Bifurcations in the theory of current transfer to cathodes of dc discharges..
Bifurcations in the theory of current transfer to cathodes of dc discharges and transitions between different modes
Concentration of electrical current onto the surface of electrodes of gas discharges in well-deﬁned regions, or current spots, is often the rule rather than the exception. These spots occur on otherwise uniform electrode surfaces, a regime where one might expect a uniform distribution of current over the surface. In many cases, multiple spots may appear, forming beautiful patterns and surprising the observer. Theory of different modes to current transfer to electrodes of gas discharges is an important part of gas discharge theory in general and is needed for applications.
Modern theoretical description of spots and spot patterns on electrodes of dc glow and arc discharges is based on the multiplicity of solutions: an adequate theoretical model must in some cases allow multiple steady-state solutions to exist for the same conditions (in particular, for the same discharge current I), with different solutions describing the spotless (diffuse) mode of current transfer and modes with different spot configurations. The cornerstone of the theory is the existence of bifurcations of steady-state solutions. Unfortunately, this question has not been addressed in experimental publications on observations of transitions between spotless mode and modes with different spot configurations.
Our goal was to analyse these observations with the aim to identify eventual bifurcations. We have employed a basic numerical model of glow microdischarges, which includes a single ionization channel and a single ion species, and a detailed model, which accounts for different ionization channels, different ion and excited species, and nonlocality of electron transport and kinetics.
We have computed the relevant bifurcations and spot patterns, and found that the latter conform to spot patterns observed in the course of the corresponding transitions in the experiment. While the comparison between the theory and the experiment still remains qualitative, the agreement is convincing and lends further support to the theory.
O projeto SoMovEd procura introduzir ideias inovadoras no ensino universitário particularmente com o desenvolvimento de atividades “em movimento”, ou seja, atividades fora da sala-de-aula. Neste sentido o projeto procura desenvolver, implementar e disseminar inovação através da introdução do “MOBILE SOCIAL EDUCATION (MmsED) MODEL” no ensino superior. A sua caraterística principal é organizar os process(...)
Genetics of the HLA System and its contribution to the clinical and anthropological research of the population being studied (MAC/2.3/A6), developed between 2002 and 2005, financed by the community Initiative interreg III B Madeira-Açores-Canarias
UMa participates in ENSEC, which is a European Union funded project, running between Nov. 2017 to May 2020, and it is focused on the development of a European Study Program for an International Master’s Degree for the Environmental Security Sector. This project has two UMa lecturers and a Technician participating in the project who are dedicated to the development of guidelines for users of the learnin(...)
APOGEO MAC - Agricultura de precisão para o melhoramento da produção de vinho na Macaronésia. Programa: PCT-MAC 2014-2020.
Caracterização e conservação dos principais recursos genéticos vegetais tradicionais e estratégicos da RAM. Programa: PRODERAM 2020.
IMPACT III: – Impacto da Tecnologia na Qualidade do Vinho Madeira. Programa: PROCiência2020.
AROMA: Novos designs de sensores em fibra ótica para a deteção de compostos de AROMA. Programa: CENTRO 2020 + FCT
Contribución al ahorro hídrico en cultivos estratégicos para el sector primario de Canarias y Madeira mediante la aplicación de productos y extractos naturales bioactivos con propiedades osmoprotectoras. Programa: MAC 2014-2020.
CASBio - Avaliação e monitorização da Agrobiodiversidade e da Sustentabilidade dos Agrossistemas nos novos cenários climáticos. Programa: Operativo Madeira 14-20 da RAM.
A docente da Faculdade de Artes e Humanidades da Universidade da Madeira (FAH-UMa), Cristina Santos Pinheiro, obteve aprovação para financiamento da Fundação para a Ciência e Tecnologia como Investigadora Responsável do Projeto “Gynecia: Rodrigo de Castro Lusitano e a tradição médica antiga sobre ginecologia e embriologia”, no valor de cerca de 202.000€.
O financiamento, por três anos, r(...)
Beautiful patterns on anodes of DC glow discharges have been observed for over a century. In addition to being of significant theoretical interest by themselves, self-organized patterns on liquid anodes of atmospheric pressure glow microdischarges reveal a non-trivial cancer-inhibiting capability.
Our goal was to compute self-organized patterns of spots on a flat metallic anode of a glow dischar(...)
Efficient methods of modelling of electric arcs in high-pressure environment are of high importance for many technical devices, and the interaction of arc plasmas with electrodes, in the first place, the cathode, is currently a bottleneck. This explains a surge of interest in plasma-electrode interaction inhigh-pressure arc discharges in the scientific community that has occurred over the past couple o(...)
