On computational issues for stability analysis of LPV systems using parameter dependent Lyapunov functions and LMIs

This paper deals with the robust stability analysis of linear systems, subject to time-varying parameters. The Parameter Dependent Lyapunov Function are considered, assuming that the temporal derivative of the parameters are bounded. Some computational issues are discussed, which are present in Linear Matrix Inequality (LMI) based approaches and are exacerbated as the quantity of time-varying parameters increases. A possible solution to deal with issues is proposed by modifying the inclusion of the information regarding the time-derivative bounds. Complexity in the number of LMIs constraints can be reduced from very complex to linear. Numerical examples are provide to illustrate the advantages of the proposed methodology.Comment: 12 pages, 2 figures, 8 table

Fuzzy control turns 50: 10 years later

In 2015, we celebrate the 50th anniversary of Fuzzy Sets, ten years after the main milestones regarding its applications in fuzzy control in their 40th birthday were reviewed in FSS, see [1]. Ten years is at the same time a long period and short time thinking to the inner dynamics of research. This paper, presented for these 50 years of Fuzzy Sets is taking into account both thoughts. A first part presents a quick recap of the history of fuzzy control: from model-free design, based on human reasoning to quasi-LPV (Linear Parameter Varying) model-based control design via some milestones, and key applications. The second part shows where we arrived and what the improvements are since the milestone of the first 40 years. A last part is devoted to discussion and possible future research topics.Guerra, T.; Sala, A.; Tanaka, K. (2015). Fuzzy control turns 50: 10 years later. Fuzzy Sets and Systems. 281:162-182. doi:10.1016/j.fss.2015.05.005S16218228

Numerical investigation of aerodynamic noise irradiate by transverse prismatic bars.

O ruído aerodinâmico é uma fonte de ruído relevante em automóveis e domina a pressão sonora total no interior do habitáculo em velocidades de cruzeiro acima dos 110km/h superando as contribuições sonoras oriundas da rodagem e do conjunto motopropulsor. Acessórios externos como os racks de teto podem irradiar ruído aerodinâmico com características tonais em adição ao ruído de banda larga, configurando assim um dos problemas mais críticos para o desempenho de aeroacústica de um veículo. Ciente das vantagens de comprovar o desempenho destes acessórios ainda nas fases inicias do projeto, optou-se por analisar, via método híbrido de aeroacústica computacional, o ruído irradiado por cilindros submetidos a escoamento de ar transversal em regime subsônico e em diferentes configurações pelo fato destes possuírem vasta documentação técnica disponível e também por irradiarem ruído aerodinâmico com características semelhantes ao ruído emitido pelas barras transversais dos racks de teto. O método de Lattice-Boltzmann e a analogia acústica de Ffowcs-Williams e Hawkings foram aplicados nas simulações numéricas de casos como o de um cilindro isolado e o de cilindros alinhados em tandem em túnel de vento anecóico e o de um cilindro em túnel de vento semi-anecóico, sendo que, após a obtenção das curvas de densidade espectral de potência do ruído irradiado, utilizou-se a análise de decomposição em modos dinâmicos para determinar as estruturas coerentes presentes no escoamento em cada uma das frequências de interesse. As frequências fundamentais e as harmônicas dos tonais foram capturadas com precisão de ao menos 95% e as amplitudes das curvas do ruído em campo afastado mostram boa aproximação com os testes de referência. As estruturas coerentes resultantes da análise de decomposição em modos dinâmicos também apresentaram boa aproximação com a física dos problemas e a natureza do ruído aerodinâmico. O método abordado mostrou-se eficaz e versátil em aplicações de aeroacústica e aerodinâmica servindo de ferramenta importante na solução de problemas nas fases iniciais do projeto onde o custo de modificação é baixo e a facilidade de modificação elevada.Aerodynamic noise is a relevant source of noise in ground vehicles, dominating the total sound pressure level inside the cabin at cruising speeds above 110km/h and exceeding the acoustic contributions of the road and powertrain. External accessories, such as roof racks, can irradiate aerodynamic noise with tonal characteristics in addition to the broadband noise, being this one of the most critical problems for vehicle\'s aeroacoustic performance. Aware of the advantages of verifying the performance of these accessories in the early stages of the project, it was decided to analyze, via hybrid computational aeroacoustics method, the noise radiated by transverse cylinders in subsonic air flow and in different configurations due to the fact that they have a wide range of technical documentation available and also for radiating aerodynamic noise with similar characteristics to the noise emitted by the roof rack crossbars. The Lattice-Boltzmann method and the Ffowcs-Williams and Hawking acoustic analogy have been applied in numerical simulations of cases such as one cylinder and two cylinders arranged in tandem in 12qan anechoic wind tunnel and that of a cylinder in a semi-anechoic wind tunnel and, after obtaining the power spectral density curves of the radiated noise the dynamic mode decomposition analysis was applied to determine the coherent structures present in the flow at each of the frequencies of interest. The fundamental frequencies and the harmonics of the tonal noise have been captured with an accuracy of at least 95% and the amplitudes of the far field noise power spectral density curves shown good approximation with the reference tests. The coherent structures resulting from the dynamic mode decomposition analysis also presented a good approximation with the physics of the simulated cases and with the nature of the aerodynamic noise. The method employed in the present investigation proved to be effectiveand versatile in aeroacoustics and aerodynamics applications, serving as important tool in solving problems in the early phases of the project where the cost of modification is low and the ease for modification high

An Artistic And Curatorial Installation In Virtual Reality: The Development Of An Artistic Low-cost Interface At University

The objective of this study is to report the learning experience and development of a mobile art installation of low-cost immersive virtual reality using technologies for the development of digital games. Through virtual simulation of the use of a common space in the university, the art gallery of the Guignard School of art at UEMG in Brazil. The article describes how the installation was developed as well as how the users interactions challenges have been solved in the virtual environment, since to make the movement of users within the virtual environment possible there were not external interfaces such as joysticks or motion cameras to interact. The development of the installation, which provided greater visibility to the extension project called 'Living Room', is the main reason for the creation of the installation and for elaborating questions on the relationship between virtual exhibition design and interactivity. © 2016 IEEE.20921415th Adjunct IEEE International Symposium on Mixed and Augmented Reality, ISMAR-Adjunct 201618 September 2016 through 23 September 201612630