Rates of change of total ozone column and surface relative humidity: seasonal variations over Dum Dum (22° 38′ N, 88° 26′ E)

This article presents a study of the seasonal variability of the rate of change of total ozone column (TOC) and the rate of change of surface relative humidity (RH) over Dum Dum (22° 38′ N, 88° 26′ E) during different seasons of the period 1997–2005. The rate of formation of TOC was a maximum during the pre-monsoon and winter seasons and the rate of decrease of TOC was a maximum during the monsoon and post-monsoon seasons throughout the period of study. The rate of increase of surface RH was a maximum in the pre-monsoon season and the rate decreased during the other seasons. At the monsoon and post-monsoon seasons the rate of decrease of TOC increased with the rate of decrease of surface RH.     

Analysis of arbitrarily shaped microstrip patch antennas using the Sommerfeld formulation

Triangular patch modeling is used for analysis of arbitrarily shaped microstrip patch antennas over a single lossy dielectric medium. Since the Sommerfeld formulation is used, both the single dielectric layer (over which the microstrip patch is located) and the ground plane are considered to be infinitely wide. Typical numerical results are presented for rectangular, circular, semicircular, pentagonal, and triangular patch antennas. © 1992 John Wiley & Sons, Inc.     

Impact of Li<Superscript>3+</Superscript> ion irradiation on magnetic properties of Mn doped ZnO: correlation with defects and structural property

Present work aims to study the impact of 50 MeV Li³⁺ ion irradiation on magnetic properties and their correlation with the substitutional incorporation of Mn at Zn site (Mn_Zn) and defects in Mn:ZnO (Mn doped ZnO). 2 at% Mn:ZnO has been synthesized by solid-state reaction method and irradiated with fluences 10¹², 10¹³ and 10¹⁴ ions/cm². The concomitant changes have been probed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and magnetization measurements. XRD patterns indicate single-phase nature of the samples and Mn_Zn nicely varied with fluence of irradiation. Temperature dependent dc and ac magnetization (M-T) measurement reveals a minor presence of spin glass nature or superparamagnetism (SPM) though all of the samples are strongly intrinsically ferromagnetic and field dependent magnetization (M-H) measurement actually confirms this observation. It is noteworthy to observe that the ordering of spins and the magnetic parameters viz. saturation magnetization (M_S), remnant magnetization (M_R) and coercivity (H_C) can be tuned by fluences of irradiation. Finally, proportion of defect [particularly zinc vacancy (V_Zn)] and Mn_Zn seems to dictate the trend of variation of magnetization (M_S and M_R). Temperature dependent ac magnetization measurement and magnetic relaxation measurement actually detect a weak spin glass nature of the samples and eliminate the possibility of SPM.     

Dynamic background modeling using intensity and orientation distribution of video sequence

Multimedia Tools and Applications - Moving object detection in a video sequence is a challenging task in presence of dynamic background. In this paper, we propose a novel approach for background...     

Two-Element Quad-Band MIMO Antenna Employing Meandered Arm Printed Inverted–F Antenna

This article proposed a compact dual-element MIMO (multiple-input-multiple-output) antenna system working in 1.575 GHz (Global Positioning System)/4.5 GHz (5G)/5.8 GHz (Wireless Local Area Network)/6.4 GHz (Satellite communication) with relatively high isolation. The proposed antenna element consists of compact inverted-F antenna with meandered arm. One side of the T-shaped monopole antenna is extended and meandered while the other side is grounded to form the IFA structure. Meandering of the arm is responsible for the quad-band response. The proposed structure is simulated and fabricated on a FR4 substrate with an overall dimension of (0.23 λ₀?×?0.09 λ₀?×?0.004 λ₀) and edge-to-edge separation of the two patches is 0.04 λ₀, where λ₀ is the wavelength at lower resonating frequency (1.575 GHz) of the proposed antenna. The high isolation is achieved by incorporating two inverted L-shaped strips and a narrow slot in the ground plane. Envelope correlation co-efficient (ECC) and channel capacity loss (CCL) are within their acceptable limits. Other different diversity parameters are evaluated and the results are satisfactory for MIMO applications.

     

Video error concealment through 3-D face model

Multimedia Tools and Applications - All current state-of-the-art video error concealment schemes conceal the lost area through the reconstruction of 2-D patches. Reconstructed corrupted areas in...     

Electromagnetic radiation and scattering from finite conducting anddielectric structures: surface/surface formulation

An efficient and accurate numerical procedure for the analysis of the electromagnetic scattering and radiation from arbitrarily shaped, composite finite conducting and dielectric bodies is proposed. A set of coupled electric field integral equations involving surface equivalent electric and magnetic currents is used. The coupled integral equations are solved through planar triangular patch modeling and the method of moments. Two separate, mutually orthogonal vector functions for each edge connecting a pair of triangular patches have been developed. Numerical results for disk/cone and cylinder/cone structures are compared with other available data. Limited comparison with experimental data has also been made     

Enhanced efficiency of phenothiazine derivative organic dye‐sensitized ionic liquid solar cells on aging

We have used electrochemical impedance to investigate the improvement in photovoltaic performance in aging of ionic liquid dye‐sensitized solar cells using a high‐absorption coefficient organic dye (2E)‐2‐cyano‐3‐(5‐(5‐((E)‐2‐(10‐(2‐ethylhexyl)‐10H‐phenothiazin‐7‐yl)vinyl)thiophen‐2‐yl)thiophen‐2‐yl)acrylic acid, which is in contrast to N719‐based devices. It was found that the enhancement is due to reduced recombination of the photoexcited electrons. The decreased recombination plausibly originates from molecular re‐orientation along with cation adsorption, with Fourier transform infrared spectra lending support to the former mechanism. After aging, the photovoltaic device using the organic dye outperforms the counterpart by the ruthenium complex dye and achieves an impressive efficiency of 5.6% under AM 1.5 100 mW/cm² illumination. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and Superior Optical‐Limiting Properties of Fluorene‐Thiophene‐Benzothiadazole Polymer‐Functionalized Graphene Sheets

A polymer based on fluorene, thiophene, and benzothiadazole as the donor–spacer–acceptor triad is covalently coupled to reduced graphene oxide (rGO) sheets via diazonium coupling with phenyl bromide, followed by Suzuki coupling. These polymer–graphene hybrids show good solubility in organic solvents, such as chloroform, tetrahydrofuran (THF), toluene, dichlorobenzene, and N,N‐dimethylformamide (DMF), and exhibit an excellent optical‐limiting effect with a 532‐nm laser beam. The optical‐limiting threshold energy values (0.93 J cm^?2 for G–polymer 1 and 1.12 J cm^?2 for G–polymer 2) of these G–polymer hybrids are better than that of carbon nanotubes (3.6 J cm^?2).