Application of the Resources Model to the Supervision of an Automated Process

The present study was designed to ascertain how far flagging up potential errors can improve the automatic interpretation of technical documents. We used the resources model to analyze the supervised retro-conversion of architectural floor plans from the perspective of distributed cognition. Results showed that automated assistance helps users to correct errors spotted by the system and saves time. Surprisingly, they also showed that flagging up possible errors may make users less effective in identifying and correcting errors that go unnoticed by the system. Responses to a questionnaire probing the participants’ confidence in the system suggested that they were so trusting that they lowered their vigilance in those areas that had not been signaled by the system, leading to the identification of fewer errors there. Thus, although the participants’ confidence in the automated assistance system led to improved performances in those areas it highlighted, it also meant that areas to which the system did not draw attention were less thoroughly checked.     

Efficient implementation of the implicit error correction nVoD schema

Implicit Error Correction is a near Video-on-Demand (nVoD) schema that trades bandwidth utilization for initial playback delay while potentially allowing an infinite number of users. Additionally, it provides error protection without further bandwidth increase by exploiting the implicit redundancy of nVoD protocols, using linear combinations of the segments transmitted in a given time slot. This paper introduces a new implementation that outperforms the original schema by adding two new mechanisms: redundancy channels and feedback error correction.     

A Java Framework to Specify Faultloads for Fault Injection Campaigns

In an operational environment, the identification and reproduction of faults may be hard to be done, specially in complex systems. Use of fault injection accelerates this process, improving the test of fault tolerance mechanisms. However, there are a significant amount of fault injectors available, using several different approaches. This diversity of tools, each one with different methods to describe faultloads for fault injection campaigns, imposes severe obstacles to the efficient use of such fault injectors. In this context, this paper presents jFaultload, which applies Java for the specification of faultloads and translates them to specific formats that are appropriate to each available fault injector. Fault injectors for communication systems were integrated in the environment and completes the test scenario. The service under test used to demonstrate the usability and expressiveness of our solution is a video streaming session using RTP Protocol.     

Migration induced material transport in Cu–Sn IMC and SnAgCu microbumps

Microbumps consisting of intermetallic compounds like Cu₆Sn₅ or Cu₃Sn have a longer lifetime during electromigration tests than SnAgCu microbumps. To explain the difference in behavior of Cu–Sn IMCs and SnAgCu during stress test the migration induced mass flux was calculated for Cu₃Sn and Cu₆Sn₅. The results were compared to the mass flux in SnAgCu 305. Furthermore average effective charge values for Cu₃Sn and Cu₆Sn₅ were approximated by comparing the separated movement of Cu and Sn with three different models for an averaged mass flux in the IMCs.     

Solid state transformations of Au-Cu-Pt alloys studied by in-situ X-ray synchrotron radiation and DSC

Seven alloys of the ternary Au-Cu-Pt system, containing 75 or 76.5 wt.% Au with 0–15 wt.% Pt and heat-treated to a fully ordered condition, are examined using in-situ synchrotron radiation to determine transformation temperatures and phases formed, and to investigate mechanisms of ordering and disordering. These experiments are complemented by differential scanning calorimetry. Diffraction data show that the alloys can be separated into three groups according to their stable low-temperature ordered phase(s), namely L1₀, L1₂, or the two combined. Platinum increases transformation temperatures in comparison with binary AuCu, two-phase ordered alloys showing the highest transformation temperatures. Details of the evolution of the X-ray diffraction peak structures upon heating and cooling point to significant differences between mechanisms of disordering and ordering: whereas ordering visibly proceeds at significant undercooling by nucleation and growth, disordering appears, from the visible shifts in peak position, to progress in more homogeneous fashion within the alloy.     

Influence of superplasticizers on pore solution composition and on expansion of concrete due to alkali-silica reaction

The use of superplasticizers (SP) is widespread in today’s concrete production. Usually, SP are used when specific demands in regard to workability, strength or durability have to be met. As they contain sodium sulphate, they have the potential to increase the alkalinity in the pore solution and the risk of damages due to alkali-silica reaction. In this study, the effect of two SP on the potential reactivity of concrete is examined by analyzing pore solutions of pastes and mortars and by measuring concrete expansion. The use of a naphthalene–sulphonate-based SP (Na content referred to liquid: 2.8%) leads to an increase in hydroxide concentration in the pore solution during the first two weeks going together with an accelerated concrete expansion during this period. The effects of a polycarboxylate-based SP (Na content referred to liquid: 0.5%) are less pronounced and do not result in an increased concrete expansion.     

Influence of clay in limestone fillers for self-compacting cement based composites

High workability together with a good resistance to segregation is needed for cement based composites, specifically fresh self-compacting mortars (SCM); in this prospect, the amount of coarse materials has to be reduced and replaced by fine material. Several limestone fillers are here compared and analysed. These by-products are issued from different industrial sectors, such as the aggregate and lime production industry (quarrying operations) and the ornamental stones industry (sawing operations).Particular attention has been paid to clay content, as consistency of fresh mortars was varying, while other physical characteristics like granulometry remained the same. Relationship between the physico-chemical properties of the fillers and the properties of fresh and hardened mortars are brought forward. Even if it may affect fresh properties of mortars, results clearly show that clay type and content has minor influence than limestone filler itself.     

A formulation to model the nonlinear viscoelastic properties of the vascular tissue

Nearly all soft tissues, including the vascular tissue, present a certain degree of viscoelastic material response, which becomes apparent performing multiple relaxation tests over a wide range of strain levels and plotting the resulting stress relaxation curves, nonlinear viscoelasticity of the tissue. Changes in relaxation rate at each strain may occur at multiple strain levels. A constitutive formulation considering the particular features of the vascular tissue, such as anisotropy, together with these nonlinear viscoelastic phenomena is here presented and used to fit stress?Cstretch curves from experimental relaxation tests. This constitutive model was used to fit several data set of in vitro experimental stress relaxation tests performed on ovine and porcine aorta. The good fitting of the experimental data shows the capability of the model to reproduce the viscoelastic response of the vascular tissue.