2012
Autores
Figueiredo, A; Figueiredo, F; Monteiro, NP; Straume, OR;
Publicação
Structural Change and Economic Dynamics
Abstract
We analyse the dynamics and evolution of the corporate restructuring process in the Portuguese banking sector, where 10 banks were privatised during the period 1989-1996. We apply a novel methodological approach in this context, using a multidimensional measure of restructuring that links product and labour market variables. We find evidence of considerable heterogeneity in the restructuring process, where firms adjust at different speeds and intensities. We also find that the wage level is by far the firm attribute that changed more, which is shown to reflect substantial changes in terms of composition, and not size, of the workforce. Our empirical evidence also suggests that privatisation is associated with a higher level of rent sharing. © 2011 Elsevier B.V.
2012
Autores
Cunha, J; Fernandes, JP; Saraiva, J;
Publicação
Proceedings of the ACM Symposium on Applied Computing
Abstract
Spreadsheets are among the most popular programming languages in the world. Unfortunately, spreadsheet systems were not tailored from scratch with modern programming language features that guarantee, as much as possible, program correctness. As a consequence, spreadsheets are populated with unacceptable amounts of errors. In other programming language settings, model-based approaches have been proposed to increase productivity and program effectiveness. Within spreadsheets, this approach has also been followed, namely by ClassSheets. In this paper, we propose an extension to ClassSheets to allow the specification of spreadsheets that can be viewed as relational databases. Moreover, we present a transformation from ClassSheet models to UML class diagrams enriched with OCL constraints. This brings to the spreadsheet realm the entire paraphernalia of model validation techniques that are available for UML. © 2012 ACM.
2012
Autores
Leite da Silva, AML; Nascimento, LC; da Rosa, MA; Issicaba, D; Pecas Lopes, JAP;
Publicação
IEEE TRANSACTIONS ON SMART GRID
Abstract
Wind and solar power are well known intermittent power sources with high availability uncertainties. Hence, whenever they are integrated to distribution systems, these power sources can increase significantly the complexity of system operation. This paper presents an impact analysis of distributed energy resources integration on distribution systems, focusing mainly on reliability aspects. Therefore, an interesting algorithm to correctly determine the amount of capacity that may be transferred to other feeders is presented and discussed, taken into consideration the presence of distributed generation. The methodology is tested in a typical Brazilian distribution system, assuming the integration of a diesel-based combined heat and power unit, wind turbines, and solar panels. The results provide general insights regarding the benefits of applying distributed generation to alleviate load transfer restrictions.
2012
Autores
Marcal, ARS; Mendonca, T; Silva, CSP; Pereira, MA; Rozeira, J;
Publicação
COMPUTATIONAL MODELLING OF OBJECTS REPRESENTED IN IMAGES: FUNDAMENTALS, METHODS AND APPLICATIONS III
Abstract
There is a considerable interest in the development of automatic image analysis systems for dermoscopic images. The standard approach usually consists of three stages: (i) image segmentation, (ii) feature extraction and selection, and (iii) lesion classification. This paper evaluates the potential of an alternative approach, based on the Menzies method. It consists on the identification of the presence of 1 or more of 6 possible color classes, indicating that the lesion should be considered a potential melanoma. The Jeffries-Matusita (JM) and Transformed Divergence (TD) separability measures were used for an experimental evaluation with 28 dermoscopic images. In the most challenging case tested, with training identified in multiple images, 8 out of 15 class pairs were found to be well separable, or 13+ 2 out of 21 considering the skin as an additional class.
2012
Autores
Coutinho, JGF; Carvalho, T; Durand, S; Cardoso, JMP; Nobre, R; Diniz, PC; Luk, W;
Publicação
AOSD'12 Companion - Proceedings of the 11th Annual International Conference on Aspect Oriented Software Development
Abstract
This demonstration presents a novel design-flow and aspect-oriented language called LARA [1], which is currently used to guide the mapping of high-level C application codes to heterogeneous high-performance embedded systems. In particular, LARA is capable of capturing complex strategies and schemes involving: hardware/software partitioning, code specialization, source code transformations and code instrumentation. A key element of LARA, and a distinguishing feature from existing approaches, is its ability to support the specification of non-functional requirements and user knowledge in a non-invasive way in the exploration of suitable implementations. The design-flow incorporates several tools, such as a LARA frontend, a hardware/software partitioning tool, an aspect weaver, cost estimator, and a source-level transformation engine. All these components can be coordinated as part of an elaborate application mapping strategy using LARA. In this demonstration, we illustrate how non-functional cross-cutting concerns such as runtime monitorization and performance are codified and described in LARA and how the weaving process affects selected applications. Furthermore, we also explain how third-party tools, such as gprof, can be incorporated into the design-flow and aspect description, for instance, to affect the hardware/software partitioning process. We demonstrate how LARA can be used to extract run-time information, such as range values of variables, and can control code transformations and compiler optimizations addressing customized implementations of the corresponding computations on FPGAs. © 2012 ACM.
2012
Autores
Issicaba, D; Pecas Lopes, JAP; da Rosa, MA;
Publicação
IEEE TRANSACTIONS ON POWER SYSTEMS
Abstract
This paper presents an adequacy and security evaluation of electric power distribution systems with distributed generation. For this accomplishment, bulk power system adequacy and security evaluation concepts are adapted to distribution system applications. The evaluation is supported by a combined discrete-continuous simulation model which emulates the distribution system operation. This model generates a sequence of operation states which are evaluated from a steady-state perspective using AC power flow computations. Frequency and voltage stability are also assessed using dynamic simulation in order to verify the feasibility of islanded operation. Simulation results are presented for the RBTS-BUS2-F1 as well as an actual feeder from the South of Brazil. The results emphasize the need to consider adequacy and security aspects in the distribution system assessments, mainly due to the ongoing integration of distributed energy resources.
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