Joint Spectrum Sensing and Resource Allocation for OFDM-based Transmission with a Cognitive Relay

In this paper, we investigate the joint spectrum sensing and resource allocation problem to maximize throughput capacity of an OFDM-based cognitive radio link with a cognitive relay. By applying a cognitive relay that uses decode and forward (D&F), we achieve more reliable communications, generating less interference (by needing less transmit power) and more diversity gain. In order to account for imperfections in spectrum sensing, the proposed schemes jointly modify energy detector thresholds and allocates transmit powers to all cognitive radio (CR) subcarriers, while simultaneously assigning subcarrier pairs for secondary users (SU) and the cognitive relay. This problem is cast as a constrained optimization problem with constraints on (1) interference introduced by the SU and the cognitive relay to the PUs; (2) miss-detection and false alarm probabilities and (3) subcarrier pairing for transmission on the SU transmitter and the cognitive relay and (4) minimum Quality of Service (QoS) for each CR subcarrier. We propose one optimal and two sub-optimal schemes all of which are compared to other schemes in the literature. Simulation results show that the proposed schemes achieve significantly higher throughput than other schemes in the literature for different relay situations.Comment: EAI Endorsed Transactions on Wireless Spectrum 14(1): e4 Published 13th Apr 201

Critical Analysis of Solutions to Hadoop Small File Problem

Hadoop big data platform is designed to process large volume of data Small file problem is a performance bottleneck in Hadoop processing Small files lower than the block size of Hadoop creates huge storage overhead at Namenode s and also wastes computational resources due to spawning of many map tasks Various solutions like merging small files mapping multiple map threads to same java virtual machine instance etc have been proposed to solve the small file problems in Hadoop This survey does a critical analysis of existing works addressing small file problems in Hadoop and its variant platforms like Spark The aim is to understand their effectiveness in reducing the storage computational overhead and identify the open issues for further researc

Eddy Current Testing of Zircaloy Wires

Fuel bundles for Rajasthan Atomic Power Reactor, consist of a cluster of 19 elements held together by zir-caloy and plates and spaced by wire helices on the six elements of the inner ring and alternative elements of the outer ring. As in the case of all other reactor mater-ials, the zircaloy wire also need be inspected 100% to avoid any defective part entering the reactor system. The zircaloy wire must be free from defects such as seams, internal voids, welded spots etc apart from the dimensio-nal and metallurgical requirements

EVALUATION OF SERUM PROLACTIN LEVEL IN CHRONIC KIDNEY DISEASE

ABSTRACTObjective: To study the association between chronic kidney disease (CKD) and hyperprolactinemia.Methods: The study was conducted in 50 patients with CKD admitted in K.A.P.Viswanatham Government Medical College/M.G.M. GovernmentHospital Tiruchirapalli, between August 2015 and December 2015, who were on maintenance dialysis. Fasting serum prolactin level was measuredin them to assess the presence of hyperprolactinemia. It was a prospective descriptive cross-sectional study. Quantitative determination of serumprolactin was done by fully automated bidirectionally interfaced chemiluminescent immunoassay.Results: Among the 50 CKD patients, 28 patients had raised serum prolactin levels. According to Statistical analysis of data using t-test, there is asignificant association between increased serum prolactin levels and presence of CKD.Conclusion: CKD is associated with increased serum levels of hormone prolactin (hyperprolactinemia).• Hyperprolactinemia could be detected in 56% of patients with CKDKeywords: Serum prolactin, Chronic kidney disease, Hypertension