Effect of the curing time on the numerical modelling of the behaviour of a chemically stabilised soft soil

The ability of the Modified Cam Clay (MCC) model combined with the Von Mises (VM) model, considering the effect of curing time on the enhancement of the mechanical properties of a chemically stabilised soft soil is examined. The evolution of the strength and stiffness over time is based on the results of undrained compressive strength (UCS) tests carried out for different curing times (from 28 days to 360 days). Initially, the MCC/VM models associated with the effect of curing time are validated by CIU triaxial tests, for curing times of 28 and 90 days. Finally, the behaviour of an embankment built on a soft soil reinforced with deep mixing columns is predicted based on the previously validated models. The results show that the increase of curing time of the DMCs slightly decreases the settlement obtained with a curing time of 28 days

Automatic allocation of safety requirements to components of a software product line

Safety critical systems developed as part of a product line must still comply with safety standards. Standards use the concept of Safety Integrity Levels (SILs) to drive the assignment of system safety requirements to components of a system under design. However, for a Software Product Line (SPL), the safety requirements that need to be allocated to a component may vary in different products. Variation in design can indeed change the possible hazards incurred in each product, their causes, and can alter the safety requirements placed on individual components in different SPL products. Establishing common SILs for components of a large scale SPL by considering all possible usage scenarios, is desirable for economies of scale, but it also poses challenges to the safety engineering process. In this paper, we propose a method for automatic allocation of SILs to components of a product line. The approach is applied to a Hybrid Braking System SPL design

Thermodynamic and dynamic anomalies for a three dimensional isotropic core-softened potential

Using molecular dynamics simulations and integral equations (Rogers-Young, Percus-Yevick and hypernetted chain closures) we investigate the thermodynamic of particles interacting with continuous core-softened intermolecular potential. Dynamic properties are also analyzed by the simulations. We show that, for a chosen shape of the potential, the density, at constant pressure, has a maximum for a certain temperature. The line of temperatures of maximum density (TMD) was determined in the pressure-temperature phase diagram. Similarly the diffusion constant at a constant temperature, $D$, has a maximum at a density $\rho_{max}$ and a minimum at a density $\rho_{min}<\rho_{max}$. In the pressure-temperature phase-diagram the line of extrema in diffusivity is outside of TMD line. Although in this interparticle potential lacks directionality, this is the same behavior observed in SPC/E water.Comment: 16 page

Modelling the structural behaviour of rammed earth components

Proceedings of the Twelfth International Conference on Computational Structures Technology, B.H.V. Topping and P. Iványi, (Editors), Civil-Comp Press, Stirlingshire, Scotland.The rammed earth technique has a significant presence in the earthen built heritage, where was used to build from simple dwellings to fortresses. However, the high vulnerability of rammed earth construction to decay agents and to seismic events puts at risk their further existence and the lives of millions of people. With respect to the seismic behaviour of rammed earth walls, the understanding and modelling of their shear behaviour are topics rarely approached in literature. Nevertheless, these topics are of significant importance in the preservation and strengthening of rammed earth constructions. This paper presents experimental and numerical work where the shear behaviour of unstabilised rammed earth is analysed. The experimental program consisted in the testing of several unstabilised rammed earth wallets subject to diagonal compression, which allowed a better understanding of the shear behaviour of unstabilised rammed earth. The numerical work consists of the modelling, of the previous tests, using the finite element method and by considering both the macroand micro-modelling approaches. In general, the numerical models showed a good agreement with the experimental results.The authors would like to thank gratefully the funding provided by the Portuguese Science and Technology Foundation through project FCOMP-01-0124-FEDER-028864 (FCT-PTDC/ECM-EST/2396/2012). Furthermore, the authors wish to express their gratitude to Júlio Machado for his valuable help in the experimental program.info:eu-repo/semantics/publishedVersio

Morphology And Behavior Of The Early Stages Of The Skipper, Urbanus Esmeraldus, On Urera Baccifera, An Ant-visited Host Plant.

