809 research outputs found
National industry cluster templates and the structure of industry output dynamics: a stochastic geometry approach
Cluster analysis has been widely used in an Input-Output framework, with the main objective of uncover the structure of production, in order to better identify which sectors are strongly connected with each other and choose the key sectors of a national or regional economy. There are many empirical studies determining potential clusters from interindustry flows directly, or from their corresponding technical (demand) or market (supply) coefficients, most of them applying multivariate statistical techniques. In this paper, after identifying clusters this way, and since it may be expected that strongly (interindustry) connected sectors share a similar growth and development path, the structure of sectoral dynamics is uncovered, by means of a stochastic geometry technique based on the correlations of industry outputs in a given period of time. An application is made, using Portuguese input-output data, and the results do not clearly support this expectation.Clusters, Input-output analysis, Industry output dynamics
National industry cluster templates and the structure of industry output dynamics : a stochastic geometry approach
Cluster analysis has been widely used in an Input-Output framework, with the main objective of uncover the structure of production, in order to better identify
which sectors are strongly connected with each other and choose the key sectors of a
national or regional economy. There are many empirical studies determining potential
clusters from interindustry flows directly, or from their corresponding technical
(demand) or market (supply) coefficients, most of them applying multivariate statistical techniques. In this paper, after identifying clusters this way, and since it may be expected that strongly (interindustry) connected sectors share a similar growth and development path, the structure of sectoral dynamics is uncovered, by means of a stochastic geometry technique based on the correlations of industry outputs in a given period of time. An application is made, using Portuguese input-output data, and the results do not clearly
support this expectation
Counterexample Guided Inductive Optimization Applied to Mobile Robots Path Planning (Extended Version)
We describe and evaluate a novel optimization-based off-line path planning
algorithm for mobile robots based on the Counterexample-Guided Inductive
Optimization (CEGIO) technique. CEGIO iteratively employs counterexamples
generated from Boolean Satisfiability (SAT) and Satisfiability Modulo Theories
(SMT) solvers, in order to guide the optimization process and to ensure global
optimization. This paper marks the first application of CEGIO for planning
mobile robot path. In particular, CEGIO has been successfully applied to obtain
optimal two-dimensional paths for autonomous mobile robots using off-the-shelf
SAT and SMT solvers.Comment: 7 pages, 14rd Latin American Robotics Symposium (LARS'2017
Estudo das evidências de produção metalúrgica no Outeiro Redondo (Sesimbra)
O Outeiro Redondo (Sesimbra) é um sítio arqueológico importante da Estremadura Portuguesa, predominantemente ocupado durante o Calcolítico Pleno/Final (segunda metade do III Milénio a.C.). Este estudo foca‑se na caracterização elementar e microestrutural de 12 artefactos em liga de cobre e de um fragmento de cadinho provenientes deste sítio, contribuindo assim para o conhecimento da metalurgia primitiva naquela região.
A metodologia aplicada consistiu em espectrometria de fluorescência de raios ‑X dispersiva de energias, microscopia óptica, microscopia electrónica de varrimento com microanálise de raios ‑X e microdureza Vickers.
O arsénio está presente em todos os fragmentos metálicos, quer como impureza (2 wt%), os quais apresentam constituintes microestruturais característicos de diversos processos termomecânicos. O cadinho mostra evidências de uso em operações metalúrgicas de redução de minérios.The pre‑historic settlement of Outeiro Redondo located near Sesimbra is an important archaeological site of the Portuguese Estremadura region, predominantly occupied during the Full/Late Chalcolithic period (second half of the 3rd millennium B.C.). The present study focuses on the elemental and microstructural characterization of a group of 12 copper ‑based artefacts and a crucible fragment recovered from this settlement,
contributing to the understanding of the Chalcolithic metallurgy in this geographic area. The applied methodology
consisted of energy dispersive X ‑ray fluorescence spectrometry, optical microscopy, scanning electron microscopy with energy dispersive spectrometry and Vickers microhardness. Arsenic is present in all the metallic fragments, – whether as impurity (2 wt%) – which exhibit microstructural features characteristic of several thermomechanical processes. The crucible shows evidence of use in metallurgical operations, namely smelting.Patrocinador oficial - Fundação Millennium BCP. Apoio institucional - Biblioteca Nacional de Portugal e Parques de Sintra- Monte da Lua. O Projecto Metalurgia Primitiva no Território Português – EarlyMetal (PTDC/HIS ‑ARQ/110442/2008) financiado pela Fundação para a Ciência e Tecnologia (FCT)
Seismic assessment of St. James church by means of pushover analysis : before and after the New Zealand earthquake
The paper presents a numerical study for the seismic assessment of the St James Church in Christchurch,
New Zealand affected by the recent 2011 earthquake and subsequent aftershocks. The structural
behaviour of the Church has been evaluated using the finite element modelling technique, in which the
nonlinear behaviour of masonry has been taken into account by proper constitutive assumptions. Two
numerical models were constructed, one incorporating the existing structural damage and the other
considering the intact structure. The validation of the numerical models was achieved by the calibration
of the damaged model according to dynamic identification tests carried out in situ after the earthquake.
