2,206 research outputs found
Wireless Power Transfer and Data Collection in Wireless Sensor Networks
In a rechargeable wireless sensor network, the data packets are generated by
sensor nodes at a specific data rate, and transmitted to a base station.
Moreover, the base station transfers power to the nodes by using Wireless Power
Transfer (WPT) to extend their battery life. However, inadequately scheduling
WPT and data collection causes some of the nodes to drain their battery and
have their data buffer overflow, while the other nodes waste their harvested
energy, which is more than they need to transmit their packets. In this paper,
we investigate a novel optimal scheduling strategy, called EHMDP, aiming to
minimize data packet loss from a network of sensor nodes in terms of the nodes'
energy consumption and data queue state information. The scheduling problem is
first formulated by a centralized MDP model, assuming that the complete states
of each node are well known by the base station. This presents the upper bound
of the data that can be collected in a rechargeable wireless sensor network.
Next, we relax the assumption of the availability of full state information so
that the data transmission and WPT can be semi-decentralized. The simulation
results show that, in terms of network throughput and packet loss rate, the
proposed algorithm significantly improves the network performance.Comment: 30 pages, 8 figures, accepted to IEEE Transactions on Vehicular
Technolog
Continuous-time Mean-Variance Portfolio Selection with Stochastic Parameters
This paper studies a continuous-time market {under stochastic environment}
where an agent, having specified an investment horizon and a target terminal
mean return, seeks to minimize the variance of the return with multiple stocks
and a bond. In the considered model firstly proposed by [3], the mean returns
of individual assets are explicitly affected by underlying Gaussian economic
factors. Using past and present information of the asset prices, a
partial-information stochastic optimal control problem with random coefficients
is formulated. Here, the partial information is due to the fact that the
economic factors can not be directly observed. Via dynamic programming theory,
the optimal portfolio strategy can be constructed by solving a deterministic
forward Riccati-type ordinary differential equation and two linear
deterministic backward ordinary differential equations
Synthesis and structures of O-anthrylmethyl-substituted hexahomotrioxacalix[3]arenes
O-Alkylation of 7,15,23-tri-tert-butyl-25,26,27-trihydroxy-2,3,10,11,18,19-hexahomo-3,11,19-trioxacalix[3]arene (1Hâ) with 9-chloromethylanthracene 5 was carried out under different reaction conditions. Variation of the number of anthrylmethyl group introduced at the phenolic rim of hexahomotrioxacalix[3]arene 1Hâ was achieved through selective O-alkylation using stoichiometric amounts of 9-chloromethylanthracene 5 in acetone to afford the mono-O-alkylated product 2HâAn, the di-O-alkylated product 3HAnâ and the tri-O-alkylated product partial-cone-4Anâ, respectively. Interestingly, by using an acetone/benzene (1:1 v/v) mixed solvent system, the cone-4Anâ was successfully synthesized. These results suggest that the solvent can also control the conformation of the O-alkylation products. The possible reaction routes of the cone-4Anâ and partial-cone-4Anâ are also discussed
Workplace flexibility and organisational citizenship behaviour: An investigation of the mediating role of engagement and moderating role of perceived fairness
This study aims to better understand the effect of employee engagement and perceived fairness on positive workplace behaviour. Using the social exchange theory (SET) and agent-system model, this study investigated: 1) the mediating role of employee engagement in linking workplace flexibility with organisational citizenship behaviour (OCB); 2) the moderating role of perceived fairness in influencing the mediation. The conceptual model and defined hypotheses were measured using hierarchical multiple regression, different mediation approaches, and Edwards and Lambert's (2007) moderated mediation analysis. Aiken and West's (1991) simple slope test was used to illustrate the moderation effect of perceived fairness. The findings suggest that workplace flexibility was significantly related to OCB with employee engagement serving as a partial mediator. Perceived fairness moderated the mediating relationship but a stronger effect was found for low perceived fairness than for high perceived fairness. Findings from this study imply the necessity of creating flexibility in the workplace for positive employee behaviour
SWAG: Item Recommendations using Convolutions on Weighted Graphs
Recent advancements in deep neural networks for graph-structured data have
led to state-of-the-art performance on recommender system benchmarks. In this
work, we present a Graph Convolutional Network (GCN) algorithm SWAG (Sample
Weight and AGgregate), which combines efficient random walks and graph
convolutions on weighted graphs to generate embeddings for nodes (items) that
incorporate both graph structure as well as node feature information such as
item-descriptions and item-images. The three important SWAG operations that
enable us to efficiently generate node embeddings based on graph structures are
(a) Sampling of graph to homogeneous structure, (b) Weighting the sampling,
walks and convolution operations, and (c) using AGgregation functions for
generating convolutions. The work is an adaptation of graphSAGE over weighted
graphs. We deploy SWAG at Target and train it on a graph of more than 500K
products sold online with over 50M edges. Offline and online evaluations reveal
the benefit of using a graph-based approach and the benefits of weighing to
produce high quality embeddings and product recommendations.Comment: 10 pages, 8 figures, 2019 IEEE BigData special sessio
220204
In this paper, we demonstrate a new ultra-wideband (UWB) localization testbed, which tracks a UWB tag and estimates locations of obstacles based on channel impulse response measurements. Anchor nodes that are developed with off-the-shelf Decawave DW1000 UWB transceivers are deployed to cover the area of interest. The testbed is implemented and preliminary experiments are carried out to estimate the location of the object by analyzing channel impulse response strength of the UWB tag.This work was partially supported by National Funds through
FCT/MCTES (Portuguese Foundation for Science and Technology),
within the CISTER Research Unit (UIDP/UIDB/04234/2020); also by
the Operational Competitiveness Programme and Internationalization (COMPETE 2020) under the PT2020 Partnership Agreementinfo:eu-repo/semantics/publishedVersio
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