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In this article, a radiofrequency (RF) coil that can produce a high electromagnetic field homogeneity to be used for Magnetic Resonance Imaging (MRI) applications is pondered. Helmholtz Coils are a special arrangement of loops such that when an electric current is applied to them, the resultant magnetic field generated between the coils is extremely uniform. Coils configured in this way are also used for applying or measuring fields and are useful for experiments and calibration where a known ambient magnetic field is required. Helmholtz coils play an important role to acquire magnetic resonance images with maintaining good magnetic field homogeneity. In this work, a square Helmholtz coil is designed and tested. The main objectives are to calculate the magnetic field provided by the square Helmholtz coils at any point in space and to show that it is uniform. Simulation is one of the most important parts of this work by which mathematical equations are simulated to investigate the axial magnetic field produced by square loops. Also, electrical modeling for Square Helmholtz coils is carried out. Besides this, the square Helmholtz coil is implemented experimentally and the theoretical and practical results are compared.

With the fast emerge of renewable sources, remote locations started to utilize Microgrids to provide the required power. The Microgrid could be connected to a utility grid, and in many situations it may serve as a small isolated grid. An islanded Microgrid is subjected to many disturbances throughout the day e.g. load profile and power generation changes. The case gets even worse when this small grid is exclusively driven by renewable sources such as wind and power; which are dependent on wind speed and sun radiation. It is very challenging to control the voltage and frequency of a Microgrid to meet the desired output when a Microgrid is not connected to utility grid. This paper provides a literature survey of the latest proposed frequency control techniques of islanded Microgrids, which could be equipped with energy storage equipment or could be connected to utility grid when needed. Also, the paper will contribute in testing H ∞ and μ-Synthesis frequency control approaches for paper [4] modified model to be two-bus Islanded Microgrid model.

Power system availability is very important in terms providing continues power supply with no interruption. However, faults are existing in power systems due to equipment aging, unexpected behavior from a specific equipment or sometimes from human errors during operation and maintenance. In order to limit the fault to the equipment and preventing this fault from damaging other equipment or effecting the system behavior, relays are developed. Relays are instrument equipment continuously monitoring the system and taking a proper action according to the situation. The decision and the time delay for the action based on the fault type. The input data to the relay are the faults' type and how bad they are. Digital Signal Processing (DSP) will take samples from the inputted data continuously and take an action when needed. The internal connection and how DSP is utilized in protective relays will be discussed in this paper. In addition, a SIMULINK case study is included to see the DSP effect on protective relaying.

Rapid advances in technology, that made almost everything goes digital have entailed a persistent need for a stronger means of information security. Furthermore, new advanced devices are now available to capture the dynamic of a person's signature. Therefore, the reliance on the dynamic signature for authenticating entities in secure system became crucial. In this paper, we investigate the problem of dynamic signature verification and recognition using Ensemble of Classifiers, where we used multiple Fisher based probabilistic neural networks as the component classifiers to construct the Ensemble. Two key issues are studied; the first issue is how to construct the Ensemble. The second issue is how to combine the predictions of the component classifiers in order to accomplish the decision-making process. Data sets from SVC dataset have been used to assess the performance of the proposed ensemble of classifiers. Obtained results are very encouraging and show the ability of ensemble classifiers to deal with the tackled problem.

GaSb-based quantum well lasers have been optimized for high coupling efficiency into an optical system. The use of a V-shaped Weaker Waveguide in the n-cladding layer is shown to dramatically reduce vertical beam divergence without any performance degradation compared to a conventional broad-waveguide laser structure. Starting from a broad waveguide laser structure design which gives low threshold current and a large vertical far-field (VFF), the structure was modified to decrease the VFF while maintaining a low threshold-current density. In a first step the combination of a narrow optical waveguide and reduced refractive index step between the waveguide and the cladding layers reduces the VFF from 67o to 42o. The threshold current density was kept low to a value of ~190 A/cm2 for 1000×100 μm2 devices by careful adjustment of the doping profile in the p-type cladding layer. The insertion of a V-Shaped Weaker Waveguide in the n-cladding layer is shown to allow for further reduction of the VFF to a value as low as 35o for better light-coupling efficiency into an optical system without any degradation of the device performance.

Compressively-strained InGaAsP QW active (/spl lambda/=732 nm) diode lasers achieve 2.4 W CW front-facet power from 100 /spl mu/m-wide apertures, with reliable operation at 0.5 W CW. Record-high characteristic temperatures for the threshold current and the differential quantum efficiency, T/sub 0/=115 K and T/sub 1/=285 K are obtained by growing on misoriented substrates.

Compressively-strained InGaAsP QW active (/spl lambda/=732 nm) diode lasers achieve 2.9 W CW front-facet power from 100 /spl mu/m-wide apertures, with reliable operation demonstrated at 0.5 W CW. Record-high characteristic temperature coefficients; T/sub 0/=115 K and T/sub 1/=285 K, are obtained by growing on misoriented substrates.

100 /spl mu/m-wide stripe, 0.97 /spl mu/m-emitting Al-free InGaAsP-InGaP-GaAs QW lasers, demonstrate a record value for quasi-CW output power, 14.3 W, low internal losses (/spl alpha/=1 cm/sup -1/), and high differential quantum efficiency (86% for 2 mm-long lasers). Long cavity, large-stripe devices exhibit relatively small spectral broadening with increased output power.

The use of an InGaAsP quantum well (QW) active region offers the intriguing possibility of realizing reliable high-power operation at short wavelengths (730 nm). We employ high bandgap cladding layers and confining layers to suppress carrier leakage along with a 1.5% compressively strained InGaAsP QW. The structure was grown on [100] substrates misoriented 10" toward (111) A by low-pressure metal-organic chemical-vapor deposition (LPMOCVD).

Here we present a 1.3-/spl mu/m waveguide laser structure, designed to suppress second-order-mode oscillation, that operates to record-high cw power for any type of InGaAs active diode lasers. It also emits in a pure fundamental transverse mode to at least 20 W peak pulsed power.

Summary form only given. 0.78 /spl mu/m, Al-free active-region, compressively-strained (/spl Delta/a/a=0.85%) InGaAsP quantum well diode lasers have been grown by MOCVD. Broad-stripe (100 /spl mu/m-wide) devices exhibit low threshold current densities, 290 A/cm/sup 2/ (L=1 mm), and cw front-facet output powers of 2.2 W.