Evaluation of sound pressure levels of infrassons and low frequency noise in Coentral Grande

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Infrassound and low frequency noise from wind farms – case study comparative study in relation to seasonal variation (winter and summer)

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Interaction systems design and the protocol- and middleware-centred paradigms in distributed application development

This paper aims at demonstrating the benefits and importance of interaction systems design in the development of distributed applications. We position interaction systems design with respect to two paradigms that have influenced the design of distributed applications: the middleware-centred and the protocol-centred paradigm. We argue that interaction systems that support application-level interactions should be explicitly designed, using the externally observable behaviour of the interaction system as a starting point in interaction systems design. This practice has two main benefits: to promote a systematic design method, in which the correctness of the design of an interaction system can be assessed against its service specification; and, to shield the design of application parts that use the interaction system from choices in the design of the supporting interaction system

On the Notion of Abstract Platform in MDA Development

Although platform-independence is a central property in MDA models, the study of platform-independence has been largely overlooked in MDA. As a consequence, there is a lack of guidelines to select abstraction criteria and modelling concepts for platform-independent design. In addition, there is little methodological support to distinguish between platform-independent and platform-specific concerns, which could be detrimental to the beneficial exploitation of the PIM-PSM separation-of-concerns adopted by MDA. This work is an attempt towards clarifying the notion of platform-independent modelling in MDA development. We argue that each level of platform-independence must be accompanied by the identification of an abstract platform. An abstract platform is determined by the platform characteristics that are relevant for applications at a certain level of platform-independence, and must be established by balancing various design goals. We present some methodological principles for abstract platform design, which forms a basis for defining requirements for design languages intended to support platform-independent design. Since our methodological framework is based on the notion of abstract platform, we pay particular attention to the definition of abstract platforms and the language requirements to specify abstract platforms. We discuss how the concept of abstract platform relates to UML

Analysis and design of sinusoidal quadrature RC-oscillators

Modern telecommunication equipment requires components that operate in many different frequency bands and support multiple communication standards, to cope with the growing demand for higher data rate. Also, a growing number of standards are adopting the use of spectrum efficient digital modulations, such as quadrature amplitude modulation (QAM) and orthogonal frequency division multiplexing (OFDM). These modulation schemes require accurate quadrature oscillators, which makes the quadrature oscillator a key block in modern radio frequency (RF) transceivers. The wide tuning range characteristics of inductorless quadrature oscillators make them natural candidates, despite their higher phase noise, in comparison with LC-oscillators. This thesis presents a detailed study of inductorless sinusoidal quadrature oscillators. Three quadrature oscillators are investigated: the active coupling RC-oscillator, the novel capacitive coupling RCoscillator, and the two-integrator oscillator. The thesis includes a detailed analysis of the Van der Pol oscillator (VDPO). This is used as a base model oscillator for the analysis of the coupled oscillators. Hence, the three oscillators are approximated by the VDPO. From the nonlinear Van der Pol equations, the oscillators’ key parameters are obtained. It is analysed first the case without component mismatches and then the case with mismatches. The research is focused on determining the impact of the components’ mismatches on the oscillator key parameters: frequency, amplitude-, and quadrature-errors. Furthermore, the minimization of the errors by adjusting the circuit parameters is addressed. A novel quadrature RC-oscillator using capacitive coupling is proposed. The advantages of using the capacitive coupling are that it is noiseless, requires a small area, and has low power dissipation. The equations of the oscillation amplitude, frequency, quadrature-error, and amplitude mismatch are derived. The theoretical results are confirmed by simulation and by measurement of two prototypes fabricated in 130 nm standard complementary metal-oxide-semiconductor (CMOS) technology. The measurements reveal that the power increase due to the coupling is marginal, leading to a figure-of-merit of -154.8 dBc/Hz. These results are consistent with the noiseless feature of this coupling and are comparable to those of the best state-of-the-art RC-oscillators, in the GHz range, but with the lowest power consumption (about 9 mW). The results for the three oscillators show that the amplitude- and the quadrature-errors are proportional to the component mismatches and inversely proportional to the coupling strength. Thus, increasing the coupling strength decreases both the amplitude- and quadrature-errors. With proper coupling strength, a quadrature error below 1° and amplitude imbalance below 1% are obtained. Furthermore, the simulations show that increasing the coupling strength reduces the phase noise. Hence, there is no trade-off between phase noise and quadrature error. In the twointegrator oscillator study, it was found that the quadrature error can be eliminated by adjusting the transconductances to compensate the capacitance mismatch. However, to obtain outputs in perfect quadrature one must allow some amplitude error

The role of the RM-ODP computational viewpoint concepts in the MDA approach

An MDA design approach should be able to accommodate designs at different levels of platform-independence. We have proposed a design approach previously (in [2]), which allows these levels to be identified. An important feature of this approach is the notion of abstract platform. An abstract platform is determined by the platform characteristics that are relevant for applications at a certain level of platform-independence, and must be established by considering various design goals. In this paper, we define a framework that makes it possible to use RM-ODP concepts in our MDA design approach. This framework allows a recursive application of the computational viewpoint at different levels of platform-independence. This is obtained by equating the RM-ODP notion of infrastructure to our notion of abstract platform

Abstract Interactions and Interaction Refinement in Model-Driven Design

In a model-driven design process the interaction between application parts can be described at various levels of platform-independence. At the lowest level of platform-independence, interaction is realized by interaction mechanisms provided by specific middleware platforms. At higher levels of platform-independence, interaction must be described in such a way that it can be further refined and realized onto a number of different middleware platforms, each with its particular interaction mechanisms and implementation constraints. In this paper, we investigate concepts that support interaction design at various levels of middleware-platform-independence. Also, we propose design operations for interaction refinement. The application of these operations to source designs results in target designs that take into account implementation constraints imposed by platforms, while preserving characteristics prescribed in source designs

Mergers & acquisitions research: A bibliometric study of top strategy and international business journals, 1980–2010

Mergers and acquisitions (M&As) are important modes through which firms carry out their domestic and international strategies and have been noted as the CEOs favorite strategy. As a significant field of study, M&Aresearch has accumulated substantial knowledge. This bibliometric study examines the extant strategy and international business literature on M&As. Methodologically, we examined a sample of 334 articles published in sixteen leading management/business journals, during a 31 year period — from 1980 to 2010. The results provide a global perspective of the field, identifying the works that have had the greater impact, the intellectual interconnections among authors and works, the main research traditions, or themes, delved upon on M&Arelated research. Structural and longitudinal analyses reveal the changes in the intellectual structure of the field over time. A discussion on the accumulated knowledge and future research avenues concludes this paper.info:eu-repo/semantics/publishedVersio

Recheio : growing through a declining channel : a case on wholesale food private labels and its competitiveness

The Portuguese wholesale food market is in a mature phase where the space to grow seems to be limited. In the end of 2008 economic and business environment were expected to deteriorate intensely making this growth even more difficult wholesale food companies. Recheio, the market leader in this sector, had been growing sustainably and regardless the situation they wanted to keep their pace. As so Mr. Antunes challenged the Marketing Director Rita Silva, to develop a strategy to boost the Traditional Retail channel sales since it was the one with the one decreasing the most. Due to its lack of capacity to compete with Modern Retail chains Mrs. Silva and her team worked to understand the gap between these two channels in order to build the necessary management tools to increase traditional retailers´ competitiveness and Recheio sales. These management tools could be as simple as more competitive prices or as complex as developing a Private Label but one thing was clear, waiting to see the exact evolution without any of these actions was not an option