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Luminescent ZnIn2S4 NCs with PLQYs up to 11% have been isolated by a simple route involving metal xanthates co-thermolysis. Also, size dependent PL emission, optical band gap properties and carrier life time measurements of these NCs are presented.

This article presents the synthesis of a single-phase red emitting Y2Ge2O7:Eu3+ soft-UV excitable phosphor with up to 10% Eu3+ content. Experimental and theoretical exploration has established its relative potential with respect to the commercial Y2O3:Eu3+ phosphor.

Performance analysis of the interleaved high-gain converter with active switched inductor using an intelligent controller is presented in this article. In this proposed work, an intelligent controller is designed for an interleaved high-gain converter to enhance the performance in terms of high voltage gain, less input current ripple, output voltage ripple and high efficiency. A large amount of input ripple current is generated due to parallel charging of the inductor (ON and OFF time interval). This high ripple current will cause heating in circuit elements and also reduce the efficiency of the system. Furthermore, it also reduces the current carrying capacity of the inductor by 50%. The continuous power to the load is delivered, by turn on of a pair of semiconductor switches alternatively, i.e. 1800 phase shift between the converters. The dynamic performance of the converter is evaluated in terms of line and load disturbances with the help of an intelligent controller and the performance comparison of the converter is also carried out with respect to the duty cycle. This intelligent controller-based converter is simulated using MATLAB/Simulink software, and results are verified through field programmable gate array (FPGA)-based experimental setup.

The dominant intensity of parity-forbidden intra-4f transitions of europium(III) over O → Eu charge-transfer band (CTB) intensity is against common perceptions, yet this trend is observed in many g...

Glass and glass-ceramics play vital roles in today’s technology development. Although glasses are known to mankind from pre-historic period, its wide applicability as a candidate for various technological applications was realized during the past century. Advancement in communication technology was mainly possible with fabrication of high quality glass fibers. Glass-ceramics are derived from glasses and possess both the advantages of glasses and ceramics. In this chapter, initially, the origin of glasses and glass-ceramics are discussed followed by their classification depending up on the nature of glass forming constituents. Synthesis routes for preparation of different types of glasses are discussed in detail. Thermodynamics and kinetics of glass formation and its conversion to glass-ceramics are explained towards end of the chapter. Structure property correlation is an important aspect in any studies involving material development and this aspect is explained in detail in this chapter. Techniques like solid-state NMR, XPS, EXAFS which give mainly information on short-range order in glasses have been explained with examples. Importance of thermal techniques for understanding glass and ceramic science has been brought out in this chapter. Finally, the chapter ends with certain representative applications of glasses and glass-ceramics.

Electroluminescent devices are going through new developments these days. We have proposed a wearable blue light emitting electroluminescence device (EL) for reducing the person’s blood pressure. The EL device was fabricated using screen printing procedure. The developed alternating current electroluminescent device (ACEL) consists of the bottom electrode as indium tin oxide (ITO), barium titanate paste as dielectric layer and silver paste as the upper electrode and ZnS: Cu as the phosphor layer, respectively. The fabricated EL device emits blue light. We have also simulated a PCB in proteus which converts DC voltage to AC voltage. The output AC voltage can be used as the power supply for the EL device. Studies demonstrated that exposure to blue light can reduce the systolic blood pressure of a human being by releasing nitric oxide from skin cells into the circulating blood which reduces the arterial stiffness and contributes to better cardiovascular health. The integration of the power supply PCB with the fabricated electroluminescence display which enables blue light exposure to the person wearing EL device, can decrease the person’s systolic blood pressure. It has been observed from the color purity of the fabricated EL device that the emitted light has coordinates of (0.20,0.23) which represents the region of blue light in CIE Plot.

