In this brief, a new non-isolated high gain DC-DC converter topology is proposed to attain the high-voltage conversion ratio. The high-voltage conversion ratio is achieved without utilizing the ...coupled inductors and any transformers. The proposed topology utilizes a single power semiconductor switch and its operation is examined under continuous conduction mode (CCM), discontinuous conduction mode (DCM) and boundary conduction mode (BCM). The theoretical analysis and design procedure for passive components are provided with mathematical expressions. The validity of the theoretical analysis is examined by using a laboratory prototype of the proposed converter with a power rating of 200 W. The experimental results are taken under CCM with a 60% duty cycle. The proposed topology is also examined with dynamic changes in duty cycle value and load values. The efficiency and power density of the proposed converter are 90% and 1.03kW/L.
Abstract
In this article, attempts are made to grow large size PZN-PT single crystals using high temperature solution growth method by implementing novel bottom cooling technique. The grown crystals ...are oriented and poled along 〈001〉 direction and obtained larger piezoelectric strain coefficient (d
33
> 2000 pm V
−1
) suitable for development of underwater acoustic sensor requirements. Flexural mode hydrophone is realized using the oriented PZN-PT single crystal discs. Finite element modeling is employed to examine the design of the flexural mode hydrophone and an equivalent circuit model is also applied to study its acoustic characteristic at two extreme boundary conditions like simply supported and clamped edge condition. The underwater acoustic response of the PZN-PT single crystal based flexural mode hydrophone is evaluated over the frequency range (100 Hz to 12 kHz) and its responses are compared with the FEM and equivalent circuit model results. The predicted results from FEM and equivalent circuit model are found to be in good agreement with the experimental results. The receiving sensitivity of the PZN-PT single crystal-based hydrophone is 12 dB higher than the PZT 5A based hydrophone in the frequency range of 2 kHz to 6 kHz. The fabricated PZN-PT single crystal-based hydrophone offers better performance than the conventional piezo ceramic based flexural hydrophone.
The greenhouse environment is a complex multi-scale integrated nonlinear system. This agro-ecosystem is composed of crop and greenhouse climate which are based on the existence of two different ...timescales. The effect of temperature plays a vital role in the variation of phenotypic data in crop growth. Thus, two different models, one for capturing the climate dynamics inside the greenhouse and other for crop dynamics, are essential. First, the neural network is used to predict the inside environment, given the outside conditions and the operation of the control equipment. The inputs of the network are meteorological parameters, whose measurements are costly and time consuming to acquire. So, instead of measuring all the parameters used in the physical modeling, the most significant relevant input parameters which give same modeling efficiency are identified. To avoid overfitting of the data and to realize the best prediction results with the simplest structure, an enhanced pruning algorithm is implemented for topology optimization of the artificial neural network. The pruning algorithm is discussed and exemplified via simulations. By plotting the training error, test error, and final prediction error (FPE) estimates over the course of pruning the network weights, it is inferred that a network with minimum of 15 weights is reliable to model greenhouse environment dynamics. With the Optimal Brain Surgeon (OBS) algorithm, a reduction of the number of weights from 141 to 76 (46%) in the first step and finally to 15 (89%) was achieved and the percentage prediction error is reduced from 13.13% for the complete network structure to 4.35% for final pruned network. Secondly, in order to study the progress of crop ontogeny, bootstrap resampling-based artificial neural network is developed with limited destructive measurements. The notion of prediction performance and the efficiency of the bootstrapped crop phenotypic neural network model are evaluated by root mean square error (RMSE), mean square error (MSE) and Nash and Sutcliffe efficiency (NSE) criteria. The net assimilation rate which determines the growth rate of the plant inside the greenhouse environment is calculated. The resulting model can be used for growth assessment, understanding crop physiology and yield prediction.
This work deals with phytochemical synthesis of TiO
2
nanoparticles by using leaf extract of
Ficus benghalensis
tree and evaluation of their antibacterial and photocatalytic activities. The ...synthesized TiO
2
nanoparticles were characterized by using X-ray diffraction, Attenuated total reflectance Infrared, UV visible spectroscopy and transmission electron microscopy as well as scanning electron microscopy techniques. The characterizations revealed formation of stable, spherical nanoparticles of anatase phase of TiO
2
with average diameter of 21 nm. The particles showed excellent antibacterial activity against
Bacillus cereus
(Gram-positive) and
Escherichia coli
(Gram-negative) bacteria. The photocatalytic testing showed complete degradation of model pollutants from cationic and anionic dye family namely methylene blue (cationic dye) and methyl orange (anionic dye) that confirmed the excellent photocatalytic activity of the particles.
