5,479 research outputs found

    Secrecy performance of TAS/SC-based multi-hop harvest-to-transmit cognitive WSNs under joint constraint of interference and hardware imperfection

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    In this paper, we evaluate the secrecy performance of multi-hop cognitive wireless sensor networks (WSNs). In the secondary network, a source transmits its data to a destination via the multi-hop relaying model using the transmit antenna selection (TAS)/selection combining (SC) technique at each hop, in the presence of an eavesdropper who wants to receive the data illegally. The secondary transmitters, including the source and intermediate relays, have to harvest energy from radio-frequency signals of a power beacon for transmitting the source data. Moreover, their transmit power must be adjusted to satisfy the quality of service (QoS) of the primary network. Under the joint impact of hardware imperfection and interference constraint, expressions for the transmit power for the secondary transmitters are derived. We also derive exact and asymptotic expressions of secrecy outage probability (SOP) and probability of non-zero secrecy capacity (PNSC) for the proposed protocol over Rayleigh fading channel. The derivations are then verified by Monte Carlo simulations.Web of Science195art. no. 116

    Well-Rounded ideal lattices of cyclic cubic and quartic fields

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    In this paper, we find criteria for when cyclic cubic and cyclic quartic fields have well-rounded ideal lattices. We show that every cyclic cubic field has at least one well-rounded ideal. We also prove that there exist families of cyclic quartic fields which have well-rounded ideals and explicitly construct their minimal bases. In addition, for a given prime number pp, if a cyclic quartic field has a unique prime ideal above pp, then we provide the necessary and sufficient conditions for that ideal to be well-rounded. Moreover, in cyclic quartic fields, we provide the prime decomposition of all odd prime numbers and construct an explicit integral basis for every prime ideal.Comment: 26 page

    Well-Rounded Twists of Ideal Lattices from Imaginary Quadratic Fields

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    In this paper, we investigate the properties of well-rounded twists of a given ideal lattice of an imaginary quadratic field KK. We show that every ideal lattice II of KK has at least one well-rounded twist lattice. Moreover, we provide an explicit algorithm to compute all well-rounded twists of II.Comment: 24 page

    Variational Geometric Approach To Generalized Differential And Conjugate Calculi In Convex Analysis

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    This paper develops a geometric approach of variational analysis for the case of convex objects considered in locally convex topological spaces and also in Banach space settings. Besides deriving in this way new results of convex calculus, we present an overview of some known achievements with their unified and simplified proofs based on the developed geometric variational schemes. Key words. Convex and variational analysis, Fenchel conjugates, normals and subgradients, coderivatives, convex calculus, optimal value functions

    Cumulative Quality Modeling for HTTP Adaptive Streaming

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    Thanks to the abundance of Web platforms and broadband connections, HTTP Adaptive Streaming has become the de facto choice for multimedia delivery nowadays. However, the visual quality of adaptive video streaming may fluctuate strongly during a session due to bandwidth fluctuations. So, it is important to evaluate the quality of a streaming session over time. In this paper, we propose a model to estimate the cumulative quality for HTTP Adaptive Streaming. In the model, a sliding window of video segments is employed as the basic building block. Through statistical analysis using a subjective dataset, we identify three important components of the cumulative quality model, namely the minimum window quality, the last window quality, and the average window quality. Experiment results show that the proposed model achieves high prediction performance and outperforms related quality models. In addition, another advantage of the proposed model is its simplicity and effectiveness for deployment in real-time estimation. The source code of the proposed model has been made available to the public at https://github.com/TranHuyen1191/CQM

    Tournament-Based Incentives and Mergers and Acquisitions

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    This research examines the relation between tournament-based incentives, which are proxied by the difference between a firm’s CEO pay and the median pay of the senior managers, and mergers and acquisitions (M&As). We find that tournament-based incentives are positively related to firm acquisitiveness and acquiring firms’ stock and operating performance. Further analysis indicates that positive acquisition performance increases the likelihood of the CEO being promoted from inside the acquiring firm. Our evidence is consistent with the view that tournament-based incentives motivate acquiring firms’ managers to make greater efforts and take more risk that result in superior acquisition performance

    ZSM-5/SBA-15 versus Al-SBA-15 as supports for the hydrocracking/hydroisomerization of alkanes

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    [EN] Al-SBA-15 and ZSM-5/SBA-15 (ZSC) composite were synthesized following hydrothermal procedures in the presence of triblock copolymer Poly(ethylene glycol)- poly(propylene glycol)-poly(ethylene glycol) (Pluronic P123) and a mixture of tetrapropylammonium bromide (TPABr)/Pluronic P123 templates, respectively. Pt (0.5 wt.%)/Al-SBA-15 and ZSC bifunctional catalysts were then prepared by a wet impregnation methodology and investigated in the hydrocracking/hydroisomerization of n-decane. Pt/ZSC, containing a trimodal porous texture and high Bronsted acidity, exhibited hydrocracking activity while Pt/Al-SBA-15, showing merely Lewis acidity, was active for hydroisomerization. At 300 degrees C the conversion of n-decane on Pt/ZSC reached 98% and cracking selectivity was about 99%. Both catalysts were exhaustively characterized.This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 104.05-2014.21. CM aknowledges financial support by the Spanish Government-MINECO through "Severo Ochoa" (SEV 2012-0267) and CTQ2015-70126-R.Huyen, PT.; Nam, LTH.; Vinh, TQ.; Martínez, C.; Parvulescu, VI. (2018). ZSM-5/SBA-15 versus Al-SBA-15 as supports for the hydrocracking/hydroisomerization of alkanes. Catalysis Today. 306:121-127. https://doi.org/10.1016/j.cattod.2017.03.040S12112730
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