La conexión entre los Objetivos de Desarrollo Sostenible Nº4, Nº12 y la contaminación marina por plásticos radica en la necesidad de adoptar competencias de formación en contaminación marina y patrones de producción y consumo más responsables con el fin de reducir los plásticos procedentes de los buques, contribuyendo directamente a la mitigación de la contaminación en los océanos por parte de estos. Como punto de partida, en el presente artículo se trata de definir la basura marina plástica y abordar los problemas que causa en el medio ambiente. Posteriormente, se analiza la regulación de los desechos marinos procedentes de los buques haciendo hincapié en las medidas adoptadas por la Organización Marítima Internacional para regular la basura marina y su contribución a los citados Objetivos de Desarrollo Sostenible. Finalmente, como una posible solución a la reducción de la contaminación marina se lleva a cabo una comparativa entre la «Economía lineal» y la «Economía circular», concluyendo que un futuro sostenible pasa indefectiblemente por un modelo de educación de economía circular. [Abstract] The connection between Sustainable Development Goals No. 4, No. 12 and marine plastic pollution lies in the need to adopt training skills in marine pollution and more responsible production and consumption patterns to reduce plastics from ships, contributing directly to the mitigation of pollution in the oceans by them. As a starting point, this article seeks to define plastic marine litter and address the problems it causes in the environment. Subsequently, the regulation of marine waste from ships is analyzed, emphasizing the measures adopted by the International Maritime Organization to regulate marine litter and its contribution to the Sustainable Development Goals that appear with numbers 4 and 12. Finally, as a possible solution to reducing marine pollution, a comparison is carried out between the «Linear Economy» and the «Circular Economy», concluding that.

Endodontic rotary file instruments used to treat root canals in dentistry suffered breakthrough transformations in recent years when stainless steel was replaced by Nickel-Titanium (NiTi). NiTi alloys used in Endodontics possess superelastic properties at body temperature (37C) that bring many advantages on the overall performance of the root-canal treatment. They can follow curved root canals more easily than stainless steel instruments and have been reported to be more effective in the removal of the inflamed pulp tissue and protection of the tooth structure. However, these instruments eventually fracture under cyclic bending loading due to fatigue, without any visible signals of degradation to the practitioner. This problem brought new challenges on how new instruments should be tested, as NiTi alloys are highly non-linear and present a large hysteresis cycle in the Elastic domain. Current existing standards are only available for Stainless Steel testing. Thus, many authors have attempted to design systems that can test NiTi endodontic files under fatigue loads. However, no approach has been universally adopted by the community yet, as in most cases they are based on empirical set ups. Following a more systematic approach, this work presents the results of rotary fatigue tests for several NiTi wires from different manufacturers (MemryTM and EuroflexTM). The tests were done on a versatile fully automatic rotary bending testing machine. The formulation is also presented, where the material strength reduction can be quantified from the determination of the strain and the number of cycles until failure.

In this work, a simple and efficient finite element model is applied to the vibration analysis of active–passive damped multilayer sandwich plates/shells with a viscoelastic core, sandwiched between functionally graded material (FGM) layers, and including piezoelectric layers. Both the FGM and the piezoelectric layers are modelled using the classical plate theory and the core is modelled using Reddy’s third-order shear deformation theory. The sandwich finite element is obtained performing the assembling of N “elements” through the thickness, by using specific assumptions on the displacement continuity at the interfaces between layers. To achieve a mechanism for the active control of the structural dynamics response, a feedback control algorithm is used, coupling the sensor and active piezoelectric layers. The dynamic analysis of the sandwich plate/shell structures is conducted in the frequency domain to obtain the natural frequencies and the loss factors of the viscoelastic core and in time domain for the steady state harmonic motion. For both analyses, a finite element code has been implemented. The model is applied in the solution of some illustrative examples and the results are presented and discussed.