Eu3+-doped ZnAl2O4 phosphors were successfully synthesized in air atmosphere at 900°C. The phosphors were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermally ...stimulated luminescence (TSL) and photoluminescence (PL) techniques. The average particle size of the system as determined from SEM was found to be 100–150nm (for samples annealed at 900°C). PL spectra of the doped phosphors showed emission peaks corresponding to Eu3+ ions. Lifetime studies revealed Eu3+ ions to be in two different sites. The asymmetric ratio (I616/I592) was observed to be about 3.75. This suggested that Eu3+ ion entered the host mainly substituting Al3+ site distorting the local environment and is partly located on surface of the phosphors. A prominent glow peak at 430K was observed in the TSL of γ-irradiated Eu3+-doped ZnAl2O4 phosphors. Trap parameters for this peak have been determined and the probable mechanism for the glow peak is proposed. CIE chromaticity coordinates for the system were evaluated. It was observed that, the system could be employed as a potential red emitting phosphor. Commercial utility of the phosphor was investigated by comparing it with commercial red phosphor. The PL intensity of the as prepared phosphors was 63% of that of the commercial phosphor. Apart from this, various radiative properties such as the Judd–Ofelt intensity parameters, spontaneous emission probabilities, luminescence branching ratios, radiative lifetimes and quantum efficiency were evaluated for the system.
► Paper deals with synthesis and characterization of Eu3+-doped ZnAl2O4 phosphor. ► Apart from PL and TSL characterizations, CIE coordinates were determined. ► The Judd–Ofelt intensity parameters and quantum efficiency were evaluated. ► The system could be employed as a potential red emitting phosphor.
Background: Mental illnesses are becoming a major health issue across the world. The availability of inpatient facilities for mentally ill patients is very much limited in developing countries such ...as India. Aim: This study was aimed to explore the pattern of psychiatric admissions at a general hospital psychiatry unit (GHPU) in South India. Methodology: The study was conducted at a multispecialty tertiary care hospital in South India. A retrospective, chart-based study design was adopted to achieve the objectives. All inpatient case records available from the department of psychiatry, the medical records department, and the electronic hospital information system of the institute were reviewed between April 2006 and March 2016. Results: A total of 3082 patients were admitted as psychiatry inpatients during the 10-year study period, representing an average of 308.2 admissions per calendar year. The majority of inpatients were male (n = 1824; 59.2%). Concerning diagnostic categories, mood disorders were accounted for 33.6% of admissions, followed by psychotic disorders (26.4%) and substance use disorders (19.3%), respectively. The median length of hospital stay was 14 days (range 0-163 days). A statistically significant seasonality pattern was noticed for mood disorders (December to February) and anxiety and neurotic disorders (August to October). Conclusion: It is obvious that treatment-seeking attitude among individuals with mental illnesses is increasing and the awareness regarding treatment aspects is also increasing among the general public. Hence, there is a need to improve the existing resources to facilitate intensive management for better treatment outcomes and this, in turn, will enhance the quality of life of mentally ill individuals.
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•Optimization of U concentration for maximum PL yield and mechanism of quenching.•Identification of the two types of uranium species (UO66-) present in the SBO matrix.•Evaluation of ...the TSL trap parameters and the order of the kinetics.•Formation of BOHC, BOEC and oxygen defect centers on gamma irradiation.•Proposition of a plausible mechanism for the observed photo and thermo luminescence.
The luminescence of uranium in strontium borate (SrB4O7, SBO) matrix was investigated by time resolved photoluminescence, thermoluminescence (TSL) and electron spin resonance techniques (ESR). The samples were synthesized using solid state fusion reaction route and characterized by X-ray diffraction. Photoluminescence excitation and emission data suggested the stabilization of uranium as uranate (UO66-) in the matrix. Luminescence decay time data suggested the stabilization of uranium at two different sites in the matrix. By giving suitable delay times and choosing proper gate widths, the two emission spectra due to the two uranate species could be obtained. Thermoluminescence investigation on the gamma-rays irradiated sample showed a strong glow peak at ∼415K and a weak glow peak at 505K. The dose response behavior, the trap parameters along with the order of kinetics for the strong glow peak were determined. To pinpoint the exact chemical nature of the defect centers responsible for the observed glow peaks, electron spin resonance technique was employed. Based on the ESR-TSL correlation data and the observed photoluminescence results, a plausible mechanism for the origin of the luminescence in the system was proposed.
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