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Publications

2017

Deriving and improving CMA-ES with information geometric trust regions

Authors
Abdolmaleki, A; Price, B; Lau, N; Reis, LP; Neumann, G;

Publication
Proceedings of the Genetic and Evolutionary Computation Conference, GECCO 2017, Berlin, Germany, July 15-19, 2017

Abstract
CMA-ES is one of the most popular stochastic search algorithms. It performs favourably in many tasks without the need of extensive parameter tuning. The algorithm has many beneficial properties, including automatic step-size adaptation, efficient covariance updates that incorporates the current samples as well as the evolution path and its invariance properties. Its update rules are composed of well established heuristics where the theoretical foundations of some of these rules are also well understood. In this paper we will fully derive all CMA-ES update rules within the framework of expectation-maximisation-based stochastic search algorithms using information-geometric trust regions. We show that the use of the trust region results in similar updates to CMA-ES for the mean and the covariance matrix while it allows for the derivation of an improved update rule for the step-size. Our new algorithm, Trust-Region Co-variance Matrix Adaptation Evolution Strategy (TR-CMA-ES) is fully derived from first order optimization principles and performs favourably in compare to standard CMA-ES algorithm. © 2017 ACM.

2017

Digital Mammography DREAM Challenge: Participant Experience 2 (Conference Presentation)

Authors
Pereira, JC;

Publication
Medical Imaging 2017: Computer-Aided Diagnosis, Orlando, Florida, United States, 11-16 February 2017

Abstract

2017

Initial Solution Heuristic for Portfolio Optimization of Electricity Markets Participation

Authors
Faia, R; Pinto, T; Vale, ZA;

Publication
Highlights of Practical Applications of Cyber-Physical Multi-Agent Systems - International Workshops of PAAMS 2017, Porto, Portugal, June 21-23, 2017, Proceedings

Abstract

2017

heartBEATS: A hybrid energy approach for real-time B-spline explicit active tracking of surfaces

Authors
Barbosa, D; Pedrosa, J; Heyde, B; Dietenbeck, T; Friboulet, D; Bernard, O; D'hooge, J;

Publication
Computerized Medical Imaging and Graphics

Abstract
In this manuscript a novel method is presented for left ventricle (LV) tracking in three-dimensional ultrasound data using a hybrid approach combining segmentation and tracking-based clues. This is accomplished by coupling an affine motion model to an existing LV segmentation framework and introducing an energy term that penalizes the deviation to the affine motion estimated using a global Lucas–Kanade algorithm. The hybrid nature of the proposed solution can be seen as using the estimated affine motion to enhance the temporal coherence of the segmented surfaces, by enforcing the tracking of consistent patterns, while the underlying segmentation algorithm allows to locally refine the estimated global motion. The proposed method was tested on a dataset composed of 24 4D ultrasound sequences from both healthy volunteers and diseased patients. The proposed hybrid tracking platform offers a competitive solution for fast assessment of relevant LV volumetric indices, by combining the robustness of affine motion tracking with the low computational burden of the underlying segmentation algorithm. © 2017 Elsevier Ltd

2017

Detection of Behavioral Patterns for Increasing Attentiveness Level

Authors
Duraes, D; Goncalves, S; Carneiro, D; Bajo, J; Novais, P;

Publication
INTELLIGENT SYSTEMS DESIGN AND APPLICATIONS (ISDA 2016)

Abstract
In the current world, performance is one of the most important issues concerning work and competition. Performance is strongly connected with learning and when it comes to acquiring new knowledge, attention is one the most important mechanisms as the level of the learner's attention affects learning results. When students are doing learning activities using new technologies, it is extremely important that the teacher has some feedback from the students' work in order to detect potential learning problems at an early stage. The goal of this research is to propose a system that measures the level of attentiveness in real scenarios, and detects patterns of behavior associated to different attention levels among different students. This system measures attention and uses this information for training a decision support system that shows the level of attention of a group of students in real time.

2017

An Energy Credit Based Incentive Mechanism for the Direct Load Control of Residential HVAC Systems Incorporation in Day-Ahead Planning

Authors
Erdinc, O; Tascikaraoglu, A; Paterakis, NG; Catalao, JPS;

Publication
2017 IEEE MANCHESTER POWERTECH

Abstract
The increasing operational complexity of power systems considering the higher renewable energy penetration and changing load characteristics, together with the recent developments in the ICT field have led to more research and implementation efforts related to the activation of the demand side. In this manner, different direct load control (DLC) and indirect load control concepts have been developed and DLC strategies are considered as an effective tool for load serving entities (LSEs) with several real-world application examples. In this study, a new DLC strategy tailored for residential air-conditioners (ACs) participating in the day-ahead planning, based on offering energy credits to the enrolled end-users is proposed. The mentioned energy credits are then used by residential end-users to lower their energy procurement costs during peak-price periods. The strategy is formulated as a stochastic mixed-integer linear programming (MILP) model considering uncertainties related to weather conditions. The outcomes regarding the end-user comfort level and economic benefits are also analyzed.

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