Modeling and simulation of three phases cascaded H-bridge grid-tied PV inverter

In this paper a control scheme for three phase seven level cascaded H-bridge inverter for grid tied PV system is presented. As power generation from PV depends on varing environmental conditions, for extractraction of maximum power from PV array, fuzzy MPPT controller is incorporated with each PV array. It gives fast and accurate response. To maintain the grid current sinusoidal under varying conditions, a digital PI controller scheme is adopted. A MATLAB/Simulink model is developed for this purpose and results are presented. At last THD analysis is carried out in order to validate the performance of the overall system. As discussed, with this control strategy the balanced grid current is obtained keeping THD values with in the specified range of IEEE-519 standard

Processing and Characterization of Fly Ash - Quartz Coatings

Fly ash emerges as the major waste material of many thermal power plants. It mainly comprises of oxides of silicon, aluminium, iron, and titanium along with some other minor constituents. The present investigation explores the coating potential of this industrial waste. It envisages the processing and characterization of a series of plasma sprayed coatings made with fly ash premixed with quartz, which is a low cost mineral available in plenty. These materials do not belong to the so-called “plasma sprayable” category. These have been deposited on mild steel and copper substrates by atmospheric plasma spraying. Utilization of such kind of industrial waste as coating material minimizes the cost of plasma spray deposition process, which posed to be the major hindrance to its wide spread application due to high cost of the spray grade powders. Using atmospheric plasma spraying system coatings are deposited on metal substrates at different operating power levels of the plasma torch ranging from 11kW to 21kW and then characterization of the coatings is carried out. The properties of the coating depend on the materials used, operating condition and the process parameters. The plasma spraying process is controlled by the parameter interdependencies, co-relations and individual effect on coating characteristics. The particle sizes of the raw materials used for coating are characterized using Laser particle size analyzer. Deposition efficiency is an important factor that determines the techno economics of the process. It is evaluated for the deposited coatings. Coating interface bond strength is evaluated using coating pull out method, confirming to ASTM C-633 standard. In view of tribological applications, hardness is one of the most required mechanical properties. Hardness measurement is done on the polished cross section of the samples using Leitz Micro-Hardness Tester. Coating porosity is measured by image analysis technique. To ascertain the phases present and phase changes / transformation taking place during plasma spraying, XRD analysis is made. Coating surface & interface morphology is studied with Scanning Electron Microscope. To study the suitability of the coatings for wear resistance application, wear properties of these coatings are studied. The erosion wear behaviour of these coatings is evaluated with solid particle erosion tests under various operating conditions. In order to control the wear loss in such a process, one of the challenges is to recognize parameter interdependencies; correlations and their individual effects on wear so that the coating can be useful for tribological application. Statistical analysis of the experimental results using Taguchi experimental design is presented. Spraying parameters such as impact angle, size of the erodent, standoff distance and impact velocity are identified as the significant factors affecting the coating erosion wear. Other statistical techniques like ANN and SYSTAT have also been very much useful in predicting the experimental data with a larger domain. This work establishes that fly ash-quartz mixture can be used as a potential coating material suitable for depositing plasma spray coating. It also opens up a new pathway for value added utilization of this industrial waste and low-grade ore mineral

Fabrication and Characterization of PVDF - PZT (Navy type-VI) composites

Our work comprises preparation of homogeneous ceramics-polymer composites consisting of PZT (Navy Type VI) particles in the form of fillers and PVDF polymer as matrix, using a solution casting process. The structural, microstructural and dielectric properties of the composites film were investigated by X-ray Diffraction, Field Emmision Scanning Electron Microscopy, LCR Meter, respectively and discussed. The X-ray diffraction patterns indicate that with the addition of PZT, the polymer peak gradually flattens. PVDF matrix of the PVDF-PZT composite is contains mixture of á and â phase. The FESEM images show a uniform distribution of ceramic fillers in the polymer matrix. The composites prepared show greater dielectric permittivity and a reduced loss tangent. The results suggest that the introduced ceramic PZT fillers have a good influence on the polymer matrix and contribute to the improvement of the dielectric behaviour of the composites.

Characterizations of Sol gel Synthesized (1-x)BZT-xBCT Ceramics

Barium zirconate titanate – Barium calcium titanate [(1-x)BZT-xBCT] (48BZT-52BCT, 50BZT-50BCT, 52BZT-48BCT) ceramic were prepared by sol-gel method. The sample was calcined at 1100°C. The X-Ray diffraction of calcined powder showed the formation of single pervoskite phase with no impurity peaks. 48BZT-52BCT, 50BZT-50BCT and 52BZT-48BCT were sintered at two temperatures i.e., 1200°C and 1300°C. The SEM images of the sintered pellets showed that the grain size varied from 800nm to 2μm. The dielectric property was studied under the frequency range from 100 Hz to 1 MHz and also by varying the temperature from 30°C to 200°C. The PE Loop of the sample was obtained by PE Loop tracer which confirmed the ferroelectric effect in 48BZT-52BCT, 50BZT–50BCT, 52BZT-48BCT ceramics

Fuzzy Inference System Approach for Locating Series, Shunt, and Simultaneous Series-Shunt Faults in Double Circuit Transmission Lines

