Enhancement of light absorption using Nanoparticles Embedded Double layer Anti-Reflection Coating

The formation of nanoparticles embedded composite materials is a means for engineering the electrical and optical properties of thin films. This paper proposes the use of gold and silver nano-particles(NPs) to fine tune the effective index of two dielectric layers towards anti-reflection coating applications. Here, the upper layer is MgF2 (magnesium fluoride) and the lower layer is PMMA (Polymethylmethacrylate). The effect of embedding the nano-particles in the PMMA layer on the transmission spectrum is studied while tuning the concentration (volume fraction) and size of particles. With the increase in the size of the nano-particles there is a red shift in the transmission dip. On varying the nano-particle size the peak absorption can be shifted to the desired wavelength. Considering 50 nm silver nano-particle with the volume fraction ranging from 0.001 to 0.05, maximum transmission of light is observed under lower wavelength range of visible spectrum across the novel structur

Dimming Consideration for OFDM-Based Visible Light Communications

In the field of indoor wireless networks, visible light communications would be contributing a vital role in the future. This paper investigates the performances of data transmissions using visible light based on unipolar orthogonal frequency division multiplexing (OFDM) and discusses possible approach for light dimming. Asymmetrically clipped optical OFDM (ACO-OFDM) is considered as a unipolar modulation scheme for intensity modulation with direct detection (IM/DD) on which visible light communications is based. This modulation can incorporate light dimming while not corrupting the communication link since, compared to the traditional DC biased optical OFDM (DCO-OFDM), ACOOFDM noise clipping component does not fall on data carrying subcarrier. To create more dimming levels pulse width modulation (PWM) is proposed to be used in conjunction with ACO-OFDM.Keywords: Orthogonal frequency division multiplexing (OFDM), light emitting diode (LED), signal clipping, visible light communication.Cite as:Sunil Deka, Poompat Saengudomlert, Sunandan Baruah "Dimming Consideration for OFDMBased Visible Light Communications", ADBU J.Engg.Tech., 2(1)(2015) 0021101(5pp

L'origine des Moëres de la plaine maritime de Flandre

Water-soluble ionic constituents (Cl-, NO3-, SO42-, Na+, NH4+, K+, Mg2+ and Ca2+) of PM2.5 were measured using Ambient Ion Monitor coupled-to Ion Chromatography (AIM-IC) with a time resolution of one hour at Ahmedabad (an urban location in a semi-arid region of western India) during summer and winter to study the diurnal and seasonal variations. Maximum abundances of most of the species were observed during afternoon hours in summer, whereas minimum concentrations were found during winter at the same local time. During summer, the concentration levels of most of the constituents in a diurnal cycle are largely influenced by variations in the ambient relative humidity. During winter, the emission strength and boundary layer dynamics impact the diurnal cycle. Secondary inorganic species like NH4+, NO3- and SO42- exhibit significant differences in their relative abundances during winter and summer. Four factors have been derived by Positive Matrix Factorization (PMF) analysis of the water-soluble ionic constituents. These are secondary, sea-salt, mineral dust sources, while the fourth factor is associated with K+, which is likely to be due to emissions related to biomass burning

No-patch 23-gauge vitrectomy under topical anesthesia: A pilot study

A pilot study was designed to evaluate the safety and efficacy of 23-gauge vitrectomy under topical anesthesia. Five eyes of five patients underwent 23-gauge sutureless vitrectomy under topical anesthesia with a pledget soaked in 0.5% proparacaine hydrochloride anesthetic, for vitreous hemorrhage (four eyes), epiretinal membrane (one eye). Subjective pain and discomfort were graded using a visual analogue chart from 0 (no pain or discomfort) to 4 (severe pain and discomfort). At the end of surgery no patch was applied and patients were given dark glasses. Patients underwent an immediate postoperative assessment, followed by next day and one week postoperative evaluation. Four patients had Grade 0 pain during the surgery. One patient had Grade 1 pain during the placement and withdrawal of the micro cannulas. The surgical outcomes were favorable. 23-gauge vitrectomy under topical anesthesia is safe and effective in selected cases. Further study is recommended to validate the outcome of this study

A Critical Review on the Estimation Techniques of the Solar PV Cell’s Unknown Parameters

To meet the exponentially growing demand for clean and green energy, the solar photovoltaic (PV) system’s importance is increasing day by day, for which PV modeling is considered to be one of the most important work in the current state-of-the-art methods. To effectively model a PV system, accurate PV parameter estimation is of the utmost importance. In line with this, although the values of some of the parameters are provided in the manufacturer’s datasheet, the values of unknown parameters, such as shunt resistance, series resistance, the diode ideality factor, photo-generated current and diode saturation current, are not provided. To estimate these values a lot of algorithms are already reported in the literature. After careful observation of all the reported algorithms, a few best-reported algorithms are identified and their performances are compared with respect to accuracy, convergence issues, computational complexity and thermal stability. All kind of algorithms, such as numerical, analytical and evolutionary algorithms, are considered in this study, and only the best reported algorithms are considered for the comparison