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In this paper a hybrid passivity based and fuzzy type-2 controller for chaotic and hyper-chaotic systems is presented. The proposed control strategy is an appropriate choice to be implemented for the stabilization of chaotic and hyper-chaotic systems due to the energy considerations of the passivity based controller and the flexibility and capability of the fuzzy type-2 controller to deal with uncertainties. As it is known, chaotic systems are those kinds of systems in which one of their Lyapunov exponents is real positive, and hyper-chaotic systems are those kinds of systems in which more than one Lyapunov exponents are real positive. In this article one chaotic Lorentz attractor and one four dimensions hyper-chaotic system are considered to be stabilized with the proposed control strategy. It is proved that both systems are stabilized by the passivity based and fuzzy type-2 controller, in which a control law is designed according to the energy considerations selecting an appropriate storage function to meet the passivity conditions. The fuzzy type-2 controller part is designed in order to behave as a state feedback controller, exploiting the flexibility and the capability to deal with uncertainties. This work begins with the stability analysis of the chaotic Lorentz attractor and a four dimensions hyper-chaotic system. The rest of the paper deals with the design of the proposed control strategy for both systems in order to design an appropriate controller that meets the design requirements. Finally, numerical simulations are done to corroborate the obtained theoretical results.

Management of Renewable Static Synchronous Generation units based on Synchronous Power Controller (RSSG-SPC), not only provides grid synchronization without using PLL and gives proper dynamic to output active power, moreover yields simple solution to overcome technical constraints on these units. Control of active power level injected to the grid is one of these key constraints which can overcome by an Active Power Limiter (APL). In this work, an APL designed based on the classic power equation is proposed for this kind of modern RSSG-SPCs. Primary Simulink analysis and real time test results confirm that suggested APL can control and limit both maximum and minimum level of output active power for several grid connection cases.

Time synchronization is an important factor to take into account when performing collaborative and distributed tasks along a sensor network. Message exchange based time synchronization algorithms ported to underwater acoustic sensor networks, have to deal with high latency communications, besides frame Doppler scaling and frame detection at the receiver side, which are key points for an accurate synchronization. Furthermore, mobile sensor networks lead to different propagation times in a bidirectional message exchange, such as the ones used to synchronize two sensors. In addition to time synchronization algorithm, a first order kinematic model in conjunction with Doppler estimation can be applied to precise frame time stamping and avoid drift between clocks. In this paper we present a complete time synchronization scheme optimized for mobile network, tested in simulation and experimented in real tests demonstrating high performance in time synchronization accuracy. Award-winning

Vector current control based on Phase-locked loop, regardless of its popularity in control of grid-connected converters, performs under the limitation of the short-circuit capacity of the connected ac system. A previously proposed method, power-synchronization control (PSC), by L. Zhang et al. has been demonstrated good performance in HVDC links especially in case of weak ac grid interconnection. This method utilizes the internal synchronization mechanism, analogous to the operation of a synchronous machine in ac grids. By using this technique, the voltage source converter (VSC) avoids the instability caused by a standard PLL in a weak ac-system connection. Moreover, a VSC terminal can give the weak ac system strong voltage support, just like a common synchronous machine does. In this paper, generalized voltage droop (GVD) strategy is developed based on PSC to provide more flexibility in control paradigm of MTDC grids and smoother transition among different operation modes of converter stations. GVD is implemented at the primary layer of a two-layer hierarchical control structure of MTDC grid, and brings about some new features such as fixed power control and fixed dc voltage control, additional to the conventional voltage droop characteristics. The mode transition can be achieved according to the set point given by the secondary layer of the control framework. Analytical justifications are given to demonstrate the effectiveness in each control mode and the capability in soft mode transition.

This paper proposes a new auxiliary Subsynchronous Damping Controller (SSDC) for the Static Var Compensator (SVC) to damp out subsynchronous oscillations in power system containing series compensated transmission lines. The arrival of Wide Area Measurement (WAM) technology has made it possible to measure the states of a large power system interconnected with synchronized Phasor Measurement Units (PMU). This paper presents the idea of using remote signals obtained from PMU to damp SSR. An auxiliary subsynchronous damping controller (SSDC) has been proposed for a SVC, using the generator rotor speed deviation signal as the stabilizing signal to damp subsynchronous oscillations. Sturdiness of the controller has been examined by applying the disturbances in the system that causes significant changes in generator's operating point. The IEEE Second Benchmark (SBM) model is used for the analysis and the SVC is simulated using the Power System Block set (PSB) in the MATLAB/Simulink environment.

The increasing penetration of renewable energy sources in power systems requires new control systems that provide services similar to those of conventional generators. This paper proposes an active power controller that is able to automatically achieve synchronization with the grid and to control the DC link voltage. Through this controller, the converter can be identified with a virtual synchronous generator whose kinetic energy is stored in the DC link. Moreover, the active power loop becomes a second order system whose damping can be programmed freely.

