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Publications

2020

Analysis of Brand Resonance Measures to Access, Dimensionality, Reliability and Validity

Authors
Raut, UR; Brito, PQ; Pawar, PA;

Publication
GLOBAL BUSINESS REVIEW

Abstract
The aim of the present study is to analyze brand resonance measures to assess reliability, dimensionality and validity using existing models of brand resonance. This study is based on a mixed approach of research methodology, using qualitative and quantitative methods. In the qualitative approach, we use expert interview and focus group discussion tools. In the quantitative approach, a corporate survey was conducted and 560 responses were collected through a structured questionnaire. The analysis is performed using statistical scaling tools such as Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA). This study initiated scale extraction and operationalization processes for 72 observed variables to measure nine latent variables and obtained 34 statistically extracted observed variables. The study provides a reliable and validated means to measure brand resonance constructs. The study develops a brand resonance scale, which can help brand managers to measure consumers' levels of brand resonance, in order to describe the strength of the bond of their consumer with their brand(s). This study develops empirically extracted measures of brand resonance, making it distinctive in the branding literature. The study also ensures all important aspects of measurement scale, such as validity and reliability.

2020

Monopolistic and Game-Based Approaches to Transact Energy Flexibility

Authors
Shokri Gazafroudi, AS; Shafie Khah, M; Prieto Castrillo, F; Manuel Corchado, JM; Catalao, JPS;

Publication
IEEE TRANSACTIONS ON POWER SYSTEMS

Abstract
The appearance of the flexible behavior of end-users based on demand response programs makes the power distribution grids more active. Thus, electricity market participants in the bottom layer of the power system, wish to be involved in the decision-making process related to local energy management problems, increasing the efficiency of the energy trade in distribution networks. This paper proposes monopolistic and game-based approaches for the management of energy flexibility through end-users, aggregators, and the Distribution System Operator (DSO) which are defined as agents in the power distribution system. Besides, a 33-bus distribution network is considered to evaluate the performance of our proposed approaches for energy flexibility management model based on impact of flexibility behaviors of end-users and aggregators in the distribution network. According to the simulation results, it is concluded that although the monopolistic approach could be profitable for all agents in the distribution network, the game-based approach is not profitable for end-users.

2020

Photoplethysmography based atrial fibrillation detection: a review

Authors
Pereira, T; Tran, N; Gadhoumi, K; Pelter, MM; Do, DH; Lee, RJ; Colorado, R; Meisel, K; Hu, X;

Publication
NPJ DIGITAL MEDICINE

Abstract
AbstractAtrial fibrillation (AF) is a cardiac rhythm disorder associated with increased morbidity and mortality. It is the leading risk factor for cardioembolic stroke and its early detection is crucial in both primary and secondary stroke prevention. Continuous monitoring of cardiac rhythm is today possible thanks to consumer-grade wearable devices, enabling transformative diagnostic and patient management tools. Such monitoring is possible using low-cost easy-to-implement optical sensors that today equip the majority of wearables. These sensors record blood volume variations—a technology known as photoplethysmography (PPG)—from which the heart rate and other physiological parameters can be extracted to inform about user activity, fitness, sleep, and health. Recently, new wearable devices were introduced as being capable of AF detection, evidenced by large prospective trials in some cases. Such devices would allow for early screening of AF and initiation of therapy to prevent stroke. This review is a summary of a body of work on AF detection using PPG. A thorough account of the signal processing, machine learning, and deep learning approaches used in these studies is presented, followed by a discussion of their limitations and challenges towards clinical applications.

2020

Decentralised demand response market model based on reinforcement learning

Authors
Shafie Khah, M; Talari, S; Wang, F; Catalao, JPS;

Publication
IET SMART GRID

Abstract
A new decentralised demand response (DR) model relying on bi-directional communications is developed in this study. In this model, each user is considered as an agent that submits its bids according to the consumption urgency and a set of parameters defined by a reinforcement learning algorithm called Q-learning. The bids are sent to a local DR market, which is responsible for communicating all bids to the wholesale market and the system operator (SO), reporting to the customers after determining the local DR market clearing price. From local markets' viewpoint, the goal is to maximise social welfare. Four DR levels are considered to evaluate the effect of different DR portions in the cost of the electricity purchase. The outcomes are compared with the ones achieved from a centralised approach (aggregation-based model) as well as an uncontrolled method. Numerical studies prove that the proposed decentralised model remarkably drops the electricity cost compare to the uncontrolled method, being nearly as optimal as a centralised approach.

2020

Using Artificial Intelligence to Predict Academic Performance

Authors
Reis, A; Rocha, T; Martins, P; Barroso, J;

Publication
HCI (42)

Abstract
The academic performance of a higher education student can be affected by several factors and in most cases Higher Education Institutions (HEI) have programs to intervene, prevent failure or students dropping out. These include student tutoring, mentoring, recovery classes, summer school, etc. Being able to identify the borderline cases is extremely important for planning and intervening in time. This position paper reports on an ongoing project, being developed at the University of Trás-os-Montes e Alto Douro (UTAD), which uses the students’ data and artificial intelligence algorithms to create models and predict the performance of students and classes. The main objective of the IA.EDU project is to research the usage of data, artificial intelligence and data science to create artificial intelligence solutions, including models and applications, to provide predictive information that can contribute to the increase in students’ academic success and a reduction in the dropout rate, by making it possible to act proactively with the students at risk, course directors and course designers.

2020

Pyramid wavefront sensor optical gains compensation using a convolutional model

Authors
Chambouleyron, V; Fauvarque, O; Janin Potiron, P; Correia, C; Sauvage, JF; Schwartz, N; Neichel, B; Fusco, T;

Publication
ASTRONOMY & ASTROPHYSICS

Abstract
Context. Extremely large telescopes are overwhelmingly equipped with pyramid wavefront sensors (PyWFS) over the more widely used Shack-Hartmann wavefront sensor to perform their single-conjugate adaptive optics (SCAO) mode. The PyWFS, a sensor based on Fourier filtering, has proven to be highly successful in many astronomy applications. However, this sensor exhibits non-linear behaviours that lead to a reduction of the sensitivity of the instrument when working with non-zero residual wavefronts. This so-called optical gains (OG) effect, degrades the closed-loop performance of SCAO systems and prevents accurate correction of non-common path aberrations (NCPA). Aims. In this paper, we aim to compute the OG using a fast and agile strategy to control PyWFS measurements in adaptive optics closed-loop systems. Methods. Using a novel theoretical description of PyWFS, which is based on a convolutional model, we are able to analytically predict the behaviour of the PyWFS in closed-loop operation. This model enables us to explore the impact of residual wavefront errors on particular aspects such as sensitivity and associated OG. The proposed method relies on the knowledge of the residual wavefront statistics and enables automatic estimation of the current OG. End-to-end numerical simulations are used to validate our predictions and test the relevance of our approach. Results. We demonstrate, using on non-invasive strategy, that our method provides an accurate estimation of the OG. The model itself only requires adaptive optics telemetry data to derive statistical information on atmospheric turbulence. Furthermore, we show that by only using an estimation of the current Fried parameter r0 and the basic system-level characteristics, OGs can be estimated with an accuracy of less than 10%. Finally, we highlight the importance of OG estimation in the case of NCPA compensation. The proposed method is applied to the PyWFS. However, it remains valid for any wavefront sensor based on Fourier filtering subject from OG variations.

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