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Search Results: 1 - 10 of 18903 matches for " Paulo; "
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Influence of Coolant in Machinability of Titanium Alloy (Ti-6Al-4V)  [PDF]
Muthukrishnan Namb, Davim Paulo
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2011, DOI: 10.4236/jsemat.2011.11002
Abstract: Application of titanium alloy has increased many fields since the past 50 years. The major drawback encountered during machining was difficult to cut and the formation of BUE (Built up Edge). This paper presents the tool wear study of TTI 15 ceramic insert (80% Aluminum oxide and 20 % Titanium carbide) on machining Ti-6Al-4V at moderate speed with and without the application of water soluble servo cut S coolant. Titanium alloy is highly refractory metal and machining titanium is challenging to the manufacturers. Experiments were carried out on medium duty lathe. Application of coolant tends to reduce toolwear and minimize adhesion of the work material on the cutting tool during machining and also improves the surface finish. Result provides some useful information.
Warming Power of CO2 and H2O: Correlations with Temperature Changes  [PDF]
Paulo Cesar Soares
International Journal of Geosciences (IJG) , 2010, DOI: 10.4236/ijg.2010.13014
Abstract: The dramatic and threatening environmental changes announced for the next decades are the result of models whose main drive factor of climatic changes is the increasing carbon dioxide in the atmosphere. Although taken as a premise, the hypothesis does not have verifiable consistence. The comparison of temperature changes and CO2 changes in the atmosphere is made for a large diversity of conditions, with the same data used to model climate changes. Correlation of historical series of data is the main approach. CO2 changes are closely related to temperature. Warmer seasons or triennial phases are followed by an atmosphere that is rich in CO2, reflecting the gas solving or exsolving from water, and not photosynthesis activity. Interannual correlations between the variables are good. A weak dominance of temperature changes precedence, relative to CO2 changes, indicate that the main effect is the CO2 increase in the atmosphere due to temperature rising. Decreasing temperature is not followed by CO2 decrease, which indicates a different route for the CO2 capture by the oceans, not by gas re-absorption. Monthly changes have no correspondence as would be expected if the warming was an important absorption-radiation effect of the CO2 increase. The anthropogenic wasting of fossil fuel CO2 to the atmosphere shows no relation with the temperature changes even in an annual basis. The absence of immediate relation between CO2 and temperature is evidence that rising its mix ratio in the atmosphere will not imply more absorption and time residence of energy over the Earth surface. This is explained because band absorption is nearly all done with historic CO2 values. Unlike CO2, water vapor in the atmosphere is rising in tune with temperature changes, even in a monthly scale. The rising energy absorption of vapor is reducing the outcoming long wave radiation window and amplifying warming regionally and in a different way around the globe.
Leverage and the Maturity Structure of Debt in Emerging Markets  [PDF]
Cesario Mateus, Paulo Terra
Journal of Mathematical Finance (JMF) , 2013, DOI: 10.4236/jmf.2013.33A005
Abstract:

The aim of this paper is to analyse for a multi-country large emerging market sample the choice between debt and equity simultaneously with the decision between short- and long-term debts. In order to investigate the joint decision among leverage and maturity, we examine an unique sample of 986 firms and 13,490 firm-year observations from Latin America and 686 firms and 7919 firm-year observations from Eastern Europe for the period 1990-2003. We employ dynamic panel data analysis using Generalized Method of moments. The empirical results support three main findings. First, the cross-effects between leverage and maturity behave exactly the opposite between Latin America and Eastern Europe sub-samples. Capital structure and debt maturity are policy complements in Latin America and substitutes in Eastern Europe. Second, there is a significant dynamic effects component in the determination of leverage and maturity. Finally, adjustment to the target, maturity is by no means costless and instantaneous with firm’s facing moderate adjustment costs.

Youth and Social Security Coverage in Brazil  [PDF]
Paulo Tafner, Carolina Botelho
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.21014
Abstract: Brazil is still a young country, just starting the process of aging, but Brazils spending on social security is similar to those countries whose population aging has already occurred. Some studies explain the high cost of the Brazilian Social Security System due to the assumption that there is a positive relationship between social security and poverty alleviation. In fact, the effectiveness of this instrument as reducing poverty was high until 2002, but stopped growing and fell slightly thereafter. Brazilian law provides that wives and children or stepchildren under age 21, or under 25, since they are college students, are welfare beneficiaries. In other words they are protected by Brazilian Social Security System. However, data reveals that in Brazil, children and young people have a very low social security direct coverage, which increases with age and reaches high levels for individuals aged 60 or older. Children and young people are the groups most affected by poverty and extreme poverty in Brazil. In this sense, the assumption according to which Social Security helps combat family poverty is flawed. Considering these issues, this article aims to contribute to the debate on the need to rethink the Brazilian Social Security System and the need of construction of specific policies for children and young people in Brazil.