The dominant intensity of parity-forbidden intra

DC to DC conversion at high voltage gain is an imperative feature for many applications particularly for photovoltaic grid-connected system. The voltage conversions at large gain in boost converter are restricted due to the diode reverse-recovery problem and the stress on the switch. In this paper, a hybrid boost converter (HBC) that operates at high voltage gain is analyzed. This converter topology has better features like large voltage conversion for the smaller duty cycles, reduced voltage and current stress on the active switches. Also, the dynamic performance of the HBC is analyzed in the closed-loop operation with fuzzy logic controller for the variations of supply voltages and load resistances. The simulation model of 400 V, 10 KW HBC is designed and implemented in MATLAB/Simulink, and the obtained results verify the better performance of HBC over boost converter.

The proposed converter is equivalent to the cascade connection of buck-boost converters, by using a single controlled switch between two stages. It is able to supply a lamp with good efficiency, high power factor and less %THD. In this paper, linear peak current mode control (LPCMC) technique is presented which is a simplified power factor correction technique for single-stage AC to DC converters, the advantages of this circuit include no multiplies are required and voltage sensing circuits. The implementation of this controller is made easy by the use of standard PWM control IC’s. From the AC mains, the IDBB converter will power the LED lamps which provides low ripple current through LED, less total harmonic distortion and high power factor.

The main aspiration of gun system is to propel projectile at desired range with high consistency and accuracy. Internal Ballistics (IB) plays a very vital role during design and development of gun systems. Initial temperature of charge system significantly affects gun IB performance. It is not always possible to conduct all gun firings at particular temperature conditions. Design of a temperature invariant charge system for large caliber guns is an important area of research in recent times. In this paper, a method is suggested for compensation of charge temperature effect on IB performance using Combustible Cartridge Case (CCC) physical parameters. A multivariate constrained optimization problem is defined for compensation of initial charge temperature effect on IB performance. The simulation results of this method show that the charge system can be converted into temperature independent by altering CCC physical parameters.

Analysis of protective structure’s effectiveness against Electromagnetic Interference (EMI) in a High Voltage Laboratories is very significant in today’s advancement in Science. This paper describes the shielding effectiveness (SE) of a Faraday cage with dimensions 6.2m X 5m X 8.2m for an environment comprising a High Voltage laboratory. However, simulation models are limited; the cage is scaled down by a factor of 50 and is simulated in EMPro© 3D EM simulation software. Finite Difference Time Domain (FDTD), computational technique is evolved as 3D EM field solver since it provides best memory efficient results for the considered structure. The obtained simulation results are compared with practical results and outcomes are recorded. The effects of cage’s thickness, and material on its SE are also determined. Average SE of 18 dB is obtained for our structure and the ways to further improve the SE are suggested.

In this study, Bi

Undoped and Mn 2+ doped ZnGa 2 O 4 phosphors were prepared by solution combustion method and characterized by XRD, SEM, luminescence and electron paramagnetic resonance (EPR) techniques. Based on XRD results, it is inferred that, strain in ZnGa 2 O 4 host lattice increases with incorporation of Mn 2+ ions in the lattice. Mn 2+ doping at concentration levels investigated, lead to significant reduction in the defect emission and this has been attributed to the formation of higher oxidation states of Mn ions in the lattice. Electron Paramagnetic Resonance studies confirmed that majority of Mn ions exist as Mn 2+ species and they occupy tetrahedral Zn 2+ site in ZnGa 2 O 4 lattice with an average hyperfine coupling constant, A iso ∼82 G.

Effect of active layer thickness on threshold voltage stability was studied. Threshold voltage instability was found to be minimum for an optimum thickness of 15 nm when operated under normal room light conditions. Influence of active layer thickness on individual contribution of hole and electron trapping effect to hysteresis was estimated. Hole and electron trap concentrations were found to exhibit different pattern of variation with thickness compared to each other. Film with 15 nm thickness exhibited minimum hole trapping and maximum electron trapping effect. This could be attributed to reduced grain boundary density and availability of large photogenerated carrier concentration at the dielectric/semiconductor interface. Along with electron trap, hole trap concentrations were also shown to be significantly influenced by photogenerated carrier concentration at the interface. For further increase in thickness, increase in hole trapping and reduction in electron trapping were observed again. This could be attributed to (a) increase in grain boundary density due to volume effect and (b) lesser number of photogenerated carriers at the interface due to limitations in exciton quenching length. Hole and electron trapping effect were suggested to be mutually affecting each other, depending on active layer thickness. Effect of active layer thickness was further confirmed with frequency and voltage dependent capacitance measurements.

