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23 results on '"Kazemi, H."'

12. PMU-based distribution network load modelling using Harmony Search Algorithm.

Author

Alinejad, B., Akbari, M., and Kazemi, H.

Abstract

In this paper a new technique for estimation of distribution network load model parameters based on PMU measurements data and Harmony Search Algorithm (HSA) is proposed. Distribution network loads reveal some complicated behavior as these networks are connected to distributed generations (DG) such as fuel cells or wind turbines which implements modern electrical machines. Therefore, the conventional models of the distribution loads should be modified to overcome this problem. Estimated model not only should have a same response to real model in the normal condition of the network, but also must be valid under network faults and transient conditions. In this paper the load model and its relative equations has been modified. Estimation of the double fed induction machine (DFIM) parameters and load power-dependability to network frequency change are included in the model. The proposed model is simulated in Matlab/Simulink software under some normal and abnormal conditions of the network. The results show the efficiency and capability of the algorithm. [ABSTRACT FROM PUBLISHER]

Published
2012

17. Advances in schottky rectifier performance.

Author

Brown, E.R., Young, A.C., Zimmerman, J., Kazemi, H., and Gossard, A.C.

Abstract

In conclusion, heteroepitaxial technology has delivered a new device building block for the microwave and millimeter-wave toolbox - a single-crystal Schottky barrier diode made from a lattice matched combination of a semimetal (ErAs) and a semiconductor (InAlGaAs). This article has demonstrated how sensitive such a Schottky diode can be as a room-temperature zero-bias rectifier up to W band and addressed the fundamental device and impedance matching issues when coupled to a planar antenna in a quasi-optical package. As might be expected, the new Schottky diodes also display a very low degree of 1/f noise when used in applications that require bias or large signals, such as frequency mixers and multipliers (Young et al., 2006) [ABSTRACT FROM PUBLISHER]

Published
2007
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18. Two-Dimensional Millimeter Wave Phase Scanned Lens Utilizing Analog Electromagnetic Crystal (EMXT) Waveguide Phase Shifters.

Author

Hao Xin, West, James B., Mather, John C., Doane, J. P., Higgins, J. Aiden, Kazemi, H., and Rosker, Mark J.

Subjects
WAVEGUIDES, ELECTRONIC equipment, ELECTRIC waves, RADIO technology equipment, ELECTRICAL conductors, PHYSICAL measurements
Abstract

A novel type of waveguide phase shifter utilizing tunable electromagnetic crystal (EMXT) surfaces is incorporated in a 16-element two-dimensional (2-D) millimeter wave (38 GHz) phase-scanned lens. EMXT surfaces integrating semiconductor varactors are used as the sidewalls of a waveguide to provide a tunable impedance boundary for the waveguide. The EMXT waveguides are used as 360° analog phase shifters as well as radiating elements to realize electronic beam scanning with microseconds of response time. The four-by-four array achieved +/- 30° of beam scanning in both the E and H planes. The electrical and mechanical design, top-level array calibration, and scan performance of the 16-element proof-of-concept 2-D space fed phased array lens are described. The waveguide phase shifter insertion loss performance and plans for further improving insertion loss are discussed. The average insertion loss is expected to be less than 2.0 dB at an operating frequency of 38 GHz for GaAs substrate-based EMXT surfaces with planar Schottky diode tuning elements. This new type of EMXT waveguide array may provide a low-cost and high performance alternative to a conventional phased array. [ABSTRACT FROM AUTHOR]

Published
2005
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