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Publications

2017

The Impact of Ageing and the Speed of Ageing on the Economic Growth of Least Developed, Emerging and Developed Countries, 1990-2013

Authors
Teixeira, AAC; Renuga Nagarajan, NR; Silva, ST;

Publication
REVIEW OF DEVELOPMENT ECONOMICS

Abstract
Studies relating ageing and countries' economic performance address mostly developed economies. However, extant studies demonstrate that less developed countries (LDC) and emerging economies (EE) are reaching the transition process faster than those from developed regions, which renders the speed of ageing, besides ageing, a critical variable to explore in this context. Comparing system dynamic panel data estimations for 40 LDC, 19 EE and 28 developed countries (DC), between 1990 and 2013, we uncovered that ageing is detrimental to countries' economic growth, with noticeable nuances depending on countries' development level. The current level of ageing significantly and negatively impacts on DC's growth but not on that of LDC or EE. For these latter groups, the most relevant issue is the speed of ageing. The current annual growth of old age dependency ratio significantly diminishes EE's growth prospects whereas the lagged annual growth of the ageing index and the old age dependency ratio significantly curtails LDC's growth. Such results emphasize the need for urgent public policies that might mitigate the imbalance in LDCs' age structure before the speed of ageing leads LDCs to become even much poorer.

2017

Systematic Spreadsheet Construction Processes

Authors
Mendes, J; Cunha, J; Duarte, F; Engels, G; Saraiva, J; Sauer, S;

Publication
2017 IEEE SYMPOSIUM ON VISUAL LANGUAGES AND HUMAN-CENTRIC COMPUTING (VL/HCC)

Abstract
Spreadsheets are used in professional business contexts to make decisions based on collected data. Usually, these spreadsheets are developed by end users in an ad-hoc way. Thus, the business logic of a concrete spreadsheet is not explicit to end users, making its correctness hard to assess and users have to trust. We present an approach where structure and computational behavior of a spreadsheet are specified by a model with a process-like notation based on pre-defined functional spreadsheet services with typed interfaces. This enables a consistent construction process of a spreadsheet that comprises defining its structure and computational behavior as well as filling it with data and executing the defined computational behavior. Thus, concrete spreadsheets are equipped with a specification of their construction process. This supports their understanding and correct usage, even in case of legacy spreadsheets. The approach has been developed in cooperation with an industrial partner.

2017

Residential MPC Controller Performance in a Household with PV Microgeneration

Authors
Silva, JMF; Godina, R; Rodrigues, EMG; Pouresmaeil, E; Catalao, JPS;

Publication
2017 IEEE MANCHESTER POWERTECH

Abstract
The energy demand of the residential sector and the adjacent option for fossil fuels has negative consequences by both greenhouse gases (GHG), CO2 and other air pollutants emissions. The home energy demand consists mainly of energy requirements for space and water heating along with the energy dedicated for appliances. Therefore, different strategies that aim to stimulate an efficient use of energy need to be reinforced at all levels of human activity. In this paper a comparison is made between a Model Predictive Control (MPC) model, the ON/OFF and proportional-integral-derivative (PID) control models of an air conditioning unit AC system controlling the temperature of a room. The model of the house with local Photovoltaic (PV) solar microgeneration is assumed to be located in a Portuguese city. The household of the case study is subject to the local solar irradiance, temperature and electricity tariff of a summer day.

2017

Optimum Design of Small-Scale Stand-Alone Hybrid Renewable Energy Systems

Authors
Lujano Rojas, JM; Dufo López, R; Bernal Agustín, JL; Osório, GJ; Catalão, JPS;

Publication
Optimization in Renewable Energy Systems: Recent Perspectives

Abstract
A crucial factor for the sustainable development of human society is access to electricity. This fact has motivated the development of renewable energy systems isolated or connected to the electric distribution network. Evaluation of autonomous hybrid energy systems from a technical and economic perspective is a difficult problem that requires using complex mathematical models of renewable sources and generators, such as photovoltaic (PV) panels and wind turbines, and the implementation of optimization techniques in order to obtain an economically successful design. This chapter describes and analyzes traditional isolated energy systems powered by solar PV and wind energies provided with a battery energy storage system. Simulation and optimization are illustrated through the analysis of a rural electrification project in Tangiers (Morocco) in order to provide electricity to rural clinic. Optimization analysis suggests the installation of a PV/BESS system due to the magnitude of the load to be supplied, operating costs, and environmental conditions.

2017

Fabry-Perot Sensor based on Two Coupled Microspheres for Strain Measurement

Authors
Monteiro, CS; Kobelke, J; Schuster, K; Bierlich, J; Frazao, O;

Publication
2017 25TH INTERNATIONAL CONFERENCE ON OPTICAL FIBER SENSORS (OFS)

Abstract
A Fabry-Perot based sensor with two coupled hollow microspheres is presented. The sensor was fabricated using fusion splicing techniques, enabling a low-cost, highly reproducible, production. The coupling of the two microspheres gives rise to a highly sensitive strain sensor, reaching a sensitivity of 4.07 pm/mu epsilon. The allsilica composition leads to a low thermal sensitivity, making the proposed structure suitable applications in environments with varying external conditions.

2017

Patterns of technology acquisition: Upstream linkages between MNEs and local suppliers

Authors
Moreira, AC;

Publication
Foreign Direct Investments (FDIs) and Opportunities for Developing Economies in the World Market

Abstract
Although MNEs are important players in the present global world, there has been a debate regarding, on one hand, how MNEs contribute to the development of indigenous firms in host countries, and on the other hand, how indigenous suppliers are able to cope with their international technology demanding clients. This chapter analyzes the patterns of technology acquisition of 40 firms that supply eight multinational firms that belong to four different industries. It is possible to conclude that there are certain differences among foreign and indigenous suppliers as well across the industries they belong to. These differences are the result of a cumulative process over time, which reflect the different performances of the companies and their relationships with the environment.

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