The structural variations within monoclinic, tetragonal and cubic zirconia pellets with different amounts of yttria doping and its subsequent exposure to various proton, silver ion and gamma irradiation fluxes were investigated using photoluminescence spectroscopy. Upon ion irradiation color centers were produced at doses >10(15) ions/cm(2) resulting in purple coloration. The decrease in photoluminescence intensity was observed for proton irradiated pellets except for tetragonal zirconia (6YSZ: 6 mol% Y2O3 doped ZrO2). The anomalous behaviour in case of tetragonal zirconia may result from short range ordering of oxygen vacancies around Zr ions occurring in order to relieve the stress/lattice distortions associated with proton impingement. (C) 2014 Elsevier B.V. All rights reserved.

In this paper a new sliding surface is introduced with fuzzy current sliding mode (SM) control to overcome noise effect of differentiator in general current SM control. performance comparison of has been done on general SM control to the Fuzzy current SM control to Single phase AC/DC boost converter for achieving high power factor. This work is carried out in MATLAB/SIMULINK software. The converter is designed for 110V, 50 Hz AC input and 400V DC output.

This paper presents the design of an State-PID Feedback Controller (SFCPID) for a highly unstable non-linear system, magnetically suspended balanced beam (MSBB) and analysis of its effects. The modelling of Magnetically Suspended Balance Beam (MSBB) and design of Integral sliding mode controller are carried out using MATLAB/SIMULINK. The disturbance rejection of the controller is investigated and the stabilization performance of the State-PID Feedback Controller is compared with that obtained by a conventional state feedback controller with integral action when a disturbance force applied.

Rapid industrialization demands development of materials with better performance characteristics. When a material is subjected to an application, it is going to experience different conditions/environments, including, for example, high pressure, high temperature, hostile chemical environments, high mechanical stress, etc. Among the ones mentioned herein, the hostile chemical environment is a very important aspect. The nature and extent of interaction of a particular environment with a material and how it influences its physicochemical properties decide the hostile nature of the environment and this forms the subject matter of this chapter. In the beginning of this chapter, different hostile environments and their origins are described briefly. This is followed by synthesis and characterization of a variety of materials including stainless steel, nitrides, oxides, carbides, silicates, polymers, resins, etc. Important properties of these materials and how they vary upon interaction with different environments are discussed in detail. Techniques to monitor the extent of interaction of hostile environment with different materials are also discussed in this chapter. Along with this, the mechanism by which certain materials maintain their integrity and stability when exposed to different hostile chemical environments is also addressed.

Quantum yield of fluorescence (QYF) of widely used Rhodamine (RhB) dye in ethanol and water was observed to decrease rapidly with increase in temperature of the dye solutions, which was correlated to enhanced torsional motion of its flexible diethylamino groups. This is harmful for its use in high-average power dye lasers, pumped by copper vapour laser (CVL) or diode-pumped solid-state green laser (DPSSGL), in which bulk temperature of the dye solution was found to increase due to the heat generated by circulation pumps and non-radiative decay processes of excited dye molecules. The QYF of RhB dye in water was found to be not sensitive to temperature in the practical operating region 16–25°C of dye laser by adopting supramolecular route to form an inclusion complex of RhB with the container molecule cucurbit[7]uril (CB[7]).