Understanding of mechanisms of operation of cathodic spots of vacuum arc discharges, including the role of explosive electron emission, is a challenging topic of high scientific interest and importance for applications. We conducted this research on the suggestion of, and in collaboration with, colleagues from Siemens Corporate Technology (Erlangen, Germany), one of the aims being application of result(...)
Genes and Hypertension in Madeira, financed by “Intervir+ (European Regional Development Fund – FEDER)”, aiming at detecting an association between gene polymorphism (hypertension candidates) and the existence of hypertension in Madeira.
Genes in Madeira and Coronary Disease, financed by “Intervir+ (European Regional Development Fund – FEDER)”, aiming to investigate about the genetic cause (polymorphism) of the coronary disease in Madeira Island.
Diversity of the HLA System in the Portuguese Population, developed between 1999 and 2003, financed by the European Social Fund through the multifund Operational Programme of Madeira.
Genetic Diversity of the HLA System in African Population (POCTI/BIA-BCM/60440/2004), under development since January 2005 and financed by FCT.
Enhancing Mathematics Learning @Free State (EML@FS) is a training programme for math teachers. Its main goal is to contribute to the improvement of students’ learning and to the development of their math skills, destined to 4th grade teachers of Free Stare Procinve – South Africa.
For this purpose, the following objectives have been set: to reinforce the mathematic and didactic knowledge of tea(...)
The project “Production of educational Socio-technological artefacts and training of teachers in Networking” (“Produção De Artefatos Educacionais Sociotecnológicos E Formação De Professores Em Rede”) is an opportunity for a partnership between the CIE-UMa and the University of the state of Bahia – UNEB (BR). Its main goal is to understand how and in what measure the collaborative production of educatio(...)
ANAM Project, 2011-2014 – Study of the Passenger’s Profile, by António Almeida
Event dedicated to the analysis in infinite dimension and applications, specifically fractional Differential equations and Mittag-Leffler analysis.
Researchers at GAUMa are responsible for 5 new entrees in the new Encyclopedic Dictionary of Madeira: 1) Astronomy; 2) International Year of Astronomy 2009; 3) Astronomy Group of the University of Madeira; 4) William Kingdom Clifford; 5) William Thomson (Lord Kelvin).
Annual event - "Astronomy Week". This is an event which has been held since 2001 with the aim of, during a week, disclosing and promoting Astronomy alongside to the different schools in Madeira as well as the public in general.
Study of Primordial Black Holes (PBHs): PBHs may have formed during the early stage of the Universe. At GAUMa we study theoretically its creation mechanisms, distribution throughout the Universe and eventual detection. PBHs allow us to track the primordial Universe and are pointed as the sources of the recently detected gravitational waves.
Setup of the Astronomical Observatory on the Island of Madeira with the potential of using it for research work in collaboration with other institutions. It is also intended that the observatory be used for observation sessions by students from different schools in the island as well as by the public in general, and that it can work as a promotion vector for scientific tourism.
Subjects such as individual talent and collective intelligence, originality and cooperation will be worked on. In this context, research is justified because it is seen as a key strategy in the process of developing creative people and sustainable organizations.
A collection made in collaboration with the Baltazar Dias Theater, in the framework of the celebrations marking the 130th anniversary of its opening. The collection aims to disseminate the unpublished and forgotten works of the dramatic genre of Madeiran authors.
Project in collaboration with the Municipality of Funchal that intends to inform children and adolescents the results of the investigations carried out within the ambit of the DEM. Reviewing the knowledge about the archipelago, almost 600 years since its discovery, represents opening doors for the future. Consisting of ten volumes with themes from economics to urbanism, from literature to history, the (...)
A project in collaboration with the Municipal Theater Baltazar Dias and the Municipality of Funchal, that aims to disseminate to the general public the knowledge produced during the elaboration of the DEM. The conferences are of multidisciplinary nature, contemplating several monthly events. This event was classified by Jornal da Madeira, as the "cultural event of the year 2017", and will continue, in (...)
Integrated in the “Aprender Madeira” Project, the Encyclopedic Dictionary proposes to update, synthesize, expand, understand and disseminate, in a contemporary perspective and with scientific rigor and pedagogical sense, knowledge accumulated about Madeira, seeking to join in the wake of those who, over the past centuries, have researched and written about Madeira.
The online and printed edition of authors and other relevant works for the knowledge of the literary heritage of Madeira and for a renewed vision of Portuguese literature as a whole. The main objective is to provide bibliographies, data and primary sources for students, professors and researchers in the area, as well as to disseminate an important collection for literature and culture, for the history (...)