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

G\"odel-type Spacetimes in Induced Matter Gravity Theory

A five-dimensional (5D) generalized G\"odel-type manifolds are examined in the light of the equivalence problem techniques, as formulated by Cartan. The necessary and sufficient conditions for local homogeneity of these 5D manifolds are derived. The local equivalence of these homogeneous Riemannian manifolds is studied. It is found that they are characterized by three essential parameters $k$, $m^2$ and $\omega$: identical triads $(k, m^2, \omega)$ correspond to locally equivalent 5D manifolds. An irreducible set of isometrically nonequivalent 5D locally homogeneous Riemannian generalized G\"odel-type metrics are exhibited. A classification of these manifolds based on the essential parameters is presented, and the Killing vector fields as well as the corresponding Lie algebra of each class are determined. It is shown that the generalized G\"odel-type 5D manifolds admit maximal group of isometry $G_r$ with $r=7$, $r=9$ or $r=15$ depending on the essential parameters $k$, $m^2$ and $\omega$. The breakdown of causality in all these classes of homogeneous G\"odel-type manifolds are also examined. It is found that in three out of the six irreducible classes the causality can be violated. The unique generalized G\"odel-type solution of the induced matter (IM) field equations is found. The question as to whether the induced matter version of general relativity is an effective therapy for these type of causal anomalies of general relativity is also discussed in connection with a recent article by Romero, Tavakol and Zalaletdinov.Comment: 19 pages, Latex, no figures. To Appear in J.Math.Phys.(1999

Tuned liquid dampers simulation for earthquake response control of buildings

This paper is focused on the study of an earthquake protection system, the Tuned Liquid Damper (TLD), which can, if adequately designed, reduce earthquake demands on buildings. This positive effect is accomplished taking into account the oscillation of the free surface of a fluid inside a tank (sloshing). The behaviour of an isolated Tuned Liquid Damper, subjected to a sinusoidal excitation at its base, with different displacement amplitudes, was studied by finite element analysis. The efficiency of the TLD in improving the seismic response of an existing building, representative of modern architecture buildings in southern European countries was also evaluated based on linear dynamic analyses

Injection locking of a low cost high power laser diode at 461 nm

Stable laser sources at 461 nm are important for optical cooling of strontium atoms. In most existing experiments this wavelength is obtained by frequency doubling infrared lasers, since blue laser diodes either have low power or large emission bandwidths. Here, we show that injecting less than 10 mW of monomode laser radiation into a blue multimode 500 mW high power laser diode is capable of slaving at least 50% of the power to the desired frequency. We verify the emission bandwidth reduction by saturation spectroscopy on a strontium gas cell and by direct beating of the slave with the master laser. We also demonstrate that the laser can efficiently be used within the Zeeman slower for optical cooling of a strontium atomic beam.Comment: 2nd corrected version (minor revisions); Manuscript accepted for publication in Review of Scientific Instruments; 5 pages, 6 figure

Risk-based Security Measure Allocation Against Injection Attacks on Actuators

This article considers the problem of risk-optimal allocation of security measures when the actuators of an uncertain control system are under attack. We consider an adversary injecting false data into the actuator channels. The attack impact is characterized by the maximum performance loss caused by a stealthy adversary with bounded energy. Since the impact is a random variable, due to system uncertainty, we use Conditional Value-at-Risk (CVaR) to characterize the risk associated with the attack. We then consider the problem of allocating the security measures which minimize the risk. We assume that there are only a limited number of security measures available. Under this constraint, we observe that the allocation problem is a mixed-integer optimization problem. Thus we use relaxation techniques to approximate the security allocation problem into a Semi-Definite Program (SDP). We also compare our allocation method $(i)$ across different risk measures: the worst-case measure, the average (nominal) measure, and $(ii)$ across different search algorithms: the exhaustive and the greedy search algorithms. We depict the efficacy of our approach through numerical examples.Comment: Submitted to IEEE Open Journal of Control Systems (OJ-CSYS

Applicability of ecological evaluation tools in estuarine ecosystems: the case of the lower Mondego estuary (Portugal)

