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The present work describes a model simulation study of electrowetting on a dielectric surface (EWOD)-based liquid lens using three distinct insulating liquids, namely, silicone oil, n-hexadecane, and n-tetradecane. The model essentially consists of a cylindrical chamber with a typical inner diameter of 3.0 mm and a height of 1.0 mm coated with two different hydrophobic dielectric surfaces, parylene-C and teflon- AF. With a 21.4 mM KCl solution employed as a conducting liquid, the interfacial layer between the two immiscible liquids was found to be modulated precisely for a critical biasing voltage, V > 90 V, switching the curvature profile from diverging to converging type. Moreover, the effects of applied voltage and dielectric layer thickness on this changeover and focal lengths were discussed for a given set of aforesaid pairs of immiscible liquids. Our simulated results and model analyses provide useful insights on the means of experimental strategies, scope, and limitations towards realization of industrial-grade designs and assets. [ABSTRACT FROM AUTHOR]

We report on the nature of charge-neutral exciton emission decay, exciton-trion conversion as well as their phonon coupling in exfoliated WSe2 nanosheets subjected to ~ 1.3 MeV energetic γ-photons. Steady-state photoluminescence (PL) spectra, upon deconvolution, showed prominent emission peaks at ~ 680 nm, ~ 712 nm, and ~ 730 nm and ascribed to 2s, and 1s excitons and trions respectively, while the chalcogen vacancy (VSe) mediated defect emission peak found at ~ 790 nm. From the X-ray photoelectron spectroscopy (XPS) analysis, we noticed a clear shifting of the fundamental peaks due to W and Se toward higher binding energy values and were attributed to the radiation-induced alteration in the oxidation states locally, taking advantage of the manifestation of point defects/vacancies. Moreover, the time-resolved PL spectra signify an anomalous variation in the fast parameter (0.4–0.86 ns), and with slow parameter (2.46–3.82 ns) getting slower with increasing γ-dose. A slight variation in the exciton-phonon coupling factor is noted with Se-ph < 1 indicating a weaker interaction and featuring maximal envelope over all the phonon replica near the zero-phonon line. In contrast, trion-phonon coupling factor, St-ph > 1, or < 1 depending on its spin degeneracy (ζ = 2 s + 1; with 2, for s = 1/2 and 4 for s = 3/2). The highest St-ph value determined was ~ 1.82 ± 0.2 which declines monotonically with increasing dose but remained greater than unity up to a γ-dose as high as 96 kGy. The implication of trion-phonon coupling has immense scope in nano-photovoltaics, and nano-electronics as well as heat sinks in nanogenerators. [ABSTRACT FROM AUTHOR]

The classical droop method is widely used in AC microgrid (MG) for sharing load among distributed generations. Apart from interlinking the DC sources, the voltage source inverters control the power flow from renewable energy sources. Thus, they contribute toward the demand side management (DSM) by employing the voltage reduction method (VRM). The VRM is widely utilized in the distribution system of the grid network, its concern is to reduce the voltage in a suitable manner so as to maintain the voltage within the acceptable limits, leading to power savings. However, the application of VRM in the stand-alone MG is very scarce. Thus, this paper attempts to apply VRM so as to achieve not only the benefits pertaining to voltage control but also power savings from DSM. The voltage–current (V–I) droop characteristics are of paramount importance for DSM using VRM to increase the number of consumers during high demand of electrical energy. One of the important contributions is modification of the P–f droop control to maintain the frequency of the MG within the permissible limit while applying VRM. In addition, the behavior of three-phase to ground fault is being investigated and competency of the control algorithm is validated through implementation on 5 bus stand-alone microgrid system and further, it is tested on IEEE 14 bus test system. The efficacy of the proposed approach is established through the comparison of the results with those for classical voltage and frequency-based droop schemes bereft of communication ability. The control mechanism has also been validated in real-time using schematic editor of Typhoon virtual HIL 402. [ABSTRACT FROM AUTHOR]

In the current research, we report on the synthesis of WO3/GQD system as a heterogeneous catalyst for the transesterification of waste cooking oil into biodiesel using methanol. The characterization of the prepared catalyst was done by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscope (TEM), energy-dispersive X-ray (EDX), Fourier transform-infrared spectroscopy (FT-IR) techniques, and Brunauer-Emmett-Teller surface area measurement. To study the effect of process variables such as methanol to oil ratio, reaction temperature, and time, we have employed response surface methodology (RSM) based on Box-Behnken design (BBD). The suitability of the predicted model was verified, and the average biodiesel yield of (96.8 ± 0.16%) was reported at optimal reaction condition of 1:6 oil to methanol ratio, 70 °C reaction temperature, 2 wt% catalyst loading, and 3.5 h reaction time. Biodiesel was characterized using proton nuclear magnetic resonance (1H NMR) and carbon nuclear magnetic resonance (13C NMR) techniques, and fatty acid methyl ester composition was determined using gas chromatography-mass spectrometry (GC-MS). Fuel properties of the biodiesel obtained comply with ASTMD6751 biodiesel standards. The kinetics of transesterification was studied and found to follow pseudo-first order. The results showed the rate constant ranging from 0.0028 to 0.007 min−1, activation energy (Ea) of 55.92 kJ mol−1, and frequency factor (A) of 1.72 × 106 min−1. [ABSTRACT FROM AUTHOR]