The Neotropical genus Urbanus (Hübner) (Lepidoptera: Hesperiidae) contains around 34 described species, and is widely distributed from the extreme southern United States to Argentina. Here, we describe the larval morphology and behavior of Urbanus esmeraldus (Hübner)(Hesperiidae) in Urera baccifera (Urticaceae), a plant producing food rewards and fleshy fruits that attract ants (including predacious species) in a Brazilian forest. Larvae pass through five instars and construct two kinds of leaf shelters. Experiments with ejected fecal pellets showed that these can serve as cues to ground-dwelling ants that climb onto host plants and potentially attack the larvae. Manipulation with pellets placed at different distances suggests that ejection behavior decreases larval vulnerability to ant predation. Larval preference for mature leaves may be related with increased predation risk at ant-visited young leaves. The study shows that a combination of natural history and experimental data can help understand the life history of a butterfly using a plant with high predation risk.125

CdSe quantum dots using polyselenide precursor in soft chemical conditions

CdSe quantum dots were prepared by a simple microemulsion templating technique at low temperature and using common inorganic precursors. Size control was obtained by small variations in reactant concentrations. The chalcogenide source was a polyselenide solution. Narrow (30-40nm fwhm) band gap photoluminescence low defect level and high quantum yield were obtained.FCT and FEDER for financial support to the Research Centre, CFUM [PEst-C/FIS/UI0607/2011 (F-COMP-01-0124-FEDER-022711)] and to the research project PTDC/FIS/113199/200

Interaction of DODAB with neutral phospholipids and cholesterol studied using fluorescence anisotropy

Liposomes composed of cationic lipids and neutral phospholipids have been used as vehicles for cellular delivery of DNA and drug delivery. The aim of this study is to get a better understanding of phospholipid–cationic lipid interactions that is essential for the development of this potential. We have studied the interaction between cationic lipid liposomes primarily composed of dioctadecyldimethylammonium bromide (DODAB) with two different phospholipids, dioleoyl phosphatidylethanolamine (DOPE) and soybean phosphatidylcholine (PC), as well as with cholesterol. The effect of these components on the liposome’s physical properties (microviscosity and polarity) was accessed by studying, both the steady-state and time-resolved, fluorescence anisotropy of the dye Nile Red. This information combined with analysis of the steady-state emission and fluorescence lifetime of Nile Red using the different lipids and cholesterol provided information concerning the polarity and hydration level changes in these vesicle systems along with organisational information

Logic training through algorithmic problem solving

Available for individual study only.Although much of mathematics is algorithmic in nature, the skills needed to formulate and solve algorithmic problems do not form an integral part of mathematics education. In particular, logic, which is central to algorithm development, is rarely taught explicitly at preuniversity level, under the justification that it is implicit in mathematics and therefore does not need to be taught as an independent topic. This paper argues in the opposite direction, describing a one-week workshop done at the University of Minho, in Portugal, whose goal was to introduce to high-school students calculational principles and techniques of algorithmic problem solving supported by calculational logic. The workshop resorted to recreational problems to convey the principles and to software tools, the Alloy Analyzer and Netlogo, to animate models.On- going collaboration with Roland Backhouse is deeply acknowledged. This research was supported by the MathIS project under contract PTDC/ EIA/ 73252/ 2006. The first two authors were further supported by FCT grants SFRH/ BD/ 24269/ 2005 and SFRH/ BD/ 29553/ 2006, respectively

Providing adaptive traffic routing based on user and network context

Providing real-time traffic guarantees and fairness based on the availability of network resources has been a major issue presented in the literature. However, due the convergent nature of digital architectures, the increasing demand of upcoming real-time sensitive traffic, such as VoIP, and a higher user´s adaptability (devices, global positioning, content quality, etc.), solutions based on Quality of Service (QoS) turned out to be insufficient in order to meet user´s requirements. Indeed, QoS metrics are network-centered, and mostly related to the dynamic nature of the traffic (such as throughput, delay, jitter, among others). In order to meet the need for a user-centered network, this paper proposes a context-aware solution where the concepts of Quality of Service, Quality of Experience and Adaptive Routing are integrated in order to provide a more dynamic and pro-active approach for the delivery of context-oriented time-sensitive traffic.info:eu-repo/semantics/publishedVersio