Electrical measurements on copper phthalocyanine (CuPc)-based organic field effect transistors using SiO2 dielectric revealed hysteresis and threshold voltage instability to be due to the combined effect of both hole- and electron-trapping mechanisms, with the electron-trap density being higher than hole-trap density. Hysteresis was found to increase further after modifying the SiO2 surface with octadecyltrichlorosilane (OTS) while it reduced drastically after polystyrene (PS) modification. Individual contribution of holes and electrons to hysteresis and the cause of increased/reduced trapping of the same for interface modified devices were identified. The increase in hysteresis with OTS-modified devices was attributed to increase in hole-trap density arising from a larger grain-boundary density of CuPc films. Minimum grain-boundary density and efficient removal of trap centers at dielectric/semiconductor interface using PS modification resulted in minimum hysteresis. Comparison of hole- and electron-trap densities estimated for measurements under different ambient conditions, like high humidity conditions and oxygen flow, showed that hole-trap density increased with increase in humidity. Under oxygen flow, hysteresis, and hole-trap density were found to reduce considerably, which could be attributed to creation of excess holes that readily fill hole traps, thereby resulting in increased mobile carrier concentrations.

In this paper PV fed two stages DC-DC converter has been designed and implemented for home applications .In two stages first stage consists of step down converter and second stage consists of step up converter connecting in cascade manner and power is transfers through both the stages. Here boost stage for step-up the voltage given by buck converter which is step down stage and will give required voltage to operate the load. By using P&O based MPPT algorithm maximum power has been extracted from the PV system. The proposed model has been implemented by using MATLAB / Simulink and results are verified experimentally.

The density and molar volume of some phosphate glasses (xNa2O?(100-x)P2O5, x = 30, 35, 40, 45, 50); xB2O3?(1-x)NaPO3, x = 5, 10, 15, 20, 25; xNa2O?(30-x) K2O?10Al2O3? 25B2O3?35P2O5, x= 5, 10, 15, 20, 25) glasses were determined, in order to study their structure. The density of the glasses increased while their molar volume values decreases with the increase of sodium oxide content in phosphate glasses. The results obtained could be correlated to several factors such as the polarization, the field strengths and the ionic radii of the different incorporated cations.

We report morphological and ferromagnetic property control in ZnO nanorod structures by an optimum doping of Ni and Li. Nanostructures of Zn 0.97-xNi0.03LixO (x = 0, 0.03, 0.05, 0.08, and 0.10) are prepared by a solvothermal method. High aspect ratio (5-15) ZnO nanorods transform to particles (with 1-3 aspect ratio) influenced by 3 at. % Ni substitution in ZnO (Zn0.97Ni0.03O). It is remarkable to note that the Zn0.97Ni0.03O particles completely retain the nanorod shape with significantly increased aspect ratio (15-30) when 3 at.% Li ions are codoped in Zn0.97Ni0.03O (Zn 0.94Li0.03Ni0.03O). Li substitution also enhances ferromagnetism with largest magnetization (0.8 emu�g-1) observed for Zn0.94Li0.03Ni0.03O. For Li concentration >3 at.%, the aspect ratio as well as the magnetization decreased considerably. These experimental observations are explained by first-principles modeling. At low Li-on-Zn acceptor concentrations, the total magnetization is increased by lower Ni d-state populations, whereas at higher Li concentrations the population of ZnO host states decreases the ferromagnetism by induced magnetic moments on the oxygens. We discuss the significant implications of these results on the nanorods structures of room temperature ferromagnetic materials, which are expected to play pivotal role in developing spintronic devices. � 2010 American Chemical Society.

This work is aimed at discussing about the Java classes that are involved in implementing the Remote Method Invocation feature in Java. Remote Method Invocation feature is used in applications involving distributed processing. Applications based on distributed processing enable load sharing.

Determination of short start pressure (SSP) for gun system has always been of paramount interest for gun designers. In this paper, a generalised model has been developed for theoretical prediction of SSP for rifled gun system using dimensional analysis approach. For this, parameters affecting the SSP of the gun like rifling dimensions, driving band dimensions, material properties of driving band, projectile mass and diameter are taken into consideration. For a particular case of large caliber rifled gun system, the model is established using linear relations among dimensionless groups of parameters. The model has been validated by data available from the open literature.

