45,063 research outputs found
On the Evaluation of the Mechanical Behaviour of Structural Glass Elements
Glass can be considered to be a high-technology engineering material with a
multifunctional potential for structural applications. However, the conventional approach to the use
of glass is often based only on its properties of transparency and isolation. It is thus highly
appropriate and necessary to study the mechanical behaviour of this material and to develop
adequate methods and models leading to its characterisation. It is evident that the great potential of
growth for structural glass applications is an important opportunity of development for the glass
industry and the building/construction sectors. The work presented in this paper is a reflection of
this conclusion. The authors shortly present the state-of-the-art on the application of glass as a
structural element in building and construction, and refer to other potential fields of application and
available glass materials. The experimental procedures and methods adopted in three-point bending
tests performed on 500 × 100 [mm2] float, laminated and tempered glass specimens with
thicknesses between 4 and 19 mm are thoroughly described. The authors evaluated the mechanical
strength and stiffness of glass for structural applications. This work contributes to a deeper
knowledge of the properties of this material
Using full-scale duckweed ponds as the finish stage for swine waste treatment with a focus on organic matter degradation
Artigo Publicado em: IWA - Water Science & TechnologyThe rapid increase in the number of swine has caused pronounced environmental impacts worldwide, especially on water resources. As an aggregate, smallholdings have an important role in South American pork production, contributing to the net diffusion of pollution. Thus, duckweed ponds have been successfully used for swine waste polishing, mainly for nutrient removal. Few studies have been carried out to assess organic matter degradation in duckweed ponds. Hence, the present study evaluated the efficiency of two full-scale duckweed ponds for organic matter reduction of swine waste on small pig farms. Duckweed ponds, in series, received the effluent after an anaerobic biodigester and storage pond, with a flow rate of 1 m3 day 1. After 1 year of monitoring, an improvement in effluent quality was observed, with a reduction in biochemical oxygen demand (BOD) and total chemical oxygen demand (tCOD), respectively, of 94.8 and 96.7%, operating at a loading rate of approximately 27 kgBOD ha 1 day 1 and 131 kgCOD ha 1 day 1. Algae inhibition due to duckweed coverage was strongly observed in the pond effluent, where chlorophyll a and turbidity remained below 25 μg L 1 and 10 NTU. Using the study conditions described herein, duckweed ponds were shown to be a suitable technology for swine waste treatment, contributing to the environmental sustainability of rural areas
Perturbative and non-perturbative renormalization results of the Chromomagnetic Operator on the Lattice
The Chromomagnetic operator (CMO) mixes with a large number of operators
under renormalization. We identify which operators can mix with the CMO, at the
quantum level. Even in dimensional regularization (DR), which has the simplest
mixing pattern, the CMO mixes with a total of 9 other operators, forming a
basis of dimension-five, Lorentz scalar operators with the same flavor content
as the CMO. Among them, there are also gauge noninvariant operators; these are
BRST invariant and vanish by the equations of motion, as required by
renormalization theory. On the other hand using a lattice regularization
further operators with will mix; choosing the lattice action in a
manner as to preserve certain discrete symmetries, a minimul set of 3
additional operators (all with ) will appear. In order to compute all
relevant mixing coefficients, we calculate the quark-antiquark (2-pt) and the
quark-antiquark-gluon (3-pt) Green's functions of the CMO at nonzero quark
masses. These calculations were performed in the continuum (dimensional
regularization) and on the lattice using the maximally twisted mass fermion
action and the Symanzik improved gluon action. In parallel, non-perturbative
measurements of the matrix element are being performed in simulations
with 4 dynamical () twisted mass fermions and the Iwasaki improved
gluon action.Comment: 7 pages, 1 figure, 3 tables, LATTICE2014 proceeding
matrix elements of the chromomagnetic operator on the lattice
We present the results of the first lattice QCD calculation of the matrix elements of the chromomagnetic operator , which appears in the effective Hamiltonian
describing transitions in and beyond the Standard Model. Having
dimension 5, the chromomagnetic operator is characterized by a rich pattern of
mixing with operators of equal and lower dimensionality. The multiplicative
renormalization factor as well as the mixing coefficients with the operators of
equal dimension have been computed at one loop in perturbation theory. The
power divergent coefficients controlling the mixing with operators of lower
dimension have been determined non-perturbatively, by imposing suitable
subtraction conditions. The numerical simulations have been carried out using
the gauge field configurations produced by the European Twisted Mass
Collaboration with dynamical quarks at three values of the
lattice spacing. Our result for the B-parameter of the chromomagnetic operator
at the physical pion and kaon point is , while
in the SU(3) chiral limit we obtain . Our findings are
significantly smaller than the model-dependent estimate ,
currently used in phenomenological analyses, and improve the uncertainty on
this important phenomenological quantity.Comment: 20 pages, 4 figures, 2 table. Refined SU(3) ChPT analysis with no
changes in the final result. Version to appear in PR
The chromomagnetic operator on the lattice
We study matrix elements of the "chromomagnetic" operator on the lattice.
