Modelling and Control of Shape Memory Alloy Actuators by using Preisach Model, Genetic Algorithm and Fuzzy Logic

Shapememoryalloy (SMA) actuators, which have the ability to return to a predetermined shape when heated, have many potential applications in aeronautics, surgical tools, robotics and so on. Nonlinearity hysteresis effects existing in SMA actuators present a problem in the motion control of these smart actuators. This paper investigates the control problem of SMA actuators in both simulation and experiment. In the simulation, the numerical Preisachmodel with geometrical interpretation is used for hysteresis modeling of SMA actuators. This model is then incorporated in a closed loop PID control strategy. The optimal values of PID parameters are determined by using geneticalgorithm to minimize the mean squared error between desired output displacement and simulated output. However, the control performance is not good compared with the simulation results when these parameters are applied to the real SMA control since the system is disturbed by unknown factors and changes in the surrounding environment of the system. A further automated readjustment of the PID parameters using fuzzylogic is proposed for compensating the limitation. To demonstrate the effectiveness of the proposed controller, real time control experiment results are presented.

RFID based Efficient Lighting Control

The Kyoto Protocol and the European Energy Performance of Buildings Directive put an onus on governments
and organisations to lower carbon footprint in order to contribute towards reducing global warming. A key
parameter to be considered in buildings towards energy and cost savings is its indoor lighting that has a major
impact on overall energy usage and Carbon Dioxide emissions. Lighting control in buildings using Passive
Infrared sensors is a reliable and well established approach; however, the use of only Passive Infrared does not
offer much savings towards reducing carbon, energy, and cost. Accurate occupancy monitoring information can
greatly affect a building’s lighting control strategy towards a greener usage. This paper presents an approach for
data fusion of Passive Infrared sensors and passive Radio Frequency Identification (RFID) based occupancy
monitoring. The idea is to have efficient, need-based, and reliable control of lighting towards a green indoor
environment, all while considering visual comfort of occupants. The proposed approach provides an estimated
13% electrical energy savings in one open-plan office of a University building in one working day. Practical
implementation of RFID gateways provide real-world occupancy profiling data to be fused with Passive
Infrared sensing towards analysis and improvement of building lighting usage and control.

Imaging adiabatic control of charge transfer in molecules

Charge transfer is a subfemtosecond process in molecules that creates chemical and electronic structure changes. At the quantum level the process can be coherently controlled by ultrashort light pulses. We show how the charge transfer process can be manipulated using a combination of dynamic and static fields and predict how this can be observed experimentally by imaging with photoionization.

Capability Curve Based Enhanced Reactive Power Control Strategy for Stability Enhancement and Network Voltage Management

Reactive power has become a vital resource in modern electricity networks due to increased penetration of distributed generation. This paper examines the extended reactive power capability of DFIGs to improve network stability and capability to manage network voltage profile during transient faults and dynamic operating conditions. A coordinated reactive power controller is designed by considering the reactive power capabilities of the rotor-side converter (RSC) and the grid-side converter (GSC) of the DFIG in order to maximise the reactive power support from DFIGs. The study has illustrated that, a significant reactive power contribution can be obtained from partially loaded DFIG wind farms for stability enhancement by using the proposed capability curve based reactive power controller; hence DFIG wind farms can function as vital dynamic reactive power resources for power utilities without commissioning additional dynamic reactive power devices. Several network adaptive droop control schemes are also proposed for network voltage management and their performance has been investigated during variable wind conditions. Furthermore, the influence of reactive power capability on network adaptive droop control strategies has been investigated and it has also been shown that enhanced reactive power capability of DFIGs can substantially improve the voltage control performance.

Tripping Control for Transient Stability in Coordinated Hydro and Wind Generation

Over-frequency generator tripping (OFGT) is used to cut off extra generation to balance power and loads in an isolated system. In this paper the impact of OGFT as a consequence of grid-connected wind farms and under-frequency load shedding (UFLS) is analysed. The paper uses a power system model to demonstrate that wind power fluctuations can readily render OFGT and UFLS maloperation. Using combined hydro and wind generation, the paper proposes a coordinated strategy which resolves problems associated with OFGT and UFLS and preserves system stability.

