8,278 research outputs found
On Logical Depth and the Running Time of Shortest Programs
The logical depth with significance of a finite binary string is the
shortest running time of a binary program for that can be compressed by at
most bits. There is another definition of logical depth. We give two
theorems about the quantitative relation between these versions: the first
theorem concerns a variation of a known fact with a new proof, the second
theorem and its proof are new. We select the above version of logical depth and
show the following. There is an infinite sequence of strings of increasing
length such that for each there is a such that the logical depth of the
th string as a function of is incomputable (it rises faster than any
computable function) but with replaced by the resuling function is
computable. Hence the maximal gap between the logical depths resulting from
incrementing appropriate 's by 1 rises faster than any computable function.
All functions mentioned are upper bounded by the Busy Beaver function. Since
for every string its logical depth is nonincreasing in , the minimal
computation time of the shortest programs for the sequence of strings as a
function of rises faster than any computable function but not so fast as
the Busy Beaver function.Comment: 12 pages LaTex (this supercedes arXiv:1301.4451
Absence of Gluonic Components in Axial and Tensor Mesons
A quarkonium-gluonium mixing scheme previously developed to describe the
characteristic of the pseudoscalar mesons is applied to axial and tensor
mesons. The parameters of the model are determined by fitting the eigenvalues
of a mass matrix. The corresponding eigenvectors give the proportion of light
quarks, strange quarks and glueball in each meson. However the predictions of
the model for branching ratios and electromagnetic decays are incompatible with
the experimental results. These results suggest the absence of gluonic
components in the states of axial and tensor isosinglet mesons analyzed here.Comment: 12 page
Thermoelectric response of FeTeSe: evidence for strong correlation and low carrier density
We present a study of the Seebeck and Nernst coefficients of
FeTeSe extended up to 28 T. The large magnitude of the
Seebeck coefficient in the optimally doped sample tracks a remarkably low
normalized Fermi temperature, which, like other correlated superconductors, is
only one order of magnitude larger than T. We combine our data with other
experimentally measured coefficients of the system to extract a set of
self-consistent parameters, which identify FeTeSe as a
low-density correlated superconductor barely in the clean limit. The system is
subject to strong superconducting fluctuations with a sizeable vortex Nernst
signal in a wide temperature window.Comment: 4 pages including 4 figure
Elastic properties of carbon nanotubes and their heterojunctions
Comprehensive studies on the modelling and numerical simulation of the mechanical behaviour under tension, bending and torsion of single-walled carbon nanotubes and their heterojunctions are performed. It is proposed to deduce the mechanical properties of the carbon nanotubes heterojunctions from the knowledge of the mechanical properties of the single-walled carbon nanotubes, which are their constituent key unit
Experimental characterization of the flexural behaviour of steel fibre reinforced concrete according to RILEM TC 162-TDF recommendations
The post-cracking energy absorption capacity is the concrete property most benefited by
steel fibre reinforcement, usually designated by toughness. Different test set-ups, test
procedures and parameters have been proposed to evaluate the toughness of the steel
fibre reinforced concrete (SFRC), but none of them has received a general acceptation by
scientific and technical communities. As a consequence, designers put some reserves on
the use of SFRC, because they are not confident on the design practice to be adopted,
resulting in the exclusion of SFRC in applications where it could be the most suitable
solution. In the last years RILEM TC 162 – TDF has published documents where
recommendations for characterizing and designing SFRC structures are proposed. A
general acceptation of these recommendations can be only taken if they are deeply
analysed and checked by a large number of research centres.
This work intends to give some contribution for this analysis. It has also the purpose of
evaluating the influence of the fibre content, percentage of cement replaced by fly ash
and SFRC age on the post-cracking behaviour of the SFRC, under the experimental
framework recommended by RILEM TC 162 – TDF.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/34793/99. "Cost competitive steel fibre reinforced concrete for industrial pavements“Pisonort – Pavimentos industriais LdaSeci
Joints in pavements of industrial buildings
Os pavimentos de edifÃcios industriais são das obras de engenharia civil em que
ocorrem maior número de patologias. Tal deve-se a deficiente empenho dos intervenientes na
concepção, projecto e construção deste tipo de estruturas, muitas vezes associado ao
sentimento de que a não verificação dos estados limites de utilização e últimos não está
directamente ligado à ocorrência de acidentes trágicos. Porém, é reconhecido que, em muitos
casos, o deficiente funcionamento deste tipo de estruturas conduz a prejuÃzos económicos
significativos e, por vezes, a acidentes envolvendo seres humanos.
De entre as patologias ocorridas em pavimentos industriais, as devidas directa ou
indirectamente com juntas, são as mais correntes. Um deficiente traçado de juntas pode
conduzir, em caso limite, à inutilização do pavimento, sendo a reabilitação deste bastante
onerosa.
Este trabalho é dedicado à temática das juntas em pavimentos de edifÃcios industriais, desde
a sua concepção, traçado até ao dimensionamento de elementos de transferência de carga
entre painéis adjacentes à junta.Pavements of industrial floors are one of the Civil Engineering realizations where
higher number of pathologies occurred. This is caused by the deficient attitude of the
intervenients in the conception, design, execution and quality control of this type of structural
application. This behavior is related to the idea that a tragic accident will not occur even if
the serviceability and ultimate limit analysis are not accomplished in the design practice. In
several cases, however, a pavement with deficient operation leads to significant economical
loses, and, sometimes to human injuries
Reforço de pavimentos de edifÃcios industriais com laminados de fibras de carbono
A eficácia da técnica de reforço constituÃda pela fixação de laminados de CFRP, com adesivo epoxy, no betão de recobrimento de elementos de betão armado tem sido comprovada nos últimos anos no reforço à flexão de vigas e pilares, e no reforço ao corte de vigas. No presente trabalho, esta técnica é aplicada no reforço à flexão de painéis de um pavimento de um edifÃcio
industrial. Os procedimentos e o cálculo do reforço são descritos no presente trabalho.Pisonort Lda (pavimentos industriais)
A new method based on noise counting to monitor the frontend electronics of the LHCb muon detector
A new method has been developed to check the correct behaviour of the
frontend electronics of the LHCb muon detector. This method is based on the
measurement of the electronic noise rate at different thresholds of the
frontend discriminator. The method was used to choose the optimal discriminator
thresholds. A procedure based on this method was implemented in the detector
control system and allowed the detection of a small percentage of frontend
channels which had deteriorated. A Monte Carlo simulation has been performed to
check the validity of the method
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