Adaptive Signal Processing Strategy for a Wind Farm System Fault Accommodation

In order to improve the availability of offshore wind farms, thus avoiding unplanned operation and maintenance costs, which can be high for offshore installations, the accommodation of faults in their earlier occurrence is fundamental. This paper addresses the design of an active fault tolerant control scheme that is applied to a wind park benchmark of nine wind turbines, based on their nonlinear models, as well as the wind and interactions between the wind turbines in the wind farm. Note that, due to the structure of the system and its control strategy, it can be considered as a fault tolerant cooperative control problem of an autonomous plant. The controller accommodation scheme provides the on-line estimate of the fault signals generated by nonlinear filters exploiting the nonlinear geometric approach to obtain estimates decoupled from both model uncertainty and the interactions among the turbines. This paper proposes also a data-driven approach to provide these disturbance terms in analytical forms, which are subsequently used for designing the nonlinear filters for fault estimation. This feature of the work, followed by the simpler solution relying on a data-driven approach, can represent the key point when on-line implementations are considered for a viable application of the proposed scheme

Technological Revolutions and Economic Growth:The �Age of Steam� Reconsidered

revolution, economic growth, steam, technological

Technical Change and Economic Growth: Some Lessons from Secular Patterns and Some Conjectures on the Current Impact of ICT Technology

This paper discusses the link between patterns of technological change and economic development taking an evolutionary perspective. We argue that the modes and timing of such coupled dynamics are deeply influenced by the emergence of new techno-economic paradigms or regimes. ICT-based technologies are the drivers of the current paradigm, which, we show, is still at an early stage of diffusion, particularly for developing countries. Building from historical evidence, we argue that catching up of developing countries critically depends on their ability to master the technology behind the dominant technoeconomic paradigm. We then discuss threats and opportunities related to a possible ICTbased development path.Technical change, Economic Growth, ICT

Income Levels and Income Growth. Some New Cross-Country Evidence and Some Interpretative Puzzles

This work brings together two distinct ensembles of evidence concerning, at macro level, international distributions of incomes and their dynamics, and, at micro level, the size distributions of firms and the properties of their growth rates. Together, we also consider an intermediate level of observation, namely the properties of sectoral growth. First, our empirical analysis provides a fresh look at the international distri-butions of incomes and growth rates by investigating more closely the relationship between the two entities and the statistical properties of the growth process. Second, we try to identify those statistical properties which are invariant with respect to the scale of observation (country, sector or firm) as distinct from those that are instead scale specific. This exercise puts forward a few major interpretative challenges regarding the correlating processes underlying the statistical evidence.International Distribution of Incomes, International Growth Rates, Scaling Laws, Growth Volatility, Exponential Tails

The patterns of output growth of firms and countries: new evidence on scale invariances and scale specificities

This work brings together two distinct pieces of evidence concerning, at the macro level, international distributions of incomes and their dynamics, and, at the micro level, the size distributions of firms and the properties of their growth rates. First, our empirical analysis provides a new look at the international distribu- tions of incomes and growth rates by investigating more closely the relationship between the two entities and the statistical properties of the growth process. Second, we identify the statistical properties that are invariant with respect to the scale of observation (country or firm) as distinct from those that are scale specific. This exercise proposes a few major interpretative challenges regarding the correlating processes underlying the statistical evidence.International distribution of income, international growth rates, firm growth, scaling laws, growth volatility, exponential tails

The Grip of History and the Scope for Novelty: Some Results and Open Questions on Path Dependence in Economic Processes

-Path dependence, irreversibility, increasing returns, learning, lock-in.

Short-Pulsed Wavepacket Propagation in Ray-Chaotic Enclosures

Wave propagation in ray-chaotic scenarios, characterized by exponential sensitivity to ray-launching conditions, is a topic of significant interest, with deep phenomenological implications and important applications, ranging from optical components and devices to time-reversal focusing/sensing schemes. Against a background of available results that are largely focused on the time-harmonic regime, we deal here with short-pulsed wavepacket propagation in a ray-chaotic enclosure. For this regime, we propose a rigorous analytical framework based on a short-pulsed random-plane-wave statistical representation, and check its predictions against the results from finite-difference-time-domain numerical simulations.Comment: 11 pages, 11 figures; minor modifications in the tex