Abstract In accordance with the Water Framework Directive guidelines (WFD, 2000, European Communities Official Journal L327 2000/60/EC), classification schemes and ecological evaluation tools (based on benthic invertebrate fauna data sets from 1990 to 2002) were applied in the lower Mondego estuary. Two distinct scenarios could be tested due to the implementation of mitigation practices in 1999, following a long eutrophication process, which started by the early 1980s. Some discrepancies in the results were found by the application of the different indices. The AMBI index (accounting for taxonomic composition) and the ABC method (accounting for abundance and biomass k-dominance patterns) classifications often disagreed with those based on species diversity (Margalef and Shannon-Wiener). The ambiguous results made the classification a complex task to achieve, contrary to the Directive’s objective of maintaining it simple and clear. Our results suggest the necessity of adjusting some of the indices and their ranges to estuarine characteristics, namely to account the typical dominance and abundance of some particular species. These aspects are not taken into consideration by some of the indices proposed, which are more adapted to typical marine conditions. Based on our results, these widely applied indices might still improve their efficiency in estuarine systems allowing their use in the resembling types already established within the new Directive agenda

Gender and politics: A descriptive and comparative analysis of the statutes of Brazilian and Portuguese political parties

This paper presents a descriptive and comparative analysis of the statutes of Brazilian and Portuguese political parties regarding women’s political participation. The main objective was to evaluate if and in what way women are included in the statutory guidelines. By means of the document analysis technique, we analyzed the statutes of political parties represented in the Chamber of Deputies in the case of Brazil and the Assembly of the Republic in the case of Portugal. Our research hypothesis is that although the explanatory potential of party ideology has declined as political parties from different positions on the spectrum have started to adopt discourses in favor of women’s political participation, left-wing parties remain more inclusive in their texts. We could observe that in both countries, leftist parties remain the main encouragers of women’s political participation, at least in their statutory rules.info:eu-repo/semantics/publishedVersio

Implementing gender quotas in Portugal: A success story?

The so-called Portuguese Parity Law adopted in 2006 determined that candidate lists presented for national, European and local elections must include one third minimum representation of each sex. Following its revision in 2019, the minimum percentage required for each sex increased to 40%. The implementation of the Portuguese Parity Law has succeeded in meeting the direct goals of the policy. However, can the same be said for all stages of implementation? Moreover, even when the numbers tell a success story, what practices and resistances do they conceal? And, finally, has the law contributed to gender empowerment that goes beyond the direct scope of the law? This chapter aims to answer these questions by focusing on the national Parliament and on the major Portuguese parties. It draws on the figures for candidates and MPs between 2002 and 2019 as well as on semi-directive interviews with party stakeholders. The main conclusions are the following. First, the implementation of the law takes place smoothly in all four stages of implementation, although parties have usually gone no further than the minimum quota requirements. Parties’ actions and discourses demonstrate a moderate but serious commitment to the law. Second, both explicit and implicit forms of individual resistance, as well as passive institutional resistance take place at the national level for both parties. These resistances are not intended to cause policy failure, but rather to limit policy success. Third, the indirect effects of the law (i.e., gender empowerment in Parliament) are still limited.info:eu-repo/semantics/acceptedVersio

V1647 Ori (IRAS 05436-0007) in Outburst: the First Three Months

We report on photometric (BVRIJHK) and low dispersion spectroscopic observations of V1647 Ori, the star that drives McNeil's Nebula, between 10 February and 7 May 2004. The star is photometrically variable atop a general decline in brightness of about 0.3-0.4 magnitudes during these 87 days. The spectra are featureless, aside from H-alpha and the Ca II infrared triplet in emission, and a Na I D absorption feature. The Ca II triplet line ratios are typical of young stellar objects. The H-alpha equivalent width may be modulated on a period of about 60 days. The post-outburst extinction appears to be less than 7 mag. The data are suggestive of an FU Orionis-like event, but further monitoring will be needed to definitively characterize the outburst.Comment: Accepted for publication in the Astronomical Journa