Maximum power extraction from photo-voltaic power generator with adaptive MPP tracker

Power generation with the help of Photovoltaic (PV) arrays is emphasized increasingly and regarded as an important resource of power energy in the coming years. As the power supplied by PV arrays depends upon the insolation, temperature and array voltage, it is necessary to control the operating point to extract the maximum power from the PV arrays. A number of methods for Maximum Power Point Tracking (MPPT) has been reported in the literature. This paper discusses an adaptive method as well as compares with the conventional fixed step size method, effectively improves the MPPT speed and accuracy simultaneously. An adaptive algorithm and two phase dc-dc Converter is exercised as a MPP tracker. Ripple reduction is possible at input and output side of the converter. Mathematical models of converter are developed using state space averaging technique. The tracking responses of the system operating at the solar array MPP are evaluated. A theoretical analysis of the new algorithm in connection with dc-dc converter is provided and its feasibility is also verified by simulation results.     

Phase transformation of solution‐based p‐type Cu2ZnSnS4 thin film: applicable for solar cell

In this present work, quaternary Cu₂ZnSnS₄ thin films were deposited on commercial glass substrates at room temperature by a novel solution growth dip coating technique. The influence of annealing temperature of the films at 300 °C in a hot air furnace without the presence of any inert gas, on structural, optical, and electrical properties was investigated and discussed. The structural analyses were analyzed by X‐ray diffraction and Raman spectroscopy, whereas optical and electrical properties were analyzed by means of ultra violet infrared (UV‐ViS/IR). The results analyzed showed that there exists a phase formation from orthorhombic to kesterite crystal structure with an increase in optical bandgap and an optical conductivity, with an increase in annealing temperature. The electrical conductivity was observed of the order of 10^?6 ohm cm^?1. Copyright © 2015 John Wiley & Sons, Ltd.     

An automated algorithm for online detection of fragmented QRS and identification of its various morphologies

Fragmented QRS (f-QRS) has been proven to be an efficient biomarker for several diseases, including remote and acute myocardial infarction, cardiac sarcoidosis, non-ischaemic cardiomyopathy, etc. It has also been shown to have higher sensitivity and/or specificity values than the conventional markers (e.g. Q-wave, ST-elevation, etc.) which may even regress or disappear with time. Patients with such diseases have to undergo expensive and sometimes invasive tests for diagnosis. Automated detection of f-QRS followed by identification of its various morphologies in addition to the conventional ECG feature (e.g. P, QRS, T amplitude and duration, etc.) extraction will lead to a more reliable diagnosis, therapy and disease prognosis than the state-of-the-art approaches and thereby will be of significant clinical importance for both hospital-based and emerging remote health monitoring environments as well as for implanted ICD devices. An automated algorithm for detection of f-QRS from the ECG and identification of its various morphologies is proposed in this work which, to the best of our knowledge, is the first work of its kind. Using our recently proposed time–domain morphology and gradient-based ECG feature extraction algorithm, the QRS complex is extracted and discrete wavelet transform (DWT) with one level of decomposition, using the ‘Haar’ wavelet, is applied on it to detect the presence of fragmentation. Detailed DWT coefficients were observed to hypothesize the postulates of detection of all types of morphologies as reported in the literature. To model and verify the algorithm, PhysioNet''s PTB database was used. Forty patients were randomly selected from the database and their ECG were examined by two experienced cardiologists and the results were compared with those obtained from the algorithm. Out of 40 patients, 31 were considered appropriate for comparison by two cardiologists, and it is shown that 334 out of 372 (89.8%) leads from the chosen 31 patients complied favourably with our proposed algorithm. The sensitivity and specificity values obtained for the detection of f-QRS were 0.897 and 0.899, respectively. Automation will speed up the detection of fragmentation, reducing the human error involved and will allow it to be implemented for hospital-based remote monitoring and ICD devices.     

Defect profiling in organic semiconductor multilayers

Defect depth profile study has been carried out in organic semiconductor (OSC) multilayers to characterize the buried interfaces and layers using beam based positron annihilation spectroscopy. The bilayer and trilayer heterostructures (p–n, p–p and n–p–n) comprise of organic–organic and organic–inorganic (substrate) interfaces. Our study reveals the presence of defects at the interfaces whose concentration is seen to vary with the layer thickness. The S–W correlation has been used to examine the effect of organic materials as well as thickness of the layers on the defect microstructure in multilayers. The nature and type of defects in p–p bilayer are seen to be different as compared to p–n and n–p–n multilayers. Positron mobility in OSC layers has been calculated from the fitted diffusion length which is seen to be of the same order as the effective mobility of charge carrier obtained from the measured current density–voltage (J–V) characteristics. The role of structural defects and the intrinsic electric field at the interfaces on positron systematics is also examined. Positron diffusion modeling together with experimental data suggests that the defect at the interfaces has a stronger influence on the positron systematics than the intrinsic electric field across organic–organic interfaces.     

Ultrasoft 100 nm thick zero Poisson's ratio film with 60% reversible compressibility

About a 100 nm thick multilayer film of nanoparticle monolayers and polymer layers is shown to behave like cellular-foam with a modulus below 100 KPa. The 1.25 cm radius film adhered to a rigid surface can be compressed reversibly to 60% strain. The more than 4 orders of magnitude lower modulus compared to its constituents is explained by considering local bending in the (nano)cellular structure, similar to cork and wings of beetles. As the rigidity of the polymer backbone is increased in just four monolayers, the modulus of the composite increases by over 70%. Electro-optical map of the strain distribution over the area of compression and increase in modulus with thickness indicates the films have zero Poisson's ratio.     

