1,720,964 research outputs found
Energy-Efficient Power Control for Multiple-Relay Cooperative Networks Using Q-Learning
Full text linkIn this paper, we investigate the power control problem in a cooperative network with multiple wireless transmitters, multiple amplify-and-forward relays, and one destination. The relay communication can be either full duplex or half-duplex, and all source nodes interfere with each other at every intermediate relay node, and all active nodes (transmitters and relay nodes) interfere with each other at the base station. A game-theory-based power control algorithm is devised to allocate the powers among all active nodes. The source nodes aim at maximizing their energy efficiency (in bits per Joule per Hertz), whereas the relays aim at maximizing the network sum rate. We show that the proposed game admits multiple pure/mixed-strategy Nash equilibrium points. A Q-learning-based algorithm is then formulated to let the active players converge to the best Nash equilibrium point that combines good performance in terms of both energy efficiency and overall data rate. Numerical results show that the full-duplex scheme outperforms half-duplex configuration, Nash bargaining solution, the max-min fairness, and the max-rate optimization schemes in terms of energy efficiency, and outperforms the half-duplex mode, Nash bargaining system, and the max-min fairness scheme in terms of network sum rate
Energy-efficient power control for drone communications
No full textThis work aims at developing an energy-efficient power control algorithm for a swarm of drones that simultaneously transmit data to the serving base station while moving around a given coverage area. A stochastic mobility model based on random walk is developed, which guarantees boundedness and continuity of the movement, and used in a non-cooperative stochastic differential game, with utility functions defined by an Hamilton-Jacobi-Bellman (HJB) equation for each drone. We analyze the existence and uniqueness of the equilibrium point, and develop a distributed algorithm whose convergence to such equilibrium point is guaranteed. Numerical results are used to validate the performance of the proposed solution
A Q-learning game-theory-based algorithm to improve the energy efficiency of a multiple relay-aided network
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Joint Spectrum and Computing Resource Allocation in Fog-Assisted Drone Communications for Ambiental Services
No full textFog computing allows for energy-efficient and low-latency offloading of computationally intensive tasks from wireless devices to nearby servers. The integration of this technology in drone communications enables the managing of challenging tasks such as the ones found in remote areas with complex civil protection environments, such as disaster areas and emergency zones. In this paper, we propose a joint resource allocation scheme that optimizes both radio and computational resources for fog-assisted drone communication networks. Each drone decides whether to execute its task locally on its edge node or offload it to a fog node deployed on the base station (BS). Our scalable solution effectively minimizes service latency and energy consumption jointly, while taking into account physical- and application-layer constraints. Specifically, we allocate the CPU frequency capacity of both the local edge node and the remote fog node, as well as link bandwidth. Wireless channels to access the BS are limited, so only the most beneficial drones offload their tasks, while others use their local edge nodes. We formulate the power dissipation of various electronic circuits in the network using practical models. To develop the bi-objective minimization for each drone, we apply the Tchebysheff theorem, which derives the Pareto boundary between the two objectives (service latency and energy consumption). The competition among drones is modeled using the non-cooperative game framework, and the existence and uniqueness of the Nash equilibrium (NE) are proven. NE is computed using an algorithm based on subgradient projection. Numerical results concerning both theoretical aspects and a practical case study are presented to corroborate the efficiency of the proposed solution
Co-PARAFAC: A Novel Cost-Efficient Scalable Tensor Decomposition Algorithm
No full textThis paper proposes a novel tensor decomposition method, cooperative parallel factor (Co-PARAFAC), that is devised to achieve higher accuracy with lower computational complexity and memory requirements than the conventional PARAFAC. The rationale relies on dividing a given tensor, even with a large size, into smaller disjoint sub-tensors, which are independently and parallelly decomposed using the conventional PARAFAC. The intermediate results are then properly merged to obtain the decomposition of the original tensor. As case study, we apply Co-PARAFAC to estimate the uplink channels of RIS-assisted wireless communications. Simulation results corroborate the efficiency of the Co-PARAFAC in achieving significantly lower computational complexity and higher channel estimation accuracy than the conventional PARAFAC. Broadly, the proposed algorithm is advantageous in various fields requiring efficient and high accurate tensor decomposition
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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