4,281 research outputs found
Domain wall description of superconductivity
In the present work we shall address the issue of electrical conductivity in
superconductors in the perspective of superconducting domain wall solutions in
the realm of field theory. We take our set up made out of a dynamical complex
scalar field coupled to gauge field to be responsible for superconductivity and
an extra scalar real field that plays the role of superconducting domain walls.
The temperature of the system is interpreted through the fact that the soliton
following accelerating orbits is a Rindler observer experiencing a thermal
bath.Comment: 9 pages, 5 figures, Latex. Version to appear in PL
Model-driven GUI generation and navigation for android BIS apps
This paper presents our approach for producing graphical user interfaces (GUIs) for functionally rich business information system (BIS) prototypes, upon a mobile platform. Those prototypes are specified with annotated UML class diagrams. Navigation in the generated GUIs is allowed through the semantic links that match the associations and cardinalities among the conceptual domain entities, as expressed in the model. We start by reviewing the Android scaffolding for producing flexible GUIs for mobile devices. The latter can present rather different displays, in terms of size, orientation and resolution. Then we show how our model-based generative technique allows producing prototypes that match both the Android GUIs requirements, while implementing our model-driven approach for user navigation.info:eu-repo/semantics/publishedVersio
Moving to the cloud: Estimating the internet connection bandwidth
IT Infrastructures (ITIs) have long been understood in terms of people and resources such as servers, routers, firewalls and operating systems, among other components, running and providing services inside the organization. The need to reduce the cost of ITI ownership, by offloading its capacity to third parties, has motivated organizations to consider the Cloud Computing alternative. The main drawback they face when opting for the cloud is the dependency on and requirements of the internet connection, since it must be fast and reliable. This paper addresses this concern by providing guidelines for estimating internet connection bandwidth requirements for a prototypical cloud-based organization represented by means of an IT infrastructure pattern. ITI patterns are reusable and proven solutions to support the ITI design process and to facilitate the communication among stakeholders.info:eu-repo/semantics/acceptedVersio
Avaliação directa da toxicidade de águas residuais: um caso de estudo
A avaliação global das águas residuais deve integrar ensaios ecotoxicológicos complementando a caracterização química, especialmente no caso de águas residuais complexas. O projecto ECORIVER, que decorreu na Bacia do Rio Trancão, integrou o estudo ecotoxicológico e físico-químico de águas residuais de empresas de vários sectores industriais. Apresentam-se resultados relativos à avaliação ecotoxicológica de águas residuais de 17 empresas através da utilização de ensaios agudos e crónicos, com diferentes espécies: a bactéria Vibrio fischeri, a alga Pseudokircheneriella subcapitata, os crustáceos Thamnocephalus platyurus e Daphnia magna, e a planta Lemna minor. A análise dos resultados permitiu concluir que uma bateria de ensaios com uma bactéria, um crustáceo e uma alga, é representativa. Concluiu-se ainda que a utilização da abordagem ecotoxicológica é uma mais-valia para a avaliação do perigo e do risco de descargas para o meio hídrico e pode contribuir para um mais correcto estabelecimento de condições de descarga, com o objectivo de atingir a boa qualidade ecológica das massas de água. A monitorização e a gestão ambiental podem utilizar esta ferramenta com vantagens
Books that Matter. The Case of Tocqueville’s Democracy in America
This article addresses a puzzle in the history of academic disciplines: Why is Alexis de Tocqueville’s Democracy in America, once considered a sociological classic, nowadays mostly praised as a classic in political philosophy? Existing approaches emphasize either aspects internal to the text or to the figure of the author, or external factors such as historical contexts and disciplinary dynamics. Our explanation questions the assumption that texts are stable and explores the pragmatic interplay between text-artifact-metaphor. The result is a pragmatic genealogy of the successive material incarnations of Democracy since 1945. This allows us to account for the various meanings that have been associated with Democracy (and Tocqueville) at key historical moments in terms of the cultural work of collectives of agents around the text and its material form so as to make it the icon of certain political and disciplinary projects
Industrial robotic arm in machining process aimed to 3D objects reconstruction
Industrial robots are a technology which is highly present in industry and can perform several tasks, namely machining activities. Different than CNC machines, which work with G-code and have available several software applications to generate the machine code, there is a lack of software for robotic arms, in addition to each application depending on its own language and software. This work studied a way to use different robotic arms for 3D part machining processes, to perform 3D objects reconstruction obtained through a low-cost 3D scanner. Dealing with the 3D reconstruction by integrating 3D acquisition and robotic milling with software available on the market, this paper presents a system that acquires and reconstructs a 3D object, in order to seek greater flexibility with lower initial investments and checking the applicability of robot arm in these tasks. For this, a 3D object is scanned and imported to a CAD/CAM software, to generate the machining toolpath, and a software application is used to convert the G-code into robot code. Several experiments were performed, using an ABB IRB 2600 robot arm, and the results of the machining process allowed to validate the G-code conversion and milling process using robotic arms, according to the proposed methodology. © 2021 IEEE.This work has been supported by FCT – Fundac¸ao para a ˜
Ciencia e Tecnologia within the Projects UIDB/50014/2020 ˆ
and UIDB/05757/2020.info:eu-repo/semantics/publishedVersio
Improving IT infrastructures representation: A UML profile
IT infrastructures are most times informally modeled. The resulting models are ambiguous to stakeholders, cannot be checked for validity, and therefore are unable to play their important role in design, deployment and maintenance activities. The main reason for such a poor state-of-the-art lies mainly in the absence of a modeling language capable of representing IT infrastructures at the required level of abstraction. Indeed, existing candidate languages are too abstract, as shown in this paper by reviewing their metamodels. The present paper mitigates this problem by proposing a UML profile to describe the semantics of an IT infrastructure.info:eu-repo/semantics/publishedVersio
Improving IT infrastructures representation: A UML profile
IT infrastructures are most times informally modeled. The resulting models are ambiguous to stakeholders, cannot be checked for validity, and therefore are unable to play their important role in design, deployment and maintenance activities. The main reason for such a poor state-of-the-art lies mainly in the absence of a modeling language capable of representing IT infrastructures at the required level of abstraction. Indeed, existing candidate languages are too abstract, as shown in this paper by reviewing their metamodels. The present paper mitigates this problem by proposing a UML profile to describe the semantics of an IT infrastructure.info:eu-repo/semantics/publishedVersio
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