Experimental studies on indoor air pollution from domestic cooking appliances

The results of an extensive experimental study undertaken to determine the indoor concentration of several pollutants due to the combustion of domestic cooking fuels in respective appliances are summarised. The primary objective has been the statistical significance testing of the results of the pollution measurements. An attempt was also made to study and analyse the effect of a variety of factors affecting the indoor concentration of pollutants. The results have confirmed that there is statistically significant benefit in replacing the traditional biofuel stoves by improved cookstoves. Replacement of a traditional cookstove using dungcakes with a biogas stove also leads to a statistically significant reduction in the indoor concentration of pollutants. Similarly, a transition from traditional biofuels to kerosene/LPG for domestic cooking is found to lead to a significant reduction in the concentrations of indoor pollutants. However, in a large number of situations the trends observed in the level of pollutant concentration as measured during the experimentation are not statistically significant, and the validity of causal explanations usually given for the variation in the concentration of pollutants (due to change in fuel, fuel feeding rate, monitoring positions, etc.) is rather limited.     

Phenotype and genetic analysis of a syndrome caused by an inactivating mutation in the growth hormone-releasing hormone receptor: Dwarfism of Sindh

We report, in detail, a new form of familial dwarfism, including its phenotypic features, hormonal profile, and molecular basis. Following a newspaper report of severe dwarfism in two villages in the province of Sindh, Pakistan, we organized an expedition to study its clinical, genetic, and molecular characteristics. We identified 18 dwarfs (15 male, 3 female), all members of a consanguineous kindred, ranging in age from newborn to 28 yr. Mean height was 7.2 SD below the norm, with mean adult heights of 130 cm for males and 113.5 cm for females. Body proportions and habitus were normal; but head circumference was 4.1 SD, and blood pressure approximately 3 SD below the norm. There was no dysmorphism, no microphallus, and no history of hypoglycemia. Serum GH did not respond to provocative stimuli (GHRH, L-dopa, or clonidine). Insulin-like growth factor I (IGF-I) and IGF-binding protein 3 were low (5.2 +/- 2.0 ng/mL and 0.42 +/- 0.13 microg/mL, respectively; mean +/- SD) but rose normally with GH treatment. One affected, dwarfed couple had a son, demonstrating fertility in both sexes. Clinical and endocrinological evidence suggested isolated GH deficiency with a recessive inheritance pattern. The GH-N gene was found to be intact. Linkage analysis of microsatellite chromosomal markers near other candidate genes yielded a high LOD score (6.26) for the GHRH receptor (GHRH-R) locus. DNA sequencing revealed a nonsense mutation (Glu50-->Stop) in the extracellular domain of the GHRH-R. This mutation predicts a severely truncated GHRH-R; it is identical to that recently reported in four patients from two other families. Inheritance is autosomal recessive (chromosome 7p) with a high degree of penetrance. Relatives heterozygous for the mutation had moderately decreased IGF-I levels and slightly blunted GH responses to GHRH and L-dopa, but they showed only minimal or no height deficit. This syndrome represents the human homologue of the little (lit/lit) mouse and closely resembles its phenotype. It demonstrates the absolute requirement of GHRH signaling for pituitary GH secretion and postnatal growth in humans, and its relatively minor (but discernible) biological importance in extrapituitary sites. The syndrome is distinct from other forms of GH deficiency with respect to microcephaly, asymptomatic hypotension, and absence of features such as facial dysplasia, significant truncal obesity, microphallus, or hypoglycemia. Its discovery raises the possibility of milder mutations in the GHRH-R gene as potential causes for partial GH insufficiency and idiopathic short stature.     

High-Resistance Faults on Two Terminal Parallel Transmission Line: Analysis, Simulation Studies, and an Adaptive Distance Relaying Scheme

Performance of conventional nonpilot distance relay is affected by ground fault resistance, prefault system conditions, mutual effects of parallel lines and shunt capacitance influences. The work presented in this paper addresses the problems encountered by conventional non pilot distance relay when protecting two terminal parallel transmission lines. One of the key points of this paper is the detailed analysis of the apparent impedance as seen from the relaying point taking into account the effects of transmission line parameter uncertainties, mutual effects of parallel lines for simple and more complex configuration, shunt capacitance influences and variations in the system external to the protected line. Based on extensive computer simulations of the infeed/outfeed, fault resistance, mutual coupling and shunt capacitance effects on the relay characteristics, an adaptive digital distance relaying scheme is proposed using radial basis function neural network which provides more efficient approach for training, computation, adaptation and tripping than the conventional feed forward network using back propagation algorithm. In addition, the proposed adaptive scheme improves the performance of distance relay for double-circuit lines using modified compensation factor. Moreover, the scheme does not require separate communication channel for data transmission. The results of computer simulation show the improvement of sensitivity and selectivity of the relay     

New differential protection scheme for tapped transmission line

The development of a new differential protection scheme for tapped transmission lines using wavelet transform is presented. At each relay locations, using the most suitable mother wavelet, the measured three line currents are decomposed up to third level. Thereafter, third-level approximation coefficients are reconstructed and used to derive the operating and restraining quantities. The proposed scheme has been tested extensively using the PSCAD/EMTDC software package with fault data, generated by modelling UKAI-KAKRAPAR 400 kV line of the Indian power system. The proposed scheme eliminates many of the problems encountered with tapped transmission lines such as high resistance faults, out feed current in case of internal and external faults, insufficient current for tripping and provides better discrimination between external and internal faults in case of loss of generation at one end. At the end, a comparative evaluation of the conventional current differential protection scheme with the proposed scheme is also presented. Dependability and security have been studied separately.