This operator is contained in the strangeness-changing effective Hamiltonian
which describes electroweak effects in the Standard Model and beyond.
Having dimension 5, the chromomagnetic operator is characterized by a rich
pattern of mixing with other operators of equal and lower dimensionality,
including also non gauge invariant quantities; it is thus quite a challenge to
extract from lattice simulations a clear signal for the hadronic matrix
elements of this operator.
We compute all relevant mixing coefficients to one loop in lattice
perturbation theory; this necessitates calculating both 2-point
(quark-antiquark) and 3-point (gluon-quark-antiquark) Green's functions at
nonzero quark masses. We use the twisted mass lattice formulation, with
Symanzik improved gluon action.
For a comprehensive presentation of our results, along with detailed
explanations and a more complete list of references, we refer to our
forthcoming publication [1].Comment: 7 pages, 1 figure. Talk presented at the 31st International Symposium
on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013, Mainz,
German
Some integrals ocurring in a topology change problem
In a paper presented a few years ago, De Lorenci et al. showed, in the
context of canonical quantum cosmology, a model which allowed space topology
changes (Phys. Rev. D 56, 3329 (1997)). The purpose of this present work is to
go a step further in that model, by performing some calculations only estimated
there for several compact manifolds of constant negative curvature, such as the
Weeks and Thurston spaces and the icosahedral hyperbolic space (Best space).Comment: RevTeX article, 4 pages, 1 figur
Seismic vulnerability of churches in Faial and Pico islands, Azores
Earthquakes represent one of the main cause of serious damage and loss of historic and architectural heritage. Interventions to preserve these building should start with a careful knowledge and assessment of their seismic vulnerability, in order to support any needed retrofitting and strengthening measures.
This paper proposes a procedure to register and diagnose of the level of damage on churches after the occurrence of an earthquake, and also to assess the seismic vulnerability of this type of construction. This procedure was applied to sixteen churches in the Azores islands which were hit by the July 9th 1998 earthquake.
Belfries of church towers are elements with a particular seismic vulnerability. For this reason, and based on the Italian methodology proposed by the Linee Guida (2006), it is applied to belfries of two churches from Pico (Azores), a simplified mechanical model for assessment of seismic vulnerability of this type of structures
Carbon coating of the SPS dipole chambers
The Electron Multipacting (EM) phenomenon is a limiting factor for the
achievement of high luminosity in accelerators for positively charged particles
and for the performance of RF devices. At CERN, the Super Proton Synchrotron
(SPS) must be upgraded in order to feed the Large Hadron Collider (LHC) with 25
ns bunch spaced beams. At such small bunch spacing, EM may limit the
performance of the SPS and consequently that of the LHC. To mitigate this
phenomenon CERN is developing a carbon thin film coating with low Secondary
Electron Yield (SEY) to coat the internal walls of the SPS dipoles beam pipes.
This paper presents the progresses in the coating technology, the performance
of the carbon coatings and the strategy for a large scale production.Comment: 7 pages, contribution to the Joint INFN-CERN-EuCARD-AccNet Workshop
on Electron-Cloud Effects: ECLOUD'12; 5-9 Jun 2012, La Biodola, Isola d'Elba,
Italy; CERN Yellow Report CERN-2013-002, pp.141-14
Avaliação da inclusão da levedura (Saccharomyces cerevisiae) como suplemento, em dietas para juvenis de tambaqui (Colossoma macropomum).
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