Dynamical symmetry breaking with optimal control: Reducing the number of pieces

We analyze the production of defects during the dynamical crossing of a mean-field phase transition with a real order parameter. When the parameter that brings the system across the critical point changes in time according to a power-law schedule, we recover the predictions dictated by the well-known Kibble-Zurek theory. For a fixed duration of the evolution, we show that the average number of defects can be drastically reduced for a very large but finite system, by optimizing the time dependence of the driving using optimal control techniques. Furthermore, the optimized protocol is robust against small fluctuations.

Virtual metrology enabled early stage prediction for enhanced control of multi-stage fabrication processes

Semiconductor fabrication involves several sequential processing steps with the result that critical production variables are often affected by a superposition of affects over multiple steps. In this paper a Virtual Metrology (VM) system for early stage measurement of such variables is presented; the VM system seeks to express the contribution to the output variability that is due to a defined observable part of the production line. The outputs of the processed system may be used for process monitoring and control purposes. A second contribution of this work is the introduction of Elastic Nets, a regularization and variable selection technique for the modelling of highly-correlated datasets, as a technique for the development of VM models. Elastic Nets and the proposed VM system are illustrated using real data from a multi-stage etch process used in the fabrication of disk drive read/write heads. © 2013 IEEE.

Control of harmonic generation from relativistic mirrors

We demonstrate for the first time that fine varying of the density gradient of a plasma mirror along with laser spatial phase on target allows total control over the harmonic generation mechanisms and harmonic spatial properties. An analytical model is also proposed. © OSA 2013.

In situ catalyst activity control in a novel membrane reactor-Reaction driven wireless electrochemical promotion of catalysis

A dual chamber membrane reactor was used in order to study the effect of macroscopically applied oxygen chemical potential differences to a platinum catalyst supported on a mixed oxygen ion and electronic conducting membrane. It is believed that the oxygen chemical potential difference imposed by the use of an oxygen sweep in one of the reactor chambers causes the back-spillover of oxygen species from the support onto the catalyst surface, resulting in the modification of the catalytic activity. The use of different sweep gases, such as ethylene and hydrogen was investigated as the means to reverse the rate modification by removing the spilt over species from the catalyst surface and returning the system to its initial state. Oxygen sweep in general had a positive effect on the reaction rate with rate increases up to 20% measured. Experimental results showed that hydrogen is a more potent sweep gas than ethylene in terms of the ability to reverse rate modification. A 10% rate loss was observed when using an ethylene sweep as compared with an almost 60% rate decrease when hydrogen was used as the sweep gas. © 2009 Elsevier Ltd. All rights reserved.

Wireless electrochemical modification of catalytic activity on a mixed protonic-electronic conductor

A novel approach to electrochemical modification of catalytic activity using a wireless configuration has been undertaken. This paper presents preliminary results on the modification of a platinum catalyst film supported on a pellet of Sr_0.97Ce_0.9Yb_0.1O_3-δ (SCYb), considered to be a mixed protonic-electronic conductor under reducing conditions. The wireless configuration utilises the mixed ionic and electronic conductivity of the supporting membrane to supply an ionic promoting species to the catalyst surface. Control of the flux of this species is achieved by adjusting the effective hydrogen chemical potential difference across the membrane in a dual-chamber reactor with one chamber acting as the "reaction side" and the other as the "sweep side". The reaction rate can be promoted by up to a factor of 1.6, for temperatures around 500 °C and low reactant concentrations, when hydrogen is introduced on the sweep side of the membrane reactor. The use of helium, moist helium and oxygen in helium as sweep gases did not modify the reaction rate. © 2007 Elsevier B.V. All rights reserved.

