416,774 research outputs found

    An adaptive neuro-fuzzy propagation model for LoRaWAN

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    This article proposes an adaptive-network-based fuzzy inference system (ANFIS) model for accurate estimation of signal propagation using LoRaWAN. By using ANFIS, the basic knowledge of propagation is embedded into the proposed model. This reduces the training complexity of artificial neural network (ANN)-based models. Therefore, the size of the training dataset is reduced by 70% compared to an ANN model. The proposed model consists of an efficient clustering method to identify the optimum number of the fuzzy nodes to avoid overfitting, and a hybrid training algorithm to train and optimize the ANFIS parameters. Finally, the proposed model is benchmarked with extensive practical data, where superior accuracy is achieved compared to deterministic models, and better generalization is attained compared to ANN models. The proposed model outperforms the nondeterministic models in terms of accuracy, has the flexibility to account for new modeling parameters, is easier to use as it does not require a model for propagation environment, is resistant to data collection inaccuracies and uncertain environmental information, has excellent generalization capability, and features a knowledge-based implementation that alleviates the training process. This work will facilitate network planning and propagation prediction in complex scenarios

    Conquering the Virtual Public': Jean-Paul Sartre's La tribune des temps modernes and the Radio in France

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    On the evening of Monday, 21 October 1947, La Tribune de Paris – a daily radio programme that provided a forum for discussion and analysis of current events – gave over its nightly news review, from 8:30 to 8:50, to ‘Jean-Paul Sartre et ses collaborateurs’. This new programme, scheduled to run weekly on Monday evenings, was La tribune des temps modernes. Sartre’s ‘collaborateurs’ were a rotating group of fellow editors of his journal, Les temps modernes, for which the radio programme was named. They included Simone de Beauvoir and Maurice Merleau-Ponty as regulars, alongside important contributions from Jean Pouillon, Jean-Bertrand Pontalis and Alain Bonafé. Structured as a semiscripted discussion, La tribune des temps modernes ran in the regular weekly slot for six weeks, before being abruptly cancelled in December, following a controversial run and – probably crucially – a change of government

    What is Sound?

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    (Abstract to follow

    Overview of ISM bands and Software-defined Radio Experimentation

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    Wireless systems using low-power wireless communication protocol are rapidly gain popularity in the license-free industrial scientific, and medical (ISM) frequency bands. One such emerging trend in ISM frequency bands is home automation. Historically, all the home devices were once unconnected, today are now being connected either by a wired or wireless connection. The low-power wireless communication protocols enable integration of all the digital home devices into a single system and enhance end user product experience. The rapid prototyping of these end user product using programmable radio system such as software-defined radio (SDR) has been the game-changer in the field of home automation. In this article, we present an overview of popular ISM bands in different regions of the world. Furthermore, we analyze the signals from the wireless electric switch using a software-defined radio in 433 MHz ISM band

    The coexistence of cognitive radio and radio astronomy

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    An increase of the efficiency of spectrum usage requires the development of new communication techniques. Cognitive radio may be one of those new technique, which uses unoccupied frequency bands for communications. This will lead to more power in the bands and therefore an increasing level of Radio Frequency Interference (RFI), which would cause loss of operation particularly for passive users of the spectrum, such as radio astronomy. This paper will address this issue and will present calculations indicating that the impact of cognitive radio on radio astronomy observations is considerable. The signal levels resulting from cognitive radio systems indicate that spectral bands used for cognitive radio applications cannot be used for radio astronomical research

    EC-CENTRIC: An Energy- and Context-Centric Perspective on IoT Systems and Protocol Design

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    The radio transceiver of an IoT device is often where most of the energy is consumed. For this reason, most research so far has focused on low power circuit and energy efficient physical layer designs, with the goal of reducing the average energy per information bit required for communication. While these efforts are valuable per se, their actual effectiveness can be partially neutralized by ill-designed network, processing and resource management solutions, which can become a primary factor of performance degradation, in terms of throughput, responsiveness and energy efficiency. The objective of this paper is to describe an energy-centric and context-aware optimization framework that accounts for the energy impact of the fundamental functionalities of an IoT system and that proceeds along three main technical thrusts: 1) balancing signal-dependent processing techniques (compression and feature extraction) and communication tasks; 2) jointly designing channel access and routing protocols to maximize the network lifetime; 3) providing self-adaptability to different operating conditions through the adoption of suitable learning architectures and of flexible/reconfigurable algorithms and protocols. After discussing this framework, we present some preliminary results that validate the effectiveness of our proposed line of action, and show how the use of adaptive signal processing and channel access techniques allows an IoT network to dynamically tune lifetime for signal distortion, according to the requirements dictated by the application

    The Passion to Fly and to the Courage to Lead: The Saga of Amelia Earhart – Leading Women into Flight

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    Truly a 20th Century leader, Amelia Earhart’s success was not only in breaking aviation records, but overcoming barriers for women. She set an example of courage, achievement, and not being afraid of envy, criticism, ignorance and indifference. Author Iodice explores this iconic figure in depth as a profound example of determination, commitment, and courage at a time where all societal expectations pointed to defeat and resignation
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