Performance analysis of real-time PSO tuned PI controller for regulating voltage and frequency in an AC microgrid

In this study, a control strategy based on the self-tuning method and synchronous reference frame (SRF) with PI regulator is proposed to achieve optimum quality of power in an autonomous micro grid (MG). The MGS is based on multiple distributed generation (DG) connected with 120 kV power grid. The proposed system is first simulated with fixed gain values for PI controller which are not optimal for sudden changes in the system i.e. transition of MG to islanding mode, load variations. So, the particle swarm optimization (PSO) has been utilized for tuning of PI controller parameters which ensure flexible performance and superior quality of power. The principal parameters considered in this study are, regulation of voltage and frequency, steady-state and dynamic response and harmonic distortion, mainly when microgrid is islanded. The performance of PI and PI-PSO is compared in this study by simulating AC microgrid in the MATLAB/Simulink environment. Summarized results of the system are provided to authenticate viability of proposed arrangement. The proposed controller performs intelligently while regulating voltage and frequency of the MGS and utility system.

Response to Letter to the Editor

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89557/1/j.1399-0012.2011.01437.x.pd

Stationary Black Holes with Static and Counterrotating Horizons

We show that rotating dyonic black holes with static and counterrotating horizon exist in Einstein-Maxwell-dilaton theory when the dilaton coupling constant exceeds the Kaluza-Klein value. The black holes with static horizon bifurcate from the static black holes. Their mass decreases with increasing angular momentum, their horizons are prolate.Comment: 4 pages, 6 figure

Factors associated with positive attitudes toward organ donation in Arab Americans

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86866/1/j.1399-0012.2010.01382.x.pd

Procaspase- 3 Status in Benign Prostatic Hyperplasia and Carcinoma (A Correlative Retrospective Study)

Background: Benign prostatic hyperplasia and prostatic adenocarcinoma are two of the most common pathologic mass lesions. Both are encountered mainly in elderly males. The caspases family is a group of at least 15 known proteases that serve as initiator & effector molecules of the apoptosis pathway. Caspase-3, in particular, is thought to play a pathogenetic role in both prostatic hyperplasia and carcinoma. Finasteride is a medication that has routinely been given to patients with hyperplasia and carcinoma; its prostate size-reducing effect is thought to be mediated through caspases. Patients and methods: fifty patients with prostatic mass lesions were included in this study (20 with hyperplasia & 30 with adenocarcinoma); all were on finasteride treatment. The carcinoma cases were graded according to Gleason scoring system. All cases were analyzed for procaspase-3 strength of staining. Results: benign hyperplasia & well-differentiated carcinomas show high expression of procaspase-3, in contrast loss of expression of this marker was noted in moderately & poorly differentiated carcinomas. Conclusion: there is a strong statistical correlation between caspase-3 expression and the degree of tumor differentiation. This may allow the utilization of this marker as a potential prognostic factor, especially in limited biopsy samples

Effective action for the field equations of charged black holes

In this article, we consistently reduce the equations of motion for the bosonic N = 2 supergravity action, using a multi-centered black hole ansatz for the metric. This reduction is done in a general, non-supersymmetric setup, in which we extend concepts of BPS black hole technology. First of all we obtain a more general form of the black hole potential, as part of an effective action for both the scalars and the vectors in the supergravity theory. Furthermore, we show that there are extra constraints specifying the solution, which we calculate explicitly. In the literature, these constraints have already been studied in the one-center case. We also show that the effective action we obtain for non-static metrics, can be linked to the "entropy function" for the spherically symmetric case, as defined by Sen and Cardoso et al.Comment: 18 pages, (v2: small corrections, version to be published in CQG

Non-asymptotically flat, non-AdS dilaton black holes

We show that previously known non-asymptotically flat static black hole solutions of Einstein-Maxwell-dilaton theory may be obtained as near-horizon limits of asymptotically flat black holes. Specializing to the case of the dilaton coupling constant $\alpha^2 = 3$, we generate from the non-asymptotically flat magnetostatic or electrostatic black holes two classes of rotating dyonic black hole solutions. The rotating dyonic black holes of the ``magnetic'' class are dimensional reductions of the five-dimensional Myers-Perry black holes relative to one of the azimuthal angles, while those of the ``electric'' class are twisted dimensional reductions of rotating dyonic Rasheed black strings. We compute the quasi-local mass and angular momentum of our rotating dyonic black holes, and show that they satisfy the first law of black hole thermodynamics, as well as a generalized Smarr formula. We also discuss the construction of non-asymptotically flat multi-extreme black hole configurations.Comment: Minor corrections. 2 references added. To appear in Physical Review

FPGA-based Low Latency Inverse QRD Architecture for Adaptive Beamforming in Phased Array Radars

The main objective of this paper is to facilitate the adaptive beamforming which is one of the most challenging task in phased array radars receivers. Recursive least square (RLS) is considered as the most well suited adaptive algorithm for the applications where beamforming is mandatory, because of its good numerical properties and convergence rate. In this paper, some RLS variants are discussed and the most numerically suitable algorithm Inverse QRD is selected for efficient adaptive beamforming. A novel architecture for IQRD RLS is also presented, which offers low latency and low area occupation for Field Programmable Gate Array (FPGA) implementation. This approach reduces the computations by utilizing the standard pipelining methodology. Hence, efficient adder and multipliers and LUT based solution for square root and division, has highly enhanced the performance of the algorithm. The proposed IQRD RLS architecture has been coded in Verilog and analyze its performance in terms of throughput, hardware resources and efficiency