Trends of Development of International Water Law  [PDF]
Paulo Canelas de Castro
Beijing Law Review (BLR) , 2015, DOI: 10.4236/blr.2015.64025
Abstract: International water law has been witnessing profound changes in the latter twenty years. These changes denote certain cardinal options for new goals and values that the newer international water law is seeking to embrace. Amongst these new goals and values, the ones of environmentalization, humanisation, economicisation stand out as attempts at bringing efficient response to the challenges set by the current global water crisis and the more complex expectations of the international community. They amount to an innovative normative message and even true paradigm-shifts in the understanding of international water law. These trends of development of international water law set this legal field in line with other chapters of contemporary international law and derive in part from the cross-fertilisation of normative ideas and principles between these chapters of international law.
Leitura de Salazar vai ao cinema II - A 'Política do Espírito' no Jornal Português, de Maria do Carmo Pi arra
Paulo Cunha,Paulo Cunha
Doc On-Line : Revista Digital de Cinema Documentário , 2011,
Abstract:
Dust-filled axially symmetric universes with a cosmological constant
Paulo Aguiar,Paulo Crawford
Physics , 2000, DOI: 10.1103/PhysRevD.62.123511
Abstract: Following the recent recognition of a positive value for the vacuum energy density and the realization that a simple Kantowski-Sachs model might fit the classical tests of cosmology, we study the qualitative behavior of three anisotropic and homogeneous models: Kantowski-Sachs, Bianchi type-I and Bianchi type-III universes, with dust and a cosmological constant, in order to find out which are physically permitted. We find that these models undergo isotropization up to the point that the observations will not be able to distinguish between them and the standard model, except for the Kantowski-Sachs model $(\Omega_{k_{0}}<0)$ and for the Bianchi type-III $(\Omega_{k_{0}}>0)$ with $\Omega_{\Lambda_{0}}$ smaller than some critical value $\Omega_{\Lambda_{M}}$. Even if one imposes that the Universe should be nearly isotropic since the last scattering epoch ($z\approx 1000$), meaning that the Universe should have approximately the same Hubble parameter in all directions (considering the COBE 4-Year data), there is still a large range for the matter density parameter compatible with Kantowsky-Sachs and Bianchi type-III if $|\Omega_0+\Omega_{\Lambda_0}-1|\leq \delta$, for a very small $\delta$ . The Bianchi type-I model becomes exactly isotropic owing to our restrictions and we have $\Omega_0+\Omega_{\Lambda_0}=1$ in this case. Of course, all these models approach locally an exponential expanding state provided the cosmological constant $\Omega_\Lambda>\Omega_{\Lambda_{M}}$.
Sachs-Wolfe effect in some anisotropic models
Paulo Aguiar,Paulo Crawford
Physics , 2001,
Abstract: In this work it is shown for some spatially homogeneous but anisotropic models how the inhomogeneities in the distribution of matter on the surface of the last scattering produce anisotropies in large angular scales (larger than $\vartheta \gtrsim 2^\circ$) which do not differ from the ones produced in Friedmann-Lema\^itre-Robertson-Walker (FLRW) geometries. That is, for these anisotropic models, the imprint left on the cosmic microwave background radiation (CMBR) by the primordial density fluctuations, in the form of a fractional variation of the temperature of this radiation, is governed by the same expression as the one given for FLRW models. More precisely, under adiabatic initial conditions, the classical Sachs-Wolfe effect is recovered, provided the anisotropy of the overall expansion is small. This conclusion is in agreement with previous work on the same anisotropic models where we found that they may go through an `isotropization' process up to the point that the observations are unable to distinguish them from the standard FLRW model, if the Hubble parameters along the orthogonal directions are assumed to be approximately equal at the present epoch. Here we assumed upper bounds on the present values of anisotropic parameters imposed by COBE observations.
Axially Symmetric Cosmological Models with Perfect Fluid and Cosmological Constant
Paulo Aguiar,Paulo Crawford
Physics , 1998, DOI: 10.1023/A:1002071910713
Abstract: Following recent considerations of a non-zero value for the vacuum energy density and the realization that a simple Kantowski-Sachs model might fit the classical tests of cosmology, we study the qualitative behavior of three anisotropic and homogeneous models: Kantowski-Sachs, Bianchi I and Bianchi III universes, with dust and cosmological constant, in order to find out which are physically permitted. In fact, these models undergo isotropisation, except for the Kantowski-Sachs model (Omega_{k_{0}}>0) with Omega_{Lambda_{0}}< Omega_{Lambda_{M}} and for the Bianchi III (Omega_{k_{0}}<0) with Omega_{Lambda_{0}}
Large Social Networks can be Targeted for Viral Marketing with Small Seed Sets
Paulo Shakarian,Damon Paulo
Computer Science , 2012,
Abstract: In a "tipping" model, each node in a social network, representing an individual, adopts a behavior if a certain number of his incoming neighbors previously held that property. A key problem for viral marketers is to determine an initial "seed" set in a network such that if given a property then the entire network adopts the behavior. Here we introduce a method for quickly finding seed sets that scales to very large networks. Our approach finds a set of nodes that guarantees spreading to the entire network under the tipping model. After experimentally evaluating 31 real-world networks, we found that our approach often finds such sets that are several orders of magnitude smaller than the population size. Our approach also scales well - on a Friendster social network consisting of 5.6 million nodes and 28 million edges we found a seed sets in under 3.6 hours. We also find that highly clustered local neighborhoods and dense network-wide community structure together suppress the ability of a trend to spread under the tipping model.
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