The recent developments in embedded system design and communication technologies popularized the adaption of the cyber-physical system (CPS) for practical applications. A CPS is an amalgamation of a physical system, a cyber system, and their communication network. The cyber system performs extensive computational operations on the data received from the physical devices, interprets the data, and initiates effective control actions in real-time. One such CPS is the smart grid CPS (SG-CPS) consisting of physical devices with diverse communication requirements, and intermediate communication networks. Thus, reliable communication networks are paramount for the effective operation of the SG-CPS. This paper is an elaborate survey on the communication networks from the perspective of the SG-CPS. This paper presents the state-of-art communication technologies that can meet the communication requirements of the various SG-CPS applications. The communications standards and communication protocols are also comprehensively discussed. A systematic mapping among communication technologies, standards, and protocols for various SG-CPS applications has been presented based on an extensive literature survey in this paper. Furthermore, several challenges, such as security, safety, reliability and resilience, etc., have been addressed from SG-CPS's perspective. This work also identifies the research gaps in the various domains of the SG-CPS that can be of immense benefit to the research community. [ABSTRACT FROM AUTHOR]

This paper presents a multifunctional scheme to reinforce the protection of Extra High Voltage (EHV)/Ultra High Voltage (UHV) transmission lines. The proposed scheme employs d–q transformed traveling waves and the time of incidence of first traveling waves at both ends of the line for fault detection and location respectively. Furthermore, the faults are classified using energy values of approximation coefficients and the phasors are estimated from the approximation coefficients. The traveling waves are nothing but detail coefficients. The detail and approximation coefficients are obtained using discrete wavelet transform multi-resolution analysis (DWT-MRA) of the 3-ɸ current signals. The proposed algorithm detects and locates a fault within a quarter cycle. The proposed scheme has been implemented on a two-bus and the WSCC-9 bus systems in EMTDC/PSCAD software to verify the efficacy and reliability. Also, it has been realized on a laboratory model of an EHV transmission line of length 200 km using NI cDAQ-9178 chassis, NI-9227 current sensor card, and LabVIEW software. The simulation and hardware results evince the protection reinforcing property of the proposed multifunctional scheme. [ABSTRACT FROM AUTHOR]

In this paper, a detailed study of the modes of hidden failures (HFs) in protection systems is carried out, and probabilistic modeling methodology is used for analyzing the impact of HFs on the power system cascading events. Further, the probabilistic model of HFs based on impedance and line power flow is hypothesized for qualitative evaluation of HF's impact on power system cascading disruptions. Numerous case studies have been carried out on the IEEE-118 bus system to assess the effect of HFs by fitting the probability model of line outage based on impedance and power flow. This analysis has successfully identified the most sensitive transmission lines in the network which are having the highest tendency to trip in case of protective system HFs. Also, it has been shown that the probability of major blackouts will be reduced to a more significant extent if the self-checking and monitoring features are incorporated into digital relays. The qualitative analysis of protection system HFs could be helpful in planning, service and maintenance scheduling of a power system as well as determining the locations where an investment warrants the protection system reliability. [ABSTRACT FROM AUTHOR]

Rare earth oxide (Tb:GdO and Eu:GdO) nanophosphors are exploited through spectroscopic and microscopic tools with special emphasis on D- F mediated radiative emission and Raman active vibrational modes. Powder X-ray diffraction measurements have revealed cubic crystal structure of the nanosystems and with an average crystallite size varying between ~3.2 and 4.8 nm. Photoluminescence (PL) spectra of Tb doped systems signify intense blue-green (~490 nm) and green (~544 nm) emissions mediated by D → F and D → F transitional events; respectively. In the PL responses of Eu doped nanoparticle systems, we also identify magnetically-driven D → F (~591 nm) and electrically driven D → F (~619 nm) radiative features which seem to improve with increasing doping level. However, the magnitude of Judd-Ofelt (J-O) intensity parameters ( Ω ), is significantly lowered for the high doping cases. Raman spectra of the undoped and RE doped systems exhibited several A and F modes in the range of Raman shift ~100-600 cm. In the Raman spectra, the peaks located at ~355 cm are assigned to the mixed mode of F + A , the line width of which was found to increase with RE doping. Moreover, owing to the enhanced defect concentration in the doped systems than its undoped counterpart, we anticipate a faster phonon relaxation and consequently, a suppression of phonon lifetime in the former case. [ABSTRACT FROM AUTHOR]