Many schemes are reported for shunt fault location estimation, but fault location estimation of series or open conductor faults has not been dealt with so far. The existing numerical relays only detect the open conductor (series) fault and give the indication of the faulty phase(s), but they are unable to locate the series fault. The repair crew needs to patrol the complete line to find the location of series fault. In this paper fuzzy based fault detection/classification and location schemes in time domain are proposed for both series faults, shunt faults, and simultaneous series and shunt faults. The fault simulation studies and fault location algorithm have been developed using Matlab/Simulink. Synchronized phasors of voltage and current signals of both the ends of the line have been used as input to the proposed fuzzy based fault location scheme. Percentage of error in location of series fault is within 1% and shunt fault is 5% for all the tested fault cases. Validation of percentage of error in location estimation is done using Chi square test with both 1% and 5% level of significance

Early white-matter abnormalities of the ventral frontostriatal pathway in fragile X syndrome

AIM—Fragile X syndrome is associated with cognitive deficits in inhibitory control and with abnormal neuronal morphology and development. METHOD—In this study, we used a diffusion tensor imaging (DTI) tractography approach to reconstruct white-matter fibers in the ventral frontostriatal pathway in young males with fragile X syndrome (n=17; mean age 2y 9mo, SD 7mo, range 1y 7mo–3y 10mo), and two age-matched comparison groups: (1) typically developing (n=13; mean age 2y 3mo, SD 7mo, range 1y 7mo–3y 6mo) and (2) developmentally delayed (n=8; mean age 3y, SD 4mo, range 2y 9mo–3y 8mo). RESULTS—We observed that young males with fragile X syndrome exhibited increased density of DTI reconstructed fibers than those in the typically developing (p=0.001) and developmentally delayed (p=0.001) groups. Aberrant white-matter structure was localized in the left ventral frontostriatal pathway. Greater relative fiber density was found to be associated with lower IQ (Mullen composite scores) in the typically developing group (p=0.008). INTERPRETATION—These data suggest that diminished or absent fragile X mental retardation 1 protein expression can selectively alter white-matter anatomy during early brain development and, in particular, neural pathways. The results also point to an early neurobiological marker for an important component of cognitive dysfunction associated with fragile X syndrome

FiND: Few-shot three-dimensional image-free confocal focusing on point-like emitters

Confocal fluorescence microscopy is widely applied for the study of point-like emitters such as biomolecules, material defects, and quantum light sources. Confocal techniques offer increased optical resolution, dramatic fluorescence background rejection and sub-nanometer localization, useful in super-resolution imaging of fluorescent biomarkers, single-molecule tracking, or the characterization of quantum emitters. However, rapid, noise-robust automated 3D focusing on point-like emitters has been missing for confocal microscopes. Here, we introduce FiND (Focusing in Noisy Domain), an imaging-free, non-trained 3D focusing framework that requires no hardware add-ons or modifications. FiND achieves focusing for signal-to-noise ratios down to 1, with a few-shot operation for signal-to-noise ratios above 5. FiND enables unsupervised, large-scale focusing on a heterogeneous set of quantum emitters. Additionally, we demonstrate the potential of FiND for real-time 3D tracking by following the drift trajectory of a single NV center indefinitely with a positional precision of < 10 nm. Our results show that FiND is a useful focusing framework for the scalable analysis of point-like emitters in biology, material science, and quantum optics.Comment: 17 pages, 7 figure

Morphometric Spatial Patterns Differentiating Boys With Fragile X Syndrome, Typically Developing Boys, and Developmentally Delayed Boys Aged 1 to 3 Years

Brain maturation starts well before birth and occurs as a unified process with developmental interaction among different brain regions. Gene and environment play large roles in such process. Studies of genetic disorders such as fragile X syndrome (FXS) which is a disorder caused by a single gene mutation resulting in abnormal dendritic and synaptic pruning, together with healthy individuals may provide valuable information

A novel primary and backup relaying scheme considering internal and external faults in HVDC transmission lines

Discrimination of different DC faults near a converter end of a DC section consisting of a filter, a smoothing reactor, and a transmission line is not an easy task. The faults occurring in the AC section can be easily distinguished, but the internal and near-side external faults in the DC section are very similar, and the relay may cause false tripping. This work proposes a method to distinguish external and internal faults occurring in the DC section. The inputs are the voltage signals at the start of the transmission line and the end of the converter filter. The difference in voltage signals is calculated and given to an intelligent controller to detect and discriminate the faults. The intelligent controller is designed using machine learning (ML) and deep learning (DL) techniques for fault detection. The long short-term memory (LSTM-) based relay gives better results than other ML methods. The proposed method can distinguish internal from external faults with 100% accuracy. Another advantage is that a primary relay is suggested that detects faults quickly within a fraction of milliseconds. Nevertheless, another advantage is that a backup relay has been designed in case the primary relay cannot operate. Results show that the LSTM-based protection scheme provides higher sensitivity and reliability under different operation modes than the conventional traveling wave-based relay

Neuroanatomy of fragile X syndrome is associated with aberrant behavior and the fragile X mental retardation protein (FMRP)

To determine how neuroanatomic variation in children and adolescents with fragile X syndrome is linked to reduced levels of the fragile X mental retardation-1 protein and to aberrant cognition and behavior