Abstract
This paper addresses the problem of providing frequency control services, including inertia emulation and primary frequency control, from offshore wind farms connected through a multiterminal HVDC network. The proposed strategy consists of a cascading control mechanism based on dc voltage regulation at the onshore converters and frequency regulation at the offshore converters. The control scheme involves only local measurements and actions avoiding security and reliability issues of control structures based on remote information. The effectiveness of the proposed strategy is illustrated in a test system that consists of two nonsynchronous areas linked by a multiterminal HVDC grid where two offshore wind farms are also connected.

Abstract

Abstract
Bidirectional Texture Functions (BTF) allow high quality visualization of real world materials exhibiting complex appearance and details that can not be faithfully represented using simpler analytical or parametric representations. Accurate representations of such materials require huge amounts of data, hindering real time rendering. BTFs compress the raw original data, constituting a compromise between visual quality and rendering time. This paper presents an implementation of a state of the art BTF representation on the GPU, allowing interactive high fidelity visualization of complex geometric models textured with multiple BTFs. Scalability with respect to the geometric complexity, amount of lights and number of BTFs is also studied.

Abstract

Abstract

Abstract
The use of Mobile Technologies opens new possibilities for the teaching and learning processes, taking us to a new reality, called Mobile Learning or m-Learning. The m-learning in this work is defined" as learning processes that occur, necessarily supported by the use of mobile technologies and that has mobility as a fundamental characteristic of human actors, who may be physically / geographically distant from other actors and also the physical spaces of formal education, such as classrooms, training rooms or the workplace" [1], [6]. It is author's intention to alert the academic community of the features in using M-Learning. We feel the need to develop of applications that use this type of technology, ensuring that education be accessible to all. The present work conducts a research of mobile learning as a tool to support education in higher Institutions. At same time, the authors of the present work investigated existing solutions, which have been using advanced mobile technologies to support learning process with emphasis in the use of mobile devices and they analyzed practical implications of design and education when they come into mobile virtual learning environments. A education software was developed to support the students in learning. To evaluate the system, we used the framework QEF (Quality Evaluation Framework) and we done a questionnaire. © 2012 IEEE.