Eventos

Prova de Tópicos de Investigação

8 Fevereiro 2018, 18:36 - Maria de Lurdes Piado Farrusco

Candidate: José Miguel Santos Ribeiro Nº 90937/D

Title:  Data Mining in passive Wi-Fi data - An application to BeanStalk dataset

Date: 09/02/2018

Time: 11h00

Location: Sala 6.11, Torre Norte, Alameda

Advisor: Professor Nuno Jardim Nunes 

Abstract: Tourism is one of the world’s largest industries fundamentally arising from mobility as a form of capital. This ever-growing economy has the potential to be analyzed in the way that the visitors use the infrastructures available and the locations at their disposal. This paper presents the exploration of BeanStalk - a low-cost Wi-Fi based platform deployed in Madeira islands, that makes it possible to track people - with the known techniques of frequent itemsets, sequential patterns, and association rule mining, to sense and visualize not only which groups of attractions are more visited, but also to derive probabilities of visiting an attraction knowing the ones already visited before, and what implications it has in urban planning and event scheduling. The results present the data analysis, statistics and derived rules for the different seasons of the year, highlighting how they differ over time, and between the devices that are classified in the dataset as locals and visitors.


Prova de Tópicos de Investigação

22 Janeiro 2018, 18:00 - Fátima Sampaio


Candidate: Renata Alves Castelo Branco N.º 72757/D

Title: Algorithmic Architectural Visualization

Date: 31/01/2018

Time: 16h00

Location: Sala 0.20, Pavilhão de Informática II, IST, Alameda

Advisor: Professor António Paulo Teles de Menezes Correia Leitão

Abstract: Digitally-generated visualizations, such as renders or movies, are, nowadays, commonly used as representation methods for architectural creations. This occurs not only in final stages of the process, with the goal of selling the product’s image, but also in midst creation process to express concepts and ideas. Presently, the spread of parametric and algorithmic approaches to design creates a problem for visualization, as it enables the almost effortless change of 3D models, thus requiring repeated visualization efforts to keep up with the changes applied to the design. To solve this, we propose extending the algorithmic design approach to also include the high-level description of architectural image creation. The methodology, Algorithmic Architectural Visualization (AAV), also contemplates the required preparation settings for the visualization process, and includes possible visualization productions inspired by film techniques.


Prova de Tópicos de Investigação

19 Janeiro 2018, 17:57 - Fátima Sampaio


Candidate: Pedro Luís Galvão Raminhas N.º 70627/D

Title: Enhancing efficiency of Hybrid Transactional Memory via Dynamic Data Partitioning Schemes

Date: 23/01/2018

Time: 16h00

Location: Sala 0.20, Pavilhão de Informática II, IST, Alameda

Advisor: Professor Paolo Romano 

Abstract: Transactional Memory (TM) is an emerging paradigm that promises to significantly ease the development of parallel programs. Hybrid TM (HyTM) is probably the most promising implementation of the TM abstraction, which seeks to combine the high efficiency of hardware implementations (HTM) with the robustness and flexibility of software-based ones (STM). Unfortunately, though, existing Hybrid TM systems are known to suffer from high overheads to guarantee correct synchronization between concurrent transactions executing in hardware and software.This article introduces DMP-TM (Dynamic Memory Partitioning-TM), a novel HyTM algorithm that exploits, to the best of our knowledge for the first time in the literature, the idea of leveraging operating system-level memory protection mechanisms to detect conflict between HTM and STM transactions. This innovative design allows for employing highly scalable ORec-based STM implementations, while avoiding any instrumentation on the HTM path.This allows DMP-TM to achieve up to ∼ 20× speedups compared to state of the art Hybrid TM solutions in uncontended workloads. Further, thanks to the use of simple and lightweight self-tuning mechanisms, DMP-TM achieves robust performance even in unfavourable workload that exhibit high contention between the STM and HTM path."


Prova de Tópicos de Investigação

19 Janeiro 2018, 11:23 - Fátima Sampaio


Candidate: Bruno Filipe Belo Ferreira N.º 69919/D

Title: Context-Oriented Algorithmic Design

Date: 22/01/2018

Time: 11h00

Location: Sala 0.19, Pavilhão de Informática II, IST, Alameda 

Advisor: Professor António Paulo Teles de Menezes Correia Leitão

Abstract: Currently, algorithmic approaches are being introduced in several areas of expertise, namely Architecture. Algorithmic Design (AD) is an approach for architecture that allows architects to take advantage of algorithms to produce complex forms for their projects, to simplify the exploration of variations, or to mechanize tasks, including those related to analysis and optimization of designs. However, architects might need different models of the same project for different kinds of analysis, which tempts them to extend the same code base for different purposes, typically making the code brittle and hard to understand. In this paper, we propose the extend AD with Context-Oriented Programming (COP), a programming paradigm based on context that dynamically changes the behavior of the code. To this end, we propose a COP library and we explore its combination with an AD tool. Finally, we re-implement a case study with our approach, and discuss the advantages and disadvantages.


Talk by Prof.ª Joana Pais_ISEG

4 Janeiro 2018, 12:44 - Maria Lucília Gonçalves Abreu

Title: Static versus Dynamic Deferred Acceptance in School Choice: Theory and Experiment

Speaker: Prof.ª Joana Pais_ISEG

Date: January 11th 2018

Time: 15:00

Location: Sala Polivalente do DEI, porta 0.17, Pavilhão de Informática II, Campus_Alameda

Abstract

In the context of school choice, we experimentally study how behavior and outcomes are affected when, instead of submitting rankings in the student proposing or receiving deferred acceptance (DA) mechanism, participants make decisions dynamically, going through the steps of the underlying algorithms. Our main results show that, contrary to theory, (a) in the dynamic student proposing DA mechanism, participants propose to schools respecting the order of their true preferences slightly more often than in its static version while, (b) in the dynamic student receiving DA mechanism, participants react to proposals by always respecting the order and not accepting schools in the tail of their true preferences more often than in the corresponding static version. As a consequence, for most problems we test, no significant differences exist between the two versions of the student proposing DA mechanisms in what stability and average payoffs are concerned, but the dynamic version of the student receiving DA mechanism delivers a clear improvement over its static counterpart in both dimensions. In fact, in the aggregate, the dynamic school proposing DA mechanism is the best performing mechanism.

Bio

Joana Pais is an Associate Professor at the Department of Economics of ISEG, a coordinator of the Master in Economics, and of the Ph.D in Economics. Her research interests include matching theory, market design, and experimental economics. Ph.D in Economics, University Autònoma de Barcelona.