Search results for "Networks"

Energy efficient optimisation for large-scale multiple-antenna system with WPT

2018

In this study, an energy-efficient optimisation scheme for a large-scale multiple-antenna system with wireless power transfer (WPT) is presented. In the considered system, the user is charged by a base station with a large number of antennas via downlink WPT and then utilises the received power to carry out uplink data transmission. Novel antenna selection, time allocation and power allocation schemes are presented to optimise the energy efficiency of the overall system. In addition, the authors also consider channel state information cannot be perfectly obtained when designing the resource allocation schemes. The non-linear fractional programming-based algorithm is utilised to address the …

influence of raw data analysis for the use of neural networks for wind farm productivity prediction

2011

In the last decade wind energy had a strong growth because of cost effectiveness of the technology and the high remunerative of investments. The increase of wind power penetration in power grids, however, makes necessary the development of instruments for prediction of productivity of a wind farm. This paper presents a study dealing with the capability of neural network to forecast short term production of a wind farm by the correlation of wind and energy production data. Available measures of wind parameters were related to productivity data of a real wind farm. Also wind data not strictly related to the site have been used in order to assess their possible influence on the production. Aft…

Customers' perceived risk and trust in using mobile money services-an empirical study of Ghana

2019

Copyright © 2019, IGI Global. Although mobile money (MM) has been explored in the existing literature, the roles of trust and risk in MM use have received little attention from researchers. Furthermore, many of the existing studies have treated these constructs as unidimensional. The extant literature also shows that perceived risk has received little attention from researchers who have conducted studies on MM. Thus, the objective of this study is to examine the roles of trust and perceived risk in customers' intent to adopt MM services in Ghana. Both trust and perceived risk were broken down into various dimensions. The study involved 671 respondents who were selected via an intercept appr…

Memory degradation induced by attention in recurrent neural architectures

2022

This paper studies the memory mechanisms in recurrent neural architectures when attention models are included. Pure-attention models like Transformers are more and more popular as they tend to outperform models with recurrent connections in many different tasks. Our conjecture is that attention prevents the recurrent connections from transferring information properly between consecutive next steps. This conjecture is empirically tested using five different models, namely, a model without attention, a standard Loung attention model, a standard Bahdanau attention model, and our proposal to add attention to the inputs in order to fill the gap between recurrent and parallel architectures (for b…

Sell in good company : social capital as a strategic tool in the fine art auction business

2013

Anomaly Detection and Classification of Household Electricity Data : A Time Window and Multilayer Hierarchical Network Approach

2022

With the increasing popularity of the smart grid, huge volumes of data are gathered from numerous sensors. How to classify, store, and analyze massive datasets to facilitate the development of the smart grid has recently attracted much attention. In particular, with the popularity of household smart meters and electricity monitoring sensors, a large amount of data can be obtained to analyze household electricity usage so as to better diagnose the leakage and theft behaviors, identify man-made tampering and data fraud, and detect powerline loss. In this paper, the time window method is first proposed to obtain the features and potential periodicity of household electricity data. Combining th…

Community-based method for extracting backbones

2022

Networks are an adequate representation for modeling and analyzing a great variety of complex systems. However, understanding networks with millions of nodes and billions of connections can be pretty challenging due to memory and time constraints. Therefore, selecting the relevant nodes and edges of these large-scale networks while preserving their core information is a major issue. In most cases, the so-called backbone extraction methods are based either on coarse-graining or filtering approaches. Coarse-graining techniques reduce the network size by gathering similar nodes into super-nodes, while filter-based methods eliminate nodes or edges according to a statistical property. In this wo…

Dynamic MAC Parameters Configuration for Performance Optimization in 802.11e Networks

2006

Quality of service support in wireless LAN is a theme of current interest. Several solutions have been proposed in literature in order to protect time-sensitive traffic from best-effort traffic. According to the EDCA proposal, which is a completely distributed solution, the service differentiation is provided by giving probabilistically higher number of channel accesses to stations involved in real-time applications. To this purpose, the MAC parameter settings of each contending stations can be tuned dynamically. In this paper, we face the problem of tuning the EDCA MAC parameters in common scenarios in which a given number of low-rate delay-sensitive traffic flows share the channel with so…

Remarks on IEEE 802.11 DCF Performance Evaluation, IEEE Communication Letters, Vol. 9, Issue 8, Aug 2005 pp:765 - 767

2005

This letter presents a new approach to evaluate the throughput/delay performance of the 802.11 Distributed Coordination Function (DCF). Our approach relies on elementary conditional probability arguments rather than bidimensional Markov chains (as proposed in previous models), and can be easily extended to account for backoff operation more general than DCF's one

On the accuracy of some common modeling assumptions for EDCA analysis

2005

Several models have been discussed in literature in order to evaluate the performance of the EDCA differentiation mechanisms. Despite of the exponential back off rules, usually the EDCA protocol has been modeled as a persistent slotted access protocol, and summarized into a set of access probabilities. These models often show a very different complexity and accuracy, according to the basis assumptions. In this paper, we propose a new modeling approach for EDCA, in which the medium access is described in terms of backoff counter comparisons, contention by contention, and no restrictive hypothesis is considered. Through our model, we verify the applicability of the most common protocol simpli…