OALib Journal期刊

ISSN: 2333-9721




4 ( 1 )

2019 ( 34 )

2018 ( 280 )

2017 ( 242 )


匹配条件: “Jo?o;” ,找到相关结果约121126条。
Application of a Computational Tool to Study the Influence of Worn Wheels on Railway Vehicle Dynamics  [PDF]
Joo Pombo
Journal of Software Engineering and Applications (JSEA) , 2012, DOI: 10.4236/jsea.2012.52009
Abstract: The search for fast, reliable and cost effective means of transport that presents better energy efficiency and less impact on the environment has resulted in renewed interest and rapid development in railway technology. To improve its efficiency and competitiveness, modern trains are required to travel faster, with high levels of safety and comfort and with reduced Life Cycle Costs (LCC). These increasing demands for vehicle requirements imposed by railway operators and infrastructure companies include maintaining the top operational speeds of trainsets during their life cycle, having low LCC and being track friendly. This is a key issue in vehicle design and in train operation since it has a significant impact on the safety and comfort of railway systems and on the maintenance costs of vehicles and infrastructures. The purpose of this work is to analyze how the wear progression on the wheelsets affects the dynamic behavior of railways vehicles and its interaction with the track. For this purpose a vehicle, assembled with new and worn wheels, is studied in realistic operation scenarios. The influence of the wheel profile wear on the vehicle dynamic response is assessed here based on several indicators used by the railway industry. The running stability of the railway vehicles is also emphasized in this study.
Nutritional Quality and Health Benefits of Vegetables: A Review  [PDF]
Joo Silva Dias
Food and Nutrition Sciences (FNS) , 2012, DOI: 10.4236/fns.2012.310179
Abstract: Vegetables are considered essential for well-balanced diets since they supply vitamins, minerals, dietary fiber, and phytochemicals. Each vegetable group contains an unique combination and amount of these phytonutriceuticals, which distinguishes them from other groups and vegetables whithin their own group. In the daily diet vegetables have been strongly associated with improvement of gastrointestinal health, good vision, and reduced risk of heart disease, stroke, chronic diseases such as diabetes, and some forms of cancer. Some phytochemicals of vegetables are strong antioxidants and are thought to reduce the risk of chronic disease by protecting against free radical damage, by modifying metabolic activation and detoxification of carcinogens, or even by influencing processes that alter the course of tumor cells. All the vegetables may offer protection to humans against chronic diseases. Nutrition is both a quantity and a quality issue, and vegetables in all their many forms ensure an adequate intake of most vitamins and nutrients, dietary fibers, and phytochemicals which can bring a much-needed measure of balance back to diets contributing to solve many of these nutrition problems. The promotion of healthy vegetable products has coincided with a surging consumer interested in the healthy functionality of food. Because each vegetable contains a unique combination of phytonutriceuticals, a great diversity of vegetables should be eaten to ensure that individual’s diet includes a combination of phytonutriceuticals and to get all the health benefits. This article make a review and discusses the nutritional quality and health benefits of the major groups of vegetables. More interdisciplinary work is required that involves nutritional and food scientists as well as others from biomedical fields to ascertain the thrue function of specific phytonutriceuticals.
Neutrino Oscillations and Superluminal Propagation, in OPERA or Otherwise  [PDF]
Joo Magueijo
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.41013

We digress on the implications of recent claims of superluminal neutrino propagation. No matter how we turn it around such behaviour is very odd and sits uncomfortably even within far-fetched theories. In the context of non-linear realizations of the Lorentz group (where superluminal misbehaviour is run of the mill) one has to accept rather contrived constructions to predict superluminal properties for the neutrino. The simplest explanation is to require that at least one of the mass states be tachyonic. We show that due to neutrino mixing, the flavor energy does not suffer from the usual runaway pathologies of tachyons. For non-tachyonic mass states the theories become more speculative. A neutrino specific dispersion relation is exhibited, rendering the amplitude of the effect reasonable for a standard Planck energy. This uses the fact that the beam energy is close to the geometrical average of the neutrino and Planck mass; or, seen in another way, the beam energy is unexceptional but its gamma factor is very large. A dispersion relation crossing over from a low energy bradyonic branch to a high energy tachyonic one is also considered. We comment on consistency with SN 1987Awithin these models.

