method was developed for the determination of trace arsenic by spectrophotometry. The proposed method is rapid, simple, and inexpensive. This method can be used for sensitive determination of trace arsenic in environmental samples and especially in air particulates. The results obtained by this method as a proposed method were compared with those obtained by hydride generation atomic absorption spectrometry as a popular reported method for the determination of arsenic and an excellent agreement was found between them. The method was also used for determination of arsenic associated with airborne particulate matter and diesel exhaust particulates. The results showed that considerable amount of arsenic are associated with diesel engine particulates. The variation in concentration of arsenic was also investigated. The atmospheric concentration of arsenic was different in different sampling stations was dependent to the traffic density. | S.M.Talebi M.Abedi | 2005 | Journal of Environmental Sciences2005，17，1： | 0 |
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