Power system planning is a capital intensive investment-decision problem. The majority of the conventional planning conducted since the last half a century has been based on the least cost approach, keeping in view the optimization of cost and reliability of power supply. Recently, renewable energy sources have found a niche in power system planning owing to concerns arising from fast depletion of fossil fuels, fuel price volatility as well as global climatic changes. Thus, power system planning is under-going a paradigm shift to incorporate such recent technologies. This paper assesses the impact of renewable sources using the portfolio theory to incorporate the effects of fuel price volatility as well as CO emissions. An optimization framework using a robust multi-objective evolutionary algorithm, namely NSGA-II, is developed to obtain Pareto optimal solutions. The performance of the proposed approach is assessed and illustrated using the Indian power system considering real-time design practices. The case study for Indian power system validates the efficacy of the proposed methodology as developing countries are also increasing the investment in green energy to increase awareness about clean energy technologies. [ABSTRACT FROM AUTHOR]

The response of a typical ferrofluid (FF) lies in its explicit property of chain formation of magnetic nanoparticles. The most significant magneto-optic (MO) and magneto-viscous (MV) effects of FF are attributed to chaining effect. In the present research, an effort was made to analytically justify the dependence of the structure evolution of FFs on different measurable parameters involved in MO and MV effects. The problem is treated with the help of dimensional analysis and an empirical relation is formulated relating the equilibrium chain length with Verdet coefficient (constant), particle diameter, viscosity of the carrier fluid, particle density, magnetization and shear rate. The formulated relation of chain length is supported by error analysis to yield the uncertainty in the result. The maximum uncertainty in four sets of data is found as ∼0.75. [ABSTRACT FROM AUTHOR]

Present work reports a comparative study of spectroscopic and magneto-optic properties of FeO based ferrofluids prepared with two different carrier fluid namely milli-Q-water and kerosene. The ferrofluids are labelled as FFW and FFK respectively. Both ferrofluids are subjected to γ-irradiation of dose: 2,635 Gy. Transmission electron microscopy and dynamic light scattering studies reveal that γ-photon interaction could lead to substantial growth of the dispersed nanoparticles of ferrofluids. In case of FFW, particle sizes are ~9 nm (pristine) and ~48 nm (irradiated) whereas, in FFK unirradiated particles of size ~9 nm show growth to ~18 nm after the irradiation. The role of different physical parameters (viz. viscosity, density) of carrier fluid on the growth process is considered in this regard. Viscosity of the carrier fluid is found noteworthy in the measurement of Faraday rotation response of the ferrofluids. In addition to low viscosity of water, irradiation induced particle growth as well as improved size distribution with larger particles leads to a comparatively larger enhancement of Faraday rotation of FFW than that of FFK. Consequently, as a result of γ-irradiation, Verdet constant is modified by ~70 % in the former case and by ~60 % in the latter case. [ABSTRACT FROM AUTHOR]

Inexpensive production and characteristic magnetoconductance fluctuation of Ge-supported stable graphene/graphene oxide layers are being reported. The changeover from graphite to graphene oxide structure during synthesis was evident from X-ray diffraction patterns whereas development of mono and bilayer graphene/graphene oxide was confirmed by electron microscopy studies. Responding to applied magnetic fields (up to 0.3 T), the Ge-supported graphene layers are shown to exhibit prominent magnetoconductance steps and are attributed to the alteration of Landau levels across the Fermi surface. While low-cost fabrication process is attractive for large scale production, the advantage of short synthesis time and understanding magneto-transport mechanism would find relevance in graphene-based nanodevices and circuits. [ABSTRACT FROM AUTHOR]

Barbules of the peacock feather have been used as the natural template for developing assemblies of zinc oxide (ZnO) nanospheres. The different colored barbules consisting of various photonic crystals (extracted from eye-pattern) were characterized in terms of the stop-bands identified in the respective Reflectance spectra. The stop-bands of the photonic crystals are found to get red-shifted after the loading of ZnO nanospheres and was reasoned to the modification of photonic band gap. The ZnO nanosphere decorated barbules show well defined photoluminescence response with dominant defect related emission of ZnO. The artificially grown inorganic structures on natural templates form a basis of new hybrid system that can help in exploiting photonic band gap engineering and light wave modulation with high selectivity. [ABSTRACT FROM AUTHOR]

