Abstract

Abstract
This paper is on variable-speed wind turbines with permanent magnet generator. A three-mass drive train model and two different topologies for the power-electronic converters are considered. The two different topologies considered are respectively a matrix and a multilevel converter. A control strategy, based on fractional-order controllers, is proposed for the wind turbines. Previous papers were mainly focused on the transient stability of variable-speed wind turbines at external grid faults. Instead, this paper considers the possibility of an internal abnormal operating condition, namely a converter control malfunction. The influence of the converter control malfunction on the harmonic current emissions is studied. Comprehensive results are presented, and conclusions are duly drawn. © 2011 IEEE.

Abstract
Functional programs often combine separate parts using intermediate data structures for communicating results. Programs so defined are modular, easier to understand and maintain, but suffer from inefficiencies due to the generation of those gluing data structures. To eliminate such redundant data structures, some program transformation techniques have been proposed. One such technique is shortcut fusion, and has been studied in the context of both pure and monadic functional programs. In this paper, we study several shortcut fusion extensions, so that, alternatively, circular or higher-order programs are derived. These extensions are also provided for effect-free programs and monadic ones. Our work results in a set of generic calculation rules, that are widely applicable, and whose correctness is formally established. © 2011 Springer Science+Business Media, LLC.

Abstract
The evolution of tourism websites is converging to a set of features and best practices that are becoming standard, in such a way that developing a template and later customizing it to a given tourist region is becoming feasible. A very important feature in this kind of site is showing the touristic suggestions of what the tourist can find in the destination, optimally personalized for him/her. One problem in deploying such functionality however is the lack of user experience data suited to perform data mining when a new site is launched. This paper proposes a solution, customizable to any touristic region, that harnesses the information available in Flickr, crossing it with a Point of Interest (POI) database and using Google Prediction API (Application Programming Interface) to generate personalized travel suggestions, based on the geographical itinerary the user defined with a trip planner tool. © 2011 IEEE.

Abstract
A large-core air-clad photonic crystal fiber-based sensing structure is described, which is sensitive to refractive index. The sensing head is based on multimodal interference, and relies on a single-mode/large-core air-clad photonic crystal fiber (PCF)/single-mode fiber configuration. Using two distinct large-core air-clad PCF geometries-one for refractive index measurement and the other for temperature compensation, it was possible to implement a sensing head sensitive to refractive index changes in water as induced by temperature variations. The results indicated the high sensitivity of this sensing head to refractive index variations of water, and a resolution of 3: 4 x 10(-5) refractive index units could be achieved. (C) 2011 Optical Society of America

Abstract
This paper is on variable-speed wind turbines with permanent magnet synchronous generator (PMSG). A three-mass drive train model and two different topologies for the power-electronic converters are considered. The two topologies considered are a matrix and a multilevel converter. A fractional-order control strategy is proposed for the wind turbines. Computer simulation results are presented to illustrate the behavior of the wind turbines during a converter control malfunction. Finally, conclusions are duly drawn. © 2011 IEEE.