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Publications

2017

Introduction to the special issue on architecture of computing systems

Authors
Hannig, F; Cardoso, JMP; Fey, D;

Publication
JOURNAL OF SYSTEMS ARCHITECTURE

Abstract

2017

FIRST ATTEMPT TOWARDS THE DEVELOPMENT OF TRANSTIBIAL PROSTHESIS

Authors
Alves, J; Ferreira, C; Reis, LP; Santos, CP; Seabra, E; Carvalho, H;

Publication
PROCEEDINGS OF THE 7TH INTERNATIONAL CONFERENCE ON MECHANICS AND MATERIALS IN DESIGN (M2D2017)

Abstract
This work addresses the field of the artificial devices that replace a missing body limb, particularly the prosthesis used upon a transtibial (TT) amputation, also known as ankle-foot prosthesis. A major challenge in designing an ankle-foot prosthesis lies in synthesizing a mechanism that will functionally mimic the missing part of an anatomical leg and, therefore, restoring the normal gait of the amputee. This way, it will be discussed and presented the requirements for a TT prosthesis, the steps that lead to the primary sketches of the prosthetic model and its main mechanism. This work constitutes a preliminary research in the field of the bionic TT prosthesis.

2017

AN ECONOMIC ENERGY APPROACH FOR QUERIES ON DATA CENTERS

Authors
Saraiva, J; Guimarales, M; Belot, O;

Publication
PROCEEDINGS OF THE 3RD INTERNATIONAL CONFERENCE ON ENERGY AND ENVIRONMENT (ICEE 2017)

Abstract
Energy consumption is an issue that involves all of us, both as individuals and as members of a society, and covers all our areas of activity. It is something so broad that its impact has important reflections on our social, cultural and financial structures. The domain of software, and in particular database systems, is not an exception. Although it seems to be a little bit strange to study the energy consumption of just one query, when we consider the execution of a a few thousand queries per second, quickly we see the importance of the querying consumption in the monthly account of any company that has a conventional data center. To demonstrate the energy consumption of queries in data centers, we idealized a small dashboard for monitoring and analyzing the sales of a company, and implemented all the queries needed for populating it and ensuring its operation. The queries were organized into two groups, oriented especially to two distinct database management systems: one relational (MySQL) and one non relational (Neo4J). The goal is to evaluate the energy consumption of different types of queries, and at the same time compare it in terms of relational and non-relational database approaches. This paper relates the process we implemented to set up the energy consumption application scenario, measure the energy consumption of each query, and present our first preliminary results.

2017

Energy Efficiency across Programming Languages

Authors
Pereira, R; Couto, M; Ribeiro, F; Rua, R; Cunha, J; Fernandes, JP; Saraiva, J;

Publication
SLE'17: PROCEEDINGS OF THE 10TH ACM SIGPLAN INTERNATIONAL CONFERENCE ON SOFTWARE LANGUAGE ENGINEERING

Abstract
This paper presents a study of the runtime, memory usage and energy consumption of twenty seven well-known software languages. We monitor the performance of such languages using ten different programming problems, expressed in each of the languages. Our results show interesting findings, such as, slower/faster languages consuming less/more energy, and how memory usage influences energy consumption. We show how to use our results to provide software engineers support to decide which language to use when energy efficiency is a concern.

2017

Exact Methods for Recursive Circle Packing

Authors
Gleixner, AmbrosM.; Maher, Stephen; Müller, Benjamin; Pedroso, JoaoPedro;

Publication
CoRR

Abstract

2017

Renegotiation of Electronic Brokerage Contracts

Authors
Cunha, R; Veloso, B; Malheiro, B;

Publication
RECENT ADVANCES IN INFORMATION SYSTEMS AND TECHNOLOGIES, VOL 2

Abstract
CloudAnchor is a multiagent e-commerce platform which offers brokerage and resource trading services to Infrastructure as a Service (IaaS) providers and consumers. The access to these services requires the prior negotiation of Service Level Agreements (SLA) between the parties. In particular, the brokerage SLA (bSLA), which is mandatory for a business to have access to the platform, specifies the brokerage fee the business will pay every time it successfully trades a resource within the platform. However, while the negotiation of the resource SLA (rSLA) includes the uptime of the service, the brokerage SLA was negotiated for an unspecified time span. Since the commercial relationship defined through the bSLA - between a business and the platform can be long lasting, it is essential for businesses to be able to renegotiate the bSLA terms, i.e., renegotiate the brokerage fee. To address this issue, we designed a bSLA renegotiation mechanism, which takes into account the duration of the bSLA as well as the past behaviour (trust) and success (transactions) of the business in the CloudAnchor platform. The results show that the implemented bSLA renegotiation mechanism privileges, first, the most reliable businesses, and, then, those with higher volume of transactions, ensuring that the most reliable businesses get the best brokerage fees and resource prices. The proposed renegotiation mechanism promotes the fulfilment of SLA by all parties and increases the satisfaction of the trustworthy businesses in the CloudAnchor platform.

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