Industrial low-power wireless mesh networks are shifting towards time synchronized medium access control (MAC) protocols which are able to yield over 99.9% end-to-end reliability, and radio duty cycles well below 1%. In these networks, motes use time slots to communicate, and neighbor motes maintain their clocks' alignment, typically within 1ms. Temperature, supply voltage and fabrication differences cause the motes' clocks to drift with respect to one another. Neighbor motes need to resynchronize periodically through pairwise communication. This period is typically determined a priori, based on the worst case drift. In this article, we propose a novel technique which measures and models the relative clock drift between neighbor motes, thereby reducing the effective drift rate. Instead of resynchronizing at a preset rate, neighbor motes re-synchronize only when needed. This reduces the minimum achievable duty cycle of an idle network by a factor of 10, which, in turn, lowers the mote power consumption, and extends the network lifetime. This Adaptive Synchronization is implemented as part of IEEE802.15.4e in the OpenWSN protocol stack, and is validated through extensive experimentation.

In this paper, we exploit the characteristics of physical layer network coding (PNC) in multicast short range communication (SRC) networks. We present a scalable scenario of partially overlapping SRC networks, where collisions are resolved through indirect inter-group cooperation based on the features of PNC. Our scenario consists of a central network and several peripheral networks. In our previous work we proved that the central network presents significant gains in terms of throughput, delay and energy efficiency when applying the proposed scheme. Here we explore the impact of that scenario on the peripheral networks through a decomposition approach and we prove that they also present significant performance gains.

This paper presents the FPGA design of an interference-aware digital front end tailored for heterogeneous multi-cell LTE-based systems. A resource-optimized RTL architecture has been implemented and validated under realistic operating conditions using the GEDOMIS® testbed. The parallelization and concurrent resource utilization of the joint synchronization and interference detection processing blocks is covered with low-level details.

The use of Wireless Sensor Networks (WSNs) are a promising technology that can enhance various aspects of today’s electric power systems, including generation, delivery, and utilization, making them a vital component of the next-generation electric power system, the smart grid. However, harsh and complex electric-power-system environments pose great challenges in the reliability of WSN communications in smartgrid applications. This paper presents wireless sensors with magnetic harvesting capabilities deployed along Underground High Voltage Power Lines (UHVPL) to allow long-lasting operation. The paper includes an overview of the communication protocol that optimizes sensor node coordination in linear array arrangements. Based on an optimal time synchronization method, the wireless sensors can self-adjust the communication timing in order to minimize the total power consumption. In addition, the paper provides a description of a linear sensor network under test, the results and discussions concerning network reliability and power efficiency.

Ambient Intelligence is a new paradigm in which environments are sensitive and responsive to the presence of people. This is having an increasing importance in multimedia applications, which frequently rely on sensors to provide useful information to the user. In this context, multimedia applications must adapt and personalize both content and interfaces in order to reach acceptable levels of context-specific quality of service for the user, and enable the content to be available anywhere and at any time. The next step is to make content available to everybody in order to overcome the existing access barriers to content for users with specific needs, or else to adapt to different platforms, hence making content fully usable and accessible. Appropriate access to video content, for instance, is not always possible due to the technical limitations of traditional video packaging, transmission and presentation. This restricts the flexibility of subtitles and audio-descriptions to be adapted to different devices, contexts and users. New Web standards built around HTML5 enable more featured applications with better adaptation and personalization facilities, and thus would seem more suitable for accessible AmI environments. This work presents a video subtitling system that enables the customization, adaptation and synchronization of subtitles across different devices and multiple screens. The benefits of HTML5 applications for building the solution are analyzed along with their current platform support. Moreover, examples of the use of the application in three different cases are presented. Finally, the user experience of the solution is evaluated.

In this paper, we address the analysis of human actions by comparing different performances of the same action executed by different actors. Specifically, we present a comparison procedure applied to the walking action, but the scheme can be applied to other different actions, such as bending, running, etc. To achieve fair comparison results, we define a novel human body model based on joint angles, which maximizes the differences between human postures and, moreover, reflects the anatomical structure of human beings. Subsequently, a human action space, called aSpace, is built in order to represent each performance (i.e., each predefined sequence of postures) as a parametric manifold. The final human action representation is called p-action, which is based on the most characteristic human body postures found during several walking performances. These postures are found automatically by means of a predefined distance function, and they are called key-frames. By using key-frames, we synchronize any performance with respect to the p- action. Furthermore, by considering an arc length parameterization, independence from the speed at which performances are played is attained. As a result, the style of human walking can be successfully analysed by establishing the differences of the joints between a male and a female walkers.

In this article we present our ongoing work on expressive /nperformance analysis for violin and string ensembles, in terms of /nsynchronization in intonation, timing, dynamics and articulation. Our current /nresearch objectives are outlined, along with an overview for the methods used /nto achieve them; finally, focusing on the case of intonation synchronization in /nviolin duets, some preliminary results and conclusions based on experimental /nrecordings are discussed. The work presented on this document has been partially supported by the EU-FP7 /nICT SIEMPRE project.