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In this paper, the design and implementation of a dsPIC microcontroller-based photovoltaic (PV) microinverter control scheme using Direct Digital Synthesis (DDS) technique has been presented. The proposed scheme has the inherent voltage phase detection with phase-locked loop in a DQ reference frame and all control features implemented via the DDS technique adopted. The advantages of DDS technique...
In this paper, the design of a microcontroller-based control scheme for grid-tie photovoltaic (PV) microinverters using Direct Digital Synthesis (DDS) technique has been presented. The proposed control scheme based on DDS technique has capabilities such as, phase locked-loop generation, maximum power point tracking, anti-islanding and fault ride-through capability, which are essential requirements...
Progress in bio-printing techniques has accentuated the need for non-invasive imaging modalities with high sensitivity, high resolution, and imaging depth of a few millimeters. Mesoscopic Fluorescence Molecular Tomography (MFMT) is a promising imaging modality for 3D localization and quantification of fluorescent labeled cells in thick scaffolds. Here we report on the characterization of our second...
Recent advances in tissue engineering applications demand micro-scale precision in both design and evaluation. Herein, we aim to meet these challenges through a combination of two innovative techniques: gelatin-based Laser Direct-Write (LDW) and Mesoscopic Fluorescence Molecular Tomography (MFMT). LDW was used to precisely pattern cell-loaded, alginate microbeads, in layer-by-layer fashion, to construct...
Current Laminar Optical Tomography (LOT) systems differ in their optical design, mainly in scanning mode strategies and detector selection. Herein, we investigate the design for an LOT system with an Electron Multiplying CCD camera in de-scanning mode. In de-scanning mode, the image of the detectors is scanned on the surface of the sample in conjunction with the raster scanned illumination spot. De-scanning...
In this paper, the design and implementation of a dsPIC microcontroller-based photovoltaic (PV) microinverter has been presented. The flyback PV microinverter is controlled via a low-cost dsPIC microcontroller circuit, with the duty cycle variation of the power switch generated directly from the AC grid voltage, or from a reference sinusoidal waveform at power frequency in the case of standalone applications...
Fluorescence imaging is the main method in assessing tissue engineered constructs. However, with the drive to develop thick engineered constructs, it is imperative to develop new fluorescence based techniques that can image beyond the depth capabilities of current microscopic techniques. Here we report the use of Laminar Optical Tomography (LOT) to image in 3D vascular channels, formed by GFP and...
The authors study the operation of carbon nanotube thin-film transistors (CNT-TFT) at elevated temperatures. Due to the small bandgap of semiconducting carbon nanotubes, CNT-TFTs are not suitable to be developed as high-temperature devices. However, CNT-TFTs will still have to endure elevated temperatures when employed in large-area and flexible electronic applications. The temperature range that...
In this paper, a novel robust watermarking technique based on discrete cosine transform using genetic algorithm (GA) is presented. To obtain highest possible robustness without losing transparency, GA is used for adjustment of mid-band coefficients. Significant improvements in robustness under attacks and also in transparency are obtained from experimental results.
In this paper, the position sensorless direct torque and indirect flux control (DTIFC) of BLDC motor with non-sinusoidal (non-ideal trapezoidal) back-EMF has been extensively investigated using three-phase conduction scheme with six-switch inverter. In the literature, several methods have been proposed to eliminate the low-frequency torque pulsations for BLDC motor drives such as Fourier series analysis...
Several watermarking schemes have been proposed with the purpose of copyright protection and access control for multimedia objects. In this paper, an optimal discrete wavelet transform-singular value decomposition (DWT-SVD) based image watermarking scheme using particle swarm optimizer (PSO) is presented. Proposed DWT-SVD based watermarking algorithm initially decomposes the host image into subbands,...
In this paper, a novel fragile watermarking scheme based on discrete cosine transform (DCT) using particle swarm optimization (PSO) algorithm is presented. Embedding watermarks in frequency domain can usually be achieved by modifying the least significant bits (LSBs) of the transformation coefficients. After embedding process is completed, a number of rounding errors appear due to conversion of real...
This paper discusses the space strategy that provides a clear vision for space activities. This strategy includes many activities in an effective harmonisation to achieve the vision requires a cohesive technology strategy that brings together the institutional, commercial and scientific objectives and responds to the challenges for technology strategy and innovation.
In power systems transients caused by energization of power transformers and voltage dip are some of the more common problems. Voltage recovery after a voltage dip can produce transformer saturation. This saturation produces an inrush current similar to that of the transformer energizing. In this paper transformer inrush current resulting by voltage dip is analyzed by using full period sliding window...
In power systems, the transients caused by the energization of the power transformers and the voltage sags are some of the more common problems. The voltage recovery after voltage sag can saturate the transformer and this saturation can produce an inrush current, which is similar to that of the energizing. In this paper transformer inrush currents resulting from voltage sags with and without phase...
The effects of non-sinusoidal voltages on the performance of an over/under voltage relay were experimentally studied. The frequency and amplitude of individual harmonics were adjusted with a programmable power source and the operating times of the relay are examined. The relation between the harmonic voltages and relay behavior is determined. The measurements show that the relay may operate slower...
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