A segurança da navegação está regulamentada por diversas organizações, por forma a criar padrões seguros de operação. Adicionalmente, devido à pandemia, foram criadas orientações específicas para salvaguardar a saúde dos marítimos desta catástrofe mundial. A Gestão dos Recursos da Ponte é determinante para a segurança da navegação, garantindo assim a salvaguarda da vida dos marítimos e a proteção do meio ambiente. O fator humano é o elemento determinante para essa gestão, não só pelas competências técnicas dos marítimos, mas também pelas suas competências não-técnicas. A pandemia originou uma redução do tráfego marítimo, em particular no segmento dos navios de passageiros, contribuindo para a redução de encalhes e colisões, mas por outro lado, exigiu mais das competências não técnicas dos marítimos

This paper focuses on green shipping and its’ influence on the sustainable economy and environmental performance. Based on the green shipping approach, this empirical study examines a survey sample of 193 responses from Portuguese and Spanish executive managers and uses exploratory factor analysis and structural equation model. The Green shipping approach supports the green theory. The results show the importance of green efficiency, green management, and pollution impact. The confirmation of the sizeable influence of green shipping on the sustainable economy and environmental performance constructs constitutes a major contribution to the literature. Green management and green efficiency contribute to controlling the impact of pollution with practical effects on economic sustainability. Another contribution arises from the fact that tax and financial incentives and environmental sustainability regulations indicate the relevance of the pollution impact and sustainable economy.

We present a framework to describe completely general first-order perturbations of static, spatially compact, and locally rotationally symmetric class II spacetimes within the theory of general relativity. The perturbation variables are by construction covariant and identification gauge invariant and encompass the geometry and the thermodynamics of the fluid sources. The new equations are then applied to the study of isotropic, adiabatic perturbations. We discuss how the choice of frame in which perturbations are described can significantly simplify the mathematical analysis of the problem and show that it is possible to change frames directly from the linear level equations. We find explicitly that the case of isotropic, adiabatic perturbations can be reduced to a singular Sturm–Liouville eigenvalue problem, and lower bounds for the values of the eigenfrequencies can be derived. These results lay the theoretical groundwork to analytically describe linear, isotropic, and adiabatic perturbations of static, spherically symmetric spacetimes

This paper addresses the strategic and tactical planning of a downstream oil supply chain (DOSC) subject to different sources of uncertainty. This problem is formulated as a mixed-integer linear programming (MILP) model, whereas uncertainty is tackled using chance constrained programming with fuzzy parameters. The MILP model aims at determining the network design and the products distribution plan in a cost-effective way. A real case study on the Brazilian oil industry is used to validate the model. The proposed model shows to be a valuable decision-support tool in order to aid the decision-making process in the strategic and tactical planning of real-life problems.

Frege’s theory is inconsistent (Russell’s paradox). However, the predicative version of Frege’s system is consistent. This was proved by Richard Heck in 1996 using a model-theoretic argument. In this paper, we give a finitistic proof of this consistency result. As a consequence, Heck’s predicative theory is rather weak (as was suspected).

Esta tese vai incidir na implementação de manutenção condicionada em alguns equipamentos novos e noutros já implantados na linha de produção de gelados de uma unidade industrial. A unidade fabril é composta por várias linhas de produção que fazem diferentes tipos de gelados. Cada uma das linhas tem várias máquinas que executam as diferentes tarefas de produção de gelados, começando pelo enchimento e passando sucessivamente pelo fecho, congelamento, embalamento e seguindo depois para a paletização onde os produtos são colocados em paletes para serem transportados para as câmaras frigoríficas de armazenagem. A tese começa por fazer uma breve introdução da história da manutenção, dos vários tipos existentes e das várias formas de implementação e execução. Considerando que a unidade fabril onde será implementada a manutenção condicionada é a Fábrica Olá foca a evolução da manutenção nesta unidade fabril e finalmente debruça-se na linha dos cornetos na qual estão a ser montados uma série de equipamentos para automatização da linha de embalagem. Esta montagem é feita em duas etapas e terá a duração total de 4 meses. Durante a sua execução vai ser feita a identificação e codificação de todos os equipamentos a instalar. Para cada um deles será feito um estudo para definir qual o tipo de manutenção mais adequado. Em função deste estudo serão criadas as tarefas de manutenção, endereçadas às pessoas responsáveis pela sua execução.