In the present work, we show that Mach-Zehnder interferometry (MZI) can be an asset to explore the birefringence properties of semiconductor nanocrystallites (NCs). A 0.352 μm thick polymer containing ZnSe–NCs (size dispersion: 2.5×1010/cm2) was kept on either of the arms of the MZI (λ=632.8 nm) and the phase angles were measured at the output, corresponding to three selected spots of the specimen. Owing to the non-resonant excitation led transient polarization in the NCs, strong optical Kerr-signals were detected with Kerr coefficient values ~1.87 × 10-9 m/V2. The approach may be extended to other optically isotropic nanoscaled materials having a center of inversion including liquid crystals. [ABSTRACT FROM AUTHOR]

Hydroxyl free zinc oxide nanorods have been synthesized by a catalyst free surfactant based one-step solid state reaction process. The powder X-ray diffraction studies reveal well defined wurtzite peaks due to crystalline ZnO, while optical absorption spectra represent prominent exciton absorption and remarkable blueshift in the onset of absorption. As predicted by transmission electron microscopy, the ZnO nanorods are ∼100 nm long and of ∼20 nm dia. Further, luminescence aspects of such nanorods are studied for possible deployment in optoelectronics devices. [ABSTRACT FROM AUTHOR]

Polymer embedded cadmium sulfide nanoparticles/quantum dots were synthesized by a chemical route using polyvinyl alcohol (lmw) as the desired matrix. In an attempt to measure the electrical properties of nano-CdS/Ag samples, we propose that contribution from surface traps are mainly responsible in determining the I∼ V and C∼ V characteristics in high frequency ranges. To be specific, beyond 1.2 MHz, the carrier injection from the trap centers of the embedded quantum dots is ensured by large current establishment even at negative biasing condition of the junction. The unexpected nonlinear signature of C∼ V response is believed to be due to the fact that while trying to follow very high signal frequency (at least 10-3 of recombination frequency), there is complete abruptness in carrier trapping (charging) or/and detrapping (decay) in a given CdS nanoparticle assembly. The frequency dependent unique role of the trap carriers certainly find application in nanoelectronic devices at a desirable frequency of operation. [ABSTRACT FROM AUTHOR]

The pH of the dispersing media has an influential role on the optical and radiative features of quantum particles/dots (QDs). Herein, we report size dispersity and luminescence response of sodium dodecyl sulphate (SDS)-coated MnSe QDs dispersed in extreme natural extracts. The hydrothermally processed QDs exhibited wutzite phase and numerous Raman active modes as revealed through the X-ray diffraction and Raman spectroscopy studies; respectively. Of varied pH (typically, from 2.5 to 9), distinctly different extracts were derived from starfruit, sugarcane, chilli, and neem leaves available locally. The hydrodynamic size of the QDs experiences a declining trend with increasing pH, with dispersing media being a buffer solution or a natural extract. Zeta potential makes a clear transition from the positive to the negative values, as one moves from a low (acidic) to high (basic) pH of the natural extracts, and subsequently, the isoelectric point (IEP) of the QDs in a medium has been predicted at pH 6.3. Whereas a more acidic medium offered a relatively lowered luminescence profile, the extracts of high pH ensured an intense blue–violet emission of the QDs located at ~ 428 nm along with defect-mediated peaks, expected at relatively higher wavelengths. Furthermore, the acidic environment tends to suppress both near band edge and defect-mediated emissions substantially. The optical stability of surfactant-coated QDs would find immense value in the areas of nano-bio interface applications, such as nano-bioconjugation, bio-imaging, and drug formulation in nano-medicine. [ABSTRACT FROM AUTHOR]

In this work, we report on structural, optical, photocatalytic and nitrogen adsorption-desorption characteristics of WS2 nanosheets developed via a hydrothermal route. X-ray diffraction (XRD) studies have revealed a hexagonal crystal structure, whereas nanodimensional sheets are apparently observed in scanning and transmission electron microscopy (SEM and TEM) micrographs. As compared to the bulk counterpart, the WS2 nanosheets exhibited a clear blue shift. Through Brunauer-Emmett-Teller (BET) surface area analysis, average surface area, pore volume and pore size of the NSs were calculated as 211.5 m2g-1, 0.433 cc g-1 and 3.8 nm, respectively. The photocatalytic activity of the WS2 nanosheets was also examined with malachite green (MG) as the target dye under both UV and day light (visible) illumination conditions. Accordingly, a degradation efficiency as high as 67.4 and 86.6% were witnessed for an irradiation time duration of 60 min. The nano-WS2 systems have immense potential in optoelectronics, solid-lubrication and other next generation elements. [ABSTRACT FROM AUTHOR]