Reflections on the Green Economy (Redemption of the Principles of Mill and Pigou): A View of a Brazilian Environmentalist  [PDF]
Joo Batista Drummond Camara
Journal of Environmental Protection (JEP) , 2014, DOI: 10.4236/jep.2014.512113
Abstract: The current context of global efforts in the pursuit of sustainable development can be characterized by the perception of the scientific-technological losses of ecosystems and ecosystem services and their consequences for the survival of humanity in the face of threats of imbalances in the basic conditions for survival such as food production, the environmental quality, natural control of pests and diseases, loses of biodiversity and climate changes. Some recent initiatives at global, regional and local level are pointed and some conceptual trends and deployment strategies advance towards the consolidation of the principles of sustainable development, despite several difficulties for effectively reaching its goals. The trend of gradual changes in the models of developing nations and in the patterns of production and consumption is portrayed objectively, seeking to correlate with principles of environmental economics and green economy, since Cecil Pigou and Stuart Mill principles to recent researches as Kenneth Boulding, Herman Daly, Nicholas Georgescu-Rogen, Franz Capra, Ignacy Sachs, Edgar Morin, beyond others. The ability of the United Nations and governments to intervene in neoliberal logic aiming wider benefit to society and the reduction of the negative effects of market distortions, as striking on the global stage, represents a true redemption of the principles advocated by Cecil Pigou, at the beginning of the last century, both for the global economy and for their effects on environmental and social conflicts, social exclusion resulting from the current economic systems which are not necessary new strategies, principles, or economic formulas, but decision making to tackle the market with seriousness to promote equity, social justice and environmental sustainability, without sacrificing progress and development, as evident in the current discussion of social inclusion and the convergence of individual and collective interests, so far in the development model based on increasing production and consumption, yet with little environmental responsibility.
Idempotent Generated Endomorphisms of an Independence Algebra
Joo Araújo
Mathematics , 2011, DOI: 10.1007/s00233-002-0020-6
Abstract: The aim of this note is to give a direct proof for the following result proved by Fountain and Lewin: {\em Let $\alg$ be an independence algebra of finite rank and let $a$ be a singular endomorphism of $\alg $. Then $a=e_1... e_n$ where $e^2_i=e_i$ and $rank(a)=rank(e_i)$.}
On idempotent generated semigroups
Joo Araújo
Mathematics , 2011, DOI: 10.1007/s002330010089
Abstract: We provide short and direct proofs for some classical theorems proved by Howie, Levi and McFadden concerning idempotent generated semigroups of transformations on a finite set.
A emergência de estratégias transnacionais de ordenamento do território na Uni?o Europeia: reimaginar o espa?o europeu para criar novas formas de governan?a territorial?
EURE (Santiago) , 2004, DOI: 10.4067/S0250-71612004008900003
Abstract: territorial planning does not integrate european commission formal competences. but this has supported multiple favorable initiatives to the emergency of transnational development strategies of communitarian space. this apparent contradiction is analyzed from the reconstitution of the process that has permitted the european commission to hold today an effective role in this matter, in little more than ten years. the assumption of this paper is mainly based in informal processes of construction of a collective shared vision about europe?s future space. the text evaluates both meaning and possible implications of this evolution, defending the need of questioning supra-national strategies of territorial planning, as a way to participate in the political debate about the future of european and national projects
Rela??es entre mundo rural e mundo urbano: evolu??o histórica, situa??o actual e pistas para o futuro
EURE (Santiago) , 2000, DOI: 10.4067/S0250-71612000007800006
Abstract: este texto tem como finalidade identificar linhas de interven??o que favore?am o estabelecimento de rela??es de maior complementaridade e simbiose entre os mundos rural e urbano. com este objetivo presente, efectua-se, num primeiro ponto, uma reconstitui??o sintética das rela??es rural-urbano que historicamente dominaram nos países europeus, de forma a salientar as principais inflex?es ocorridas ao longo do tempo e seu significado. num segundo ponto sublinham-se os tra?os mais marcantes das situa??es hoje prevalecentes, interpretando-os à luz de breve reconstitui??o histórica anteriormente apresentada. por último, num terceiro ponto prop?em-se algumas linhas estratégicas de interven??o visando o establecer uma nova gera??o de rela??es de complementaridade entre o mundo rural e o mundo urbano
Red urbana, instrumento de equidad, cohesión y desarrollo
EURE (Santiago) , 1998, DOI: 10.4067/S0250-71611998007100005
Abstract: this document searches for a definition of strategic guidelines that transform the portuguese urban system into an efficient instrument for territorial equity, national cohesion and sustainable development. the text is made up of four parts. in the first part, the "return of the city" is acknowledged as an essential factor for the construction of the current cognitive society, making some considerations about geographical polarisation which inevitably is associated with this tendency. in the second part, the main modifications that recently have taken place in the morphology of the urban system are identified, underlining the threats and the opportunities created, in addition to the impact of those transformations which relate to the way one thinks one should act with regards to the urban systems. the third part registers the objectives that must be aimed for within a scope of transformation of urban systems understood as an instrument for development. finally, in the last part, the results of some recent studies on the portuguese urban system are summarised and, on the basis of the comparison of those results with the observations made in previous chapters, there are suggestions for the guidelines that should be taken into consideration if it is wished that the title of this text become reality
Rela??es entre mundo rural e mundo urbano: evolu??o histórica, situa??o actual e pistas para o futuro
Sociologia, Problemas e Práticas , 2000,
Abstract: as vis?es recentes sobre o mundo rural revelam grande permeabilidade à ideia de património como elemento estruturador de uma nova gera??o de estratégias e políticas de desenvolvimento para este tipo de territórios. neste texto adopta-se uma posi??o crítica face a esta tendência, organizada a partir de três preocupa??es: considerar a crescente indissociabilidade entre mundo rural e áreas urbanas; olhar para o futuro do mundo rural à luz das grandes linhas de evolu??o das rela??es campo-cidade observadas na europa; questionar a sustentabilidade generalizada de mundos rurais n?o agrícolas. apresentam-se, no final, diversas orienta??es estratégicas que poder?o contribuir para a defini??o de políticas e medidas que visem uma nova complementaridade rural-urbano, mais sensível aos ensinamentos da história, aos requisitos ambientais e às expectativas e necessidades das popula??es residentes em cada uma dessas áreas.

Copyright © 2008-2017 Open Access Library. All rights reserved.