Non-linear pushover analyses were carried out on both principal directions demonstrating that, as a result
of the seismic action, the Church can no longer be considered safe. Pushover analysis results of the
undamaged model show reasonable agreement with the visual inspection performed in situ, which further
validates the model used. Finally, limit analysis using macro-block analysis was also carried out to
validate the main local collapse mechanisms of the Church.(undefined
Post-earthquake numerical assessment and reinforcement of St James Church, New Zealand
This paper presents a numerical study on the seismic assessment and reinforcement of St James Church, affected
by the 2011 New Zealand Earthquake. Numerical analyses were performed using a finite element model
including the structural damage of the Church. The numerical model was calibrated against experimental results
obtained from the dynamic identification tests carried out in situ. Nonlinear pushover analyses were performed
in order to understand the structural behaviour of the damaged Church. The analysis of the results suggests that
the damaged structure is not safe according to the new national specifications. Therefore, some reinforcement
measures are needed to improve the seismic behaviour of the structure. A reinforcement solution is proposed
taking into account the historical heritage value of the building, trying to maintain as much as possible the
original aspect of the Church. Pushover analyses were also performed in the reinforced numerical model,
proving its effectiveness
Post-earthquake seismic analysis of St James church, New Zealand
The paper presents a numerical study of the seismic assessment of the St James
Church in Christchurch, New Zealand affected by the most recent 2011 earthquake and
subsequent aftershocks. Dynamic identification tests, as well as a careful visual inspection,
were performed in the Church in order to understand its structural behaviour after the
seismic action. The seismic assessment of the Church has been done using the finite
element modelling technique, in which the nonlinear behaviour of masonry has been taken
into account by proper constitutive assumptions. A model updating according to the
experimental results was carried out in order to validate the numerical model, which
includes the simulation of the damage identified in the structure. Nonlinear pushover
analyses were carried out demonstrating that, as a result of the seismic action, the Church
can no longer be considered safe.
Another numerical model was analysed, this time considering the intact structure. The
pushover analysis results of this undamaged model show good agreement with the visual
inspection performed in situ, which further validates the model used.
Moreover, since the analysis proved that the structure is no longer safe, a reinforcement
strategy is proposed and analysed, proving its effectiveness.(undefined
Smelting and recycling evidences from the Late Bronze Age habitat site of Baiões (Viseu, Portugal)
Many aspects of bronze production during Late Bronze Age in Western Europe are so far unknown. In the present study selected artefact fragments and metallurgical debris, which include a slag fragment, from
the emblematic Late Bronze Age habitat site of Castro da Senhora da Guia de Baio˜es (Viseu, Portugal) have been studied by optical microscopy, micro-EDXRF, SEM–EDS and XRD. Evidences were found for bronze production involving smelting and recycling. Compositional analysis showed that the artefacts are made of a bronze with 133 wt.% Sn (average and one standard deviation) and a low impurity pattern, namely <0.1 wt.% Pb, being comparable with the composition of other bronzes from the same
region (the Central Portuguese Beiras). This alloy is generally different from elsewhere Atlantic and Mediterranean bronzes, which show frequently slightly lower Sn contents and higher impurity patterns,namely Pb which is often present as an alloying element. The present study gives further support to early
proposals suggesting the exploration of the Western Iberian tin resources during Late Bronze Age, and besides that, it indicates that metalworking and smelting could have been a commonplace activity requiring no specific facilities, being bronze produced at a domestic scale in this Western extreme of
Europe
Identification of ancient gilding technology and Late Bronze Age metallurgy by EDXRF, Micro-EDXRF, SEM-EDS and metallographic techniques
A combination of analytical techniques capable of elemental and microstructural characterisation was used for the identification of ancient gilding technology and
bronze metallurgy. EDXRF, micro-EDXRF, SEM-EDS analysis and metallographic examinations were applied in the study of artefacts dating to the end of the second millennium BC from Crasto de São Romão in Central Portugal. Results report to the finding of an exceptional
gilded copper nail among bronze artefacts with 9 wt.% to15 wt.% tin and minute other metallic impurities. Additionally, analysis of a crucible fragment points out for bronze production at the archaeological site. EDXRF
and micro-EDXRF analysis made on the copper nail showed that it was gilded only on the front side of the head, and that the gold layer has been lost in the most exposed areas. SEM-EDS analysis showed that the gold
layer has 5–8 μm in thickness and is covered with a thick
corrosion layer. The gilding technique is discussed based on the gold layer composition and gold/copper substrate interface. So far, this object seems to be the first diffusion
gilded artefact identified in the Portuguese territory dated to Late Bronze Age
Compositional and microstructural characterization of grave goods from Anta do Malhão and Soalheironas: an insight into the diachronic use of arsenical copper from the 3rd to the 2nd Millennium BC
info:eu-repo/semantics/publishedVersio
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