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Publicações

2012

CORRUPTION AND MULTINATIONAL COMPANIES' ENTRY MODES - DO LINGUISTIC AND HISTORICAL TIES MATTER?

Autores
Grande, M; Teixeira, AAC;

Publicação
SOUTH AFRICAN JOURNAL OF ECONOMIC AND MANAGEMENT SCIENCES

Abstract
The literature on FDI entry modes and corruption tends to convey the idea that corruption leads to a choice between low equity modes, i.e. joint ventures with local partners, and non-equity modes, namely exports and contracting, in order to avoid contact with corrupt state officials. Recently, some studies have argued that despite corruption, linguistic and historical ties between home and host countries lead MNCs to prefer high-equity modes. Focusing on a rather unexplored setting, the African countries, most specifically the Portuguese-speaking ones (PALOP - Paises Africanos de LIngua Oficial Portuguesa), which include countries where levels of corruption are very high (e.g., Guinea-Bissau and Angola), high (e. g., Mozambique, Sao Tome and Principe), and intermediate (e.g., Cape Verde), maintaining also close linguistic and historical ties with Portugal, we found that the FDI entry mode is associated with the less corrupt markets. Thus, our results do not support the recent contention that cultural and historical links are likely to perform a mediating role, by fostering foreign direct investment, in supporting African countries to overcome the dismal growth some have been facing in the last few decades. On the contrary, our findings highlight the pressing need for these countries to combat corruption if higher economic growth via FDI attraction is envisioned.

2012

Automatic Lane Detection in Chromatography Images

Autores
Moreira, BM; Sousa, AV; Mendonca, AM; Campilho, A;

Publicação
IMAGE ANALYSIS AND RECOGNITION, PT II

Abstract
This paper proposes a method for automating the detection of lanes in Thin-Layer Chromatography images. Our approach includes a preprocessing step to detect the image region of interest, followed by background estimation and removal. This image is then projected onto the horizontal direction to integrate the information into a one-dimensional profile. A smoothing filter is applied to this profile and the outcome is the input of the lane detection process, which is performed in three phases. The first one aims at obtaining an initial set of candidate lanes that are further validated or removed in the second phase. The last phase is a refinement step that allows the inclusion of lanes that are not clearly distinguishable in the profile and that were not included in the initial set. The method was evaluated in 66 chromatography images and achieved values of recall, precision and F-beta-measure of 97.0%, 99.4% and 98.2%, respectively.

2012

Dispatching heuristics for the single machine weighted quadratic tardiness scheduling problem

Autores
Valente, JMS; Schaller, JE;

Publicação
COMPUTERS & OPERATIONS RESEARCH

Abstract
In this paper, we consider the single machine scheduling problem with weighted quadratic tardiness costs. Several efficient dispatching rules are proposed. These include existing heuristics for the linear problem, as well as procedures suitably adapted to the quadratic objective function. Also, both forward and backward scheduling procedures are considered. The computational results show that the heuristics that specifically take into account the quadratic objective significantly outperform their linear counterparts. Also, the backward scheduling approach proves to be superior, and the difference in performance is even more noticeable for the harder instances. The best of the backward scheduling heuristics is both quite efficient and effective. Indeed, this procedure can quickly generate a schedule even for large instances. Also, its relative deviation from the optimum is usually rather low, and it performs adequately even for the more difficult instances.

2012

Beat Tracking for Multiple Applications: A Multi-Agent System Architecture With State Recovery

Autores
Oliveira, JL; Davies, MEP; Gouyon, F; Reis, LP;

Publicação
IEEE TRANSACTIONS ON AUDIO SPEECH AND LANGUAGE PROCESSING

Abstract
In this paper we propose an audio beat tracking system, IBT, for multiple applications. The proposed system integrates an automatic monitoring and state recovery mechanism, that applies (re-)inductions of tempo and beats, on a multi-agent-based beat tracking architecture. This system sequentially processes a continuous onset detection function while propagating parallel hypotheses of tempo and beats. Beats can be predicted in a causal or in a non-causal usage mode, which makes the system suitable for diverse applications. We evaluate the performance of the system in both modes on two application scenarios: standard (using a relatively large database of audio clips) and streaming (using long audio streams made up of concatenated clips). We show experimental evidence of the usefulness of the automatic monitoring and state recovery mechanism in the streaming scenario (i.e., improvements in beat tracking accuracy and reaction time). We also show that the system performs efficiently and at a level comparable to state-of-the-art algorithms in the standard scenario. IBT is multi-platform, open-source and freely available, and it includes plugins for different popular audio analysis, synthesis and visualization platforms.

2012

Enriching temporal query understanding through date identification: How to tag implicit temporal queries?

Autores
Campos, R; Dias, G; Jorge, AM; Nunes, C;

Publicação
ACM International Conference Proceeding Series

Abstract
Generically, search engines fail to understand the user's temporal intents when expressed as implicit temporal queries. This causes the retrieval of less relevant information and prevents users from being aware of the possible temporal dimension of the query results. In this paper, we aim to develop a language-independent model that tackles the temporal dimensions of a query and identifies its most relevant time periods. For this purpose, we propose a temporal similarity measure capable of associating a relevant date(s) to a given query and filtering out irrelevant ones. Our approach is based on the exploitation of temporal information from web content, particularly within the set of k-top retrieved web snippets returned in response to a query. We particularly focus on extracting years, which are a kind of temporal information that often appears in this type of collection. We evaluate our methodology using a set of real-world text temporal queries, which are clear concepts (i.e. queries which are non-ambiguous in concept and temporal in their purpose). Experiments show that when compared to baseline methods, determining the most relevant dates relating to any given implicit temporal query can be improved with a new temporal similarity measure. © 2012 ACM.

2012

Addressing the impact of demand and generation cost uncertainties in the operation of power systems

Autores
Gomes, BA; Saraiva, JT;

Publicação
IET Conference Publications

Abstract
This paper describes a set of mathematical formulations designed to include uncertainties modeled by fuzzy numbers in DC OPF studies. These approaches enhance and generalize an initial formulation and solution algorithm described in several papers co-authored by the second author. The approaches described in this paper adopt multiparametric optimization techniques in order to translate to the results the uncertainties affecting loads, for one side, the generation costs, for another, and also both of them in a simultaneous way. These approaches can be very useful nowadays given the uncertainties and volatility affecting data required to run several studies. They can also be the basis for the computation of nodal short time marginal prices reflecting these uncertainties. This paper also includes results obtained from a Case Study based on the IEEE 24 bus test system.

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