42,746 research outputs found
Asserting the Portuguese Civil Engineering Identity: the Role Played by the Ăcole des ponts et chaussĂ©es
This paper focuses on the Portuguese engineers who returned to Portugal following a training period at Ăcole des Ponts et ChaussĂ©es, in Paris between 1831 and 1870.
During the 19th century, in spite of the creation of engineering schools, such as the Military Academy (1836), the Polytechnic School of Lisbon (1837), the Polytechnic Academy of Oporto (1837), the number of engineers to ensure the planning and the direction of the public works remained insufficient. Moreover, the education provided by these schools granted almost no room for fieldwork. Like in the other European States, some Portuguese engineers tried to complete their training in foreign countries, in particular by attending schools such as the Ăcole des Ponts et ChaussĂ©es de Paris.
The studies which they carried out as well as the projects and the âmissions dâĂ©tudesâ enabled them to intervene in various areas, from the construction of bridges and railways to agricultural hydraulics on their return to Portugal. Following their return, these engineers played an important role both in the transfer of knowledge as well as in updating Portuguese engineering. They designed and directed various public works and transmitted to their subordinates the most modern methods of planning and construction of roads, railways and seaports. In addition, they were appointed to political and administrative positions in particular within the MinistĂ©rio das Obras PĂșblicas, ComĂ©rcio e IndĂșstria created in 1852, in the context of which they had to evaluate, authorize or reject various engineering projects. Finally, some were appointed professors in Portuguese engineering schools where they taught new theories, methods and practices of civil engineering which they had learnt in Paris or during trips abroad
âLandscape and Heritage of Hydroelectricity in Portugalâ
Hydroelectric power plants provided countries with scarcity of coal, such as Portugal, with a vital source of energy for the production of electricity in large quantities. Therefore, since the late 19th century the use of waterfalls as producers of electric power was a topic of study and interest among engineers and the matter was regularly discussed at the Association of Portuguese Civilian Engineers.
The great hydroelectric power plants, considered by many as the cathedrals of the second industrial revolution are an important industrial heritage which is important to value and appreciate. Hydroelectricity also gave origin to new landscapes and the problem today regards the management of this new landscape and the construction of new patrimonial values
First study of the three-gluon static potential in Lattice QCD
We estimate the potential energy for a system of three static gluons in
Lattice QCD. This is relevant for the different models of three-body glueballs
have been proposed in the literature, either for gluons with a constituent
mass, or for massless ones. A Wilson loop adequate to the static hybrid
three-body system is developed. We study different spacial geometries, to
compare the starfish model with the triangle model, for the three-gluon
potential. We also study two different colour structures, symmetric and
antisymmetric, and compare the respective static potentials. A first simulation
is performed in a periodic Lattice, with and fm.Comment: 8 pages, 10 figure
On the Dirac equation with PT-symmetric potentials in the presence of position-dependent mass
The relativistic problem of fermions subject to a PT-symmetric potential in
the presence of position-dependent mass is reinvestigated. The influence of the
PT-symmetric potential in the continuity equation and in the orthonormalization
condition are analyzed. In addition, a misconception diffused in the literature
on the interaction of neutral fermions is clarified.Comment: 8 page
Perturbative gravitational couplings and Siegel modular forms in string models
We consider four-parameter string models with Hodge numbers
and , and we express their perturbative Wilsonian
gravitational coupling in terms of Siegel modular forms.Comment: 8 pages, Latex 2.09, Contribution to the Proceedings of the 30th
International Symposium Ahrenshoop on the Theory of Elementary Particles,
Buckow, August 27-31, 199
Perturbative and non-perturbative monodromies in N=2 heterotic string vacua
In this talk we summarise our recent results on perturbative and
non-perturbative monodromies in four-dimensional heterotic strings with
space-time supersymmetry, and we compare our results with the rigid
Yang-Mills monodromies.Comment: 6 pages, latex using espcrc2. Based on Talks given at the 29th
International Symposium on the Theory of Elementary Particles, Buckow, August
1995 and at the 5th Hellenic School and Workshop on Elementary Particle
Physics, Corfu, September 199
Higher-Order Gravitational Couplings and Modular Forms in Heterotic String Compactifications
The restrictions of target--space duality are imposed at the perturbative
level on the holomorphic Wilsonian couplings that encode certain higher-order
gravitational interactions in heterotic string compactifications. A
crucial role is played by non-holomorphic corrections. The requirement of
symplectic covariance and an associated symplectic anomaly equation play an
important role in determining their form. For models which also admit a type-II
description, this equation coincides with the holomorphic anomaly equation for
type-II compactifications in the limit that a specific K\"ahler-class modulus
grows large. We explicitly evaluate some of the higher-order couplings for a
toroidal compactification with two moduli and , and we express them in
terms of modular forms.Comment: 39 pages, Late
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