Sensing and Sharing Schemes for Spectral Efficiency of Cognitive Radios

Increase in data traffic, number of users and their requirements laid to a necessity of more bandwidth. Cognitive radio is one of the emerging technology which addresses the spectrum scarcity issue. In this work we study the advantage of having collaboration between cognitive enabled small cell network and primary macrocell. Different from the existing works at spectrum sensing stage we are applying enhanced spectrum sensing to avoid probability of false alarms and missed detections which has impact on spectral efficiency. Later power control optimization for secondary users known as Hybrid spectrum sharing is used for further improvement of spectral efficiency. Furthermore, the failed packets of Primary users are taken care by high ranked relays which in turn decreases the average Primary user packet delay by 20% when compared between assisted Secondary user method and non-assisted Secondary user method.

Magnetic plateaus and jumps in a spin-1/2 ladder with alternate Ising-Heisenberg rungs: a field dependent study

We study a frustrated two-leg spin-1/2 ladder with alternate Ising and isotropic Heisenberg rung exchange interactions, whereas, interactions along legs and diagonals are Ising type. The ground-state (GS) of this model has four exotic phases: (i) the stripe-rung ferromagnet (SRFM), (ii) the anisotropic anti-ferromagnet (AAFM), (iii) the Dimer, and (iv) the stripe-leg ferromagnet (SLFM) in absence of any external magnetic field. In this work, the effect of externally applied longitudinal and transverse fields on quantum phases are studied. In both cases, we show that there exist two plateau phases at $1/4$, and $1/2$ of the saturation of magnetization. Due to the strong rung dimer formation, the system opens a finite spin gap for all the phases resulting in zero magnetization plateau in presence of a longitudinal field. The mechanism of plateau formation is analyzed using spin density, quantum fidelity, and quantum concurrence. In the (i) SRFM phase, Ising exchanges are dominant for all spins but the Heisenberg rungs are weak, and therefore, the magnetization shows a continuous transition as a function of transverse field. In the other three phases [(ii)-(iv)], Ising dimer rungs are weak and broken first to reach the plateau at $1/2$ of the saturation magnetization, having a large gap, which is closed by further application of the field. We use the exact diagonalization (ED) and the transfer matrix method (TM) to solve the Hamiltonian.Comment: 12 pages, 7 figure

Imprint of cyclone Phailin on water quality of Chilika lagoon

The very severe cyclonic storm Phailin, a category-5 hurricane, was developed over the north of Andaman and Nicobar Islands on 9 October 2013. Subsequently, it propagated towards north-northwest and made landfall at the Gopalpur coast, Odisha on 12 October1. Chilika lagoon, the largest brackish water lagoon in Asia, is in close proximity to Gopalpur

Development of Ultraviolet Spectrophotometric Method for Analysis of Lornoxicam in Solid Dosage Forms

Purpose: An ultraviolet spectrophotometric system was developed and validated for the quantitative determination of lornoxicam in solid dosage forms.Methods: Lornoxicam was dissolved in 0.01M NaOH and analysed using ultraviolet (UV) spectrophotometry. Various analytical parameters such as linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ) were determined according to International Conference on Harmonization (ICH) guidelines.Results: Absorbance maximum in 0.01M NaOH was 377 nm. Beer’s law was obeyed over the concentration range of 2 - 20 mg/ml with a correlation coefficient (r2) value of 0.999. Percent range of error was 0.344 and 0.261 at 0.05 and. 0.01 confidence limits, respectively. Intra- and inter-day precision (% RSD) at different concentration levels were < 2 %, indicating that the proposed derivative spectrophotometric method is highly reproducible during one run and between different runs; LOD and LOQ were 0.105 and 0.318 mg/ml, respectively signifying that it can be adopted for routine quality testing. Mean recovery was 100.82 % for tablets. Low values of % RSD indicate the reliability of the proposed methodConclusion: The proposed method is highly sensitive, precise, accurate, cost-effective, reliable and rapid for the estimation of lornoxicam in solid dosage forms.Keywords: Lornoxicam, UV Spectrophotometry, Quantitative determination, Solid dosage forms