As the power generating stations are located very far from the load centers, there is a necessity to transmit the power through the long transmission lines. The transmission efficiency and voltage profile are poor, due to the large amount of line losses and voltage drop. Thus to improve its performance, the generation of the power has to be done at the vicinity of load centers and is possible through the distributed generation (DG). The DG system consists of a boost converter which increases the dc input voltage obtained from an array of PV cells arranged on the solar panels.In this paper, the hybrid boost converter which is a high gain step-up dc-dc converter is modeled and analyzed for DG applications. The gain of this hybrid converter is D (duty ratio) times more than the normal boost converter and posses the advantages like less ripple current and high efficiency. Also the dynamic performance of the converters is compared in both open and closed loops from the simulation work carried out in MATLAB / Simulink environment.

Highly crystalline CePO4, CePO4:Tb3+, and CePO4:Dy3+ nanoleaves with monoclinic structure and dispersible in solvents such as water and methanol were prepared by a low temperature synthesis. Subsequently, these nanoleaves were incorporated into silica sols by the sol-gel method. Such nanoleaves incorporated into silica sols exhibit improved luminescence properties compared to silica sols directly doped with lanthanide ions. The observed difference in the luminescent properties of nanoleaves incorporated into silica sols and silica sols directly incorporated with lanthanide ions has been explained based on the different extent of energy transfer from Ce3+ to Tb3+/Dy3+ ions. The different extent of quenching of the excited-state of lanthanide ions due to OH groups from Si-OH linkages and water molecules, taking place in nanoleaves incorporated into silica sols compared to silica sols directly doped with lanthanide ions, is also responsible for the improvement in the luminescence properties. The present study will be quite relevant for developing biosensors for studying enzyme and protein activities based on luminescent silica sols. Refereed/Peer-reviewed

A sodium barium borosilicate glass matrix with a higher solubility of sulfate has been developed recently at Bhabha Atomic Research Centre for vitrification of sulfate bearing high-level nuclear waste. We report here the studies carried out to understand the influence of sulfate ion on the three-dimensional borosilicate network. Experiments were carried out with sodium barium borosilicate base glass samples loaded with varying amounts of SO 2- 4 (0-5 mol%). Phase separation studies on the samples revealed that as much as 3 mol% of SO 2- 4 can be loaded within the base glass without any phase separation, however, beyond this limit BaSO 4 (barite) crystallizes within the matrix. Thermal analyses of the samples indicated a shift in glass transition temperature from 534° (0 mol% SO 2- 4 ) to 495°C (3 mol% SO 2- 4 ) and it remained more or less unaltered afterwards even with high SO 2- 4 loading. A similar observation of structure stabilization was obtained from 29 Si MAS-NMR studies also, which showed that with 2 mol% of SO 2- 4 loading, the Q 2 :Q 3 ratio changed from 59:41 (for samples with 0 mol% SO 2- 4 loading) to 62:38 and it remained almost the same afterwards even with higher SO 2 4 - loading. 11 B MAS NMR patterns of the glass samples, however, remained unchanged with SO 2- 4 loading ((BO 4 ]:[BO 3 ]= 38:62). Based on 29 Si and 11 B MAS NMR studies, the authors propose two different ways of interaction of SO 2- 4 ions with the borosilicate network: (i) the network modifying action of SO 2- 4 ions with -Si-O-Si- linkages, at low SO 2- 4 ion concentration ( 2 mol%).

SnO2 nanoparticles dispersed in Eu3+ doped silica (SnO2-SiO2:Eu3+) were prepared at a low temperature (185 °C) in ethylene glycol medium. Transmission electron microscopy studies on as-prepared samples have established that SnO2 nanoparticles having size of 4.6 nm are uniformly covered by the SiO2 matrix. Significant extent of exciton mediated energy transfer between SnO2 and Eu3+ ions in heat treated SnO2-SiO2:Eu3+ samples has been attributed to the diffusion of Eu3+ ions from the SiO2 matrix to the near vicinity of SnO2 nanoparticles and its incorporation in the SnO2 matrix. On the other hand, very weak energy transfer exists for SnO2:Eu3+ nanoparticles heated at different temperatures due to the phase segregation of Eu3+ ions from the matrix.