Tools and Environments for Networked Electronic Performance

A collection of software and hardware tools and environments that facilitate collective networked performance between electronic musicians. Tools include 'Chat Monkey', a live chat tool for performance, 'DMA Sequencing', a step sequencer using open sound control messaging and multi nodal control, 'tutti, duet, trio, solo, quartet', an ensemble management environment, and 'Por Larrañaga', a cigar box based electro-acoustic instrument with embedded sensors and controllers. Notable performances: w/BLISS, NCAD, Dublin, 1 March 2015; w/BLISS, NI Science Festival, Belfast, 21 Feb 2015

Real-space grids and the Octopus code as tools for the development of new simulation approaches for electronic systems

Real-space grids are a powerful alternative for the simulation of electronic systems. One of the main advantages of the approach is the flexibility and simplicity of working directly in real space where the different fields are discretized on a grid, combined with competitive numerical performance and great potential for parallelization. These properties constitute a great advantage at the time of implementing and testing new physical models. Based on our experience with the Octopus code, in this article we discuss how the real-space approach has allowed for the recent development of new ideas for the simulation of electronic systems. Among these applications are approaches to calculate response properties, modeling of photoemission, optimal control of quantum systems, simulation of plasmonic systems, and the exact solution of the Schrödinger equation for low-dimensionality systems.

Electronic health records for mobile citizens: a secure and collaborative architecture

Durante as ultimas décadas, os registos de saúde eletrónicos (EHR) têm evoluído para se adaptar a novos requisitos. O cidadão tem-se envolvido cada vez mais na prestação dos cuidados médicos, sendo mais pró ativo e desejando potenciar a utilização do seu registo. A mobilidade do cidadão trouxe mais desafios, a existência de dados dispersos, heterogeneidade de sistemas e formatos e grande dificuldade de partilha e comunicação entre os prestadores de serviços. Para responder a estes requisitos, diversas soluções apareceram, maioritariamente baseadas em acordos entre instituições, regiões e países. Estas abordagens são usualmente assentes em cenários federativos muito complexos e fora do controlo do paciente. Abordagens mais recentes, como os registos pessoais de saúde (PHR), permitem o controlo do paciente, mas levantam duvidas da integridade clinica da informação aos profissionais clínicos. Neste cenário os dados saem de redes e sistemas controlados, aumentando o risco de segurança da informação. Assim sendo, são necessárias novas soluções que permitam uma colaboração confiável entre os diversos atores e sistemas. Esta tese apresenta uma solução que permite a colaboração aberta e segura entre todos os atores envolvidos nos cuidados de saúde. Baseia-se numa arquitetura orientada ao serviço, que lida com a informação clínica usando o conceito de envelope fechado. Foi modelada recorrendo aos princípios de funcionalidade e privilégios mínimos, com o propósito de fornecer proteção dos dados durante a transmissão, processamento e armazenamento. O controlo de acesso _e estabelecido por políticas definidas pelo paciente. Cartões de identificação eletrónicos, ou certificados similares são utilizados para a autenticação, permitindo uma inscrição automática. Todos os componentes requerem autenticação mútua e fazem uso de algoritmos de cifragem para garantir a privacidade dos dados. Apresenta-se também um modelo de ameaça para a arquitetura, por forma a analisar se as ameaças possíveis foram mitigadas ou se são necessários mais refinamentos. A solução proposta resolve o problema da mobilidade do paciente e a dispersão de dados, capacitando o cidadão a gerir e a colaborar na criação e manutenção da sua informação de saúde. A arquitetura permite uma colaboração aberta e segura, possibilitando que o paciente tenha registos mais ricos, atualizados e permitindo o surgimento de novas formas de criar e usar informação clínica ou complementar.

Transient analysis of variable-speed wind turbines at wind speed disturbances and a pitch control malfunction

As wind power generation undergoes rapid growth, new technical challenges emerge: dynamic stability and power quality. The influence of wind speed disturbances and a pitch control malfunction on the quality of the energy injected into the electric grid is studied for variable-speed wind turbines with different power-electronic converter topologies. Additionally, a new control strategy is proposed for the variable-speed operation of wind turbines with permanent magnet synchronous generators. The performance of disturbance attenuation and system robustness is ascertained. Simulation results are presented and conclusions are duly drawn. (C) 2010 Elsevier Ltd. All rights reserved.