Cooperative Access in Cognitive Radio Networks: Stable Throughput and Delay Tradeoffs

In this paper, we study and analyze fundamental throughput-delay tradeoffs in cooperative multiple access for cognitive radio systems. We focus on the class of randomized cooperative policies, whereby the secondary user (SU) serves either the queue of its own data or the queue of the primary user (PU) relayed data with certain service probabilities. The proposed policy opens room for trading the PU delay for enhanced SU delay. Towards this objective, stability conditions for the queues involved in the system are derived. Furthermore, a moment generating function approach is employed to derive closed-form expressions for the average delay encountered by the packets of both users. Results reveal that cooperation expands the stable throughput region of the system and significantly reduces the delay at both users. Moreover, we quantify the gain obtained in terms of the SU delay under the proposed policy, over conventional relaying that gives strict priority to the relay queue.Comment: accepted for publication in IEEE 12th Intl. Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt), 201

Recurrence Relations for Moments of Dual Generalized Order Statistics from Weibull Gamma Distribution and Its Characterizations

In this paper, we establish explicit forms and new recurrence relations satisfied by the single and product moments of dual generalized order statistics from Weibull gamma distribution (WGD). The results include as particular cases the relations for moments of reversed order statistics and lower records.We present characterizations ofWGD based on (i) recurrence relation for single moments, (ii) truncated moments of certain function of the variable and (iii) hazrad function

The preparation and characterization of chitosan/poly (vinyl alcohol) blended films : mechanical, thermal and surface investigations

In this study, blends of chitosan (CS) and polyvinyl alcohol (PVA) (CS/PVA) having various proportions were prepared and characterized by universal mechanical tester, the differential scanning calorimetry (DSC) and contact angle measurements. Studying the mechanical properties of the films showed that blending improved the tensile strength, which increased with increasing PVA content up to 40% while the elongation% at break of the blends was decreased compared to that of the pure components. The obtained results of DSC suggested that some interaction between chitosan and PVA mostly took place. Static water contact angle measurements showed an improvement in the wettability of the obtained films

A modified multiview video streaming system using 3-tier architecture

In this paper, we present a modified inter-view prediction Multiview Video Coding (MVC) scheme from the perspective of viewer's interactivity. When a viewer requests some view(s), our scheme leads to lower transmission bit-rate. We develop an interactive multiview video streaming system exploiting that modified MVC scheme. Conventional interactive multiview video systems require high bandwidth due to redundant data being transferred. With real data test sequences, clear improvements are shown using the proposed interactive multiview video system compared to competing ones in terms of the average transmission bit-rate and storage size of the decoded (i.e., transferred) data with comparable rate-distortion

Convenient Synthesis of Some New Bi-heterocycles conataining 3-Aminoquinazolin-4(3H)-one and 1,2,4-Triazole moieties

Dicarboxylic acids, thiosemicarbazides and methylanthranilate reacted to give methyl-2-(3-(5-mercapto-4-s-1,2,4-triazol-3-yl)-3-oxoalkylamino)benzoates 4. The laters, cyclized with hydrazine hydrate to give 3-amino-2-((5-mercapto-4 substitued-1,2,4-triazol-3-yl)alkyl)quinazolin-4(3H)-ones 5 which expected to have biological effects

Solar Energy Conversion and Storage: Rose Bengal-Triton X-100 by Photogalvanic Cell

Photogalvanic cells are photoelectrochemical devices involving ions as mobile charges moving in solution through diffusion process. These cells are capable of solar power generation at low cost with inherent storage capacity. This property of photogalvanic cell needs to be exploited as this technology is cleaner and promising for application in daily life. In our work, Rose Bengal is used as photosensitizer with oxalic acid as reductant and triton as surfactant for photoelectrochemical conversion of solar energy into electrical energy. The photopotential and photocurrent generated were 289.0 mV and 29.1 µA, respectively. The maximum power of the cell was 8.409 µW. The observed conversion efficiency was 0.023 % and fill factor was determined as 0.293 against the maximum theoretical value 1.0. The photogalvanic cell can work for 45.0 min in dark after irradiation for 21.0 min, i.e. the storage capacity of the photogalvanic cell is 45 min. The effect of different parameters on electrical output of the cell was studied and a mechanism has also been proposed for the generation of photocurrent in photogalvanic cell. Keywords: Rose Bengal; Oxalic acid; Triton; Conversion efficiency; Storage capacity; Photocurrent

Improvement of Heavy Oil Recovery by Nonionic Surfactant/Alcohol Flooding in Light of the Alkane Carbon Number and Interfacial Tension Properties

ACKNOWLEDGMENTS The Egyptian authors were supported by the Science, Technology & Innovation Funding Authority (STDF) under grant 30894. The authors from the UK would like to acknowledge the financial support from an Institutional Links grant, ID 352343681, under the Newton-Mosharafa Fund partnership. The grant is funded by the UK Department for Business, Energy and Industrial Strategy and delivered by the British Council. The authors would like to thank the EPRIEOR unit and staff as the surface and interfacial tension and contact angle measurements and chemical flooding tests were conducted at the EPRI-EOR unit.Peer reviewedPublisher PD