Deformation and damage mechanisms of zinc coatings on hot-dip galvanized steel sheets: Part II. Damage modes

Zinc-based coatings are widely used for protection against corrosion of steel-sheet products in the automotive industry. The objective of the present article is to investigate the damage modes at work in three different microstructures of a zinc coating on an interstitial-free steel substrate under tension, planestrain tension, and expansion loading. Plastic-deformation mechanisms are addressed in the companion article. Two main fracture mechanisms, namely, intergranular cracking and transgranular cleavage fracture, were identified in an untempered cold-rolled coating, a tempered cold-rolled coating, and a recrystallized coating. No fracture at the interface between the steel and zinc coating was observed that could lead to spalling, in the studied zinc alloy. A complex network of cleavage cracks and their interaction with deformation twinning is shown to develop in the material. An extensive quantitative analysis based on systematic image analysis provides the number and cumulative length of cleavage cracks at different strain levels for the three investigated microstructures and three loading conditions. Grain refinement by recrystallization is shown to lead to an improved cracking resistance of the coating. A model for crystallographic cleavage combining the stress component normal to the basal plane and the amount of plastic slip on the basal slip systems is proposed and identified from equibiaxial tension tests and electron backscattered diffraction (EBSD) analysis of the cracked grains. This analysis requires the computation of the nonlinear stress-strain response of each grain using a crystal-plasticity constitutive model. The model is then applied successfully to other loading conditions and is shown to account for the preferred orientations of damaged grains observed in the case of plane-strain tension.     

First derivation of predicted-no-effect values for freshwater and terrestrial ecosystems exposed to radioactive substances

The FASSET Radiation Effects Database (FRED) constitutes a unique structured resource of the biological effects of ionizing radiation on non-human species mainly from temperate ecosystems, encompassing 26,000 primary data entries. Quality-assessed data were extracted from FRED and dose-effect relationships were constructed to provide estimates of ED50 and EDR10. These estimates are Doses (or Dose Rates) related to the percent change in the average level of the endpoint for a particular effect (50% or 10% for acute or chronic exposure regimes, respectively). Acute and chronic Species Sensitivity Distributions (SSDs) were built on the basis of these data sets, and the Assessment Factor Method (AFM) was applied when data were too scarce. The Hazardous Dose corresponding to 5% of species acutely affected at the 50% effect level varied from 1 to 5.5 Gy according to the ecosystem. For chronic gamma external irradiation exposure, no-effect values varied from 10 microGy/h for freshwaters through application of the AFM to 67 microGy/h for terrestrial ecosystems, corresponding to the 5th percentile of the non-weighted SSD (vs 229 microGy/h when trophic weights are applied). These values are higher by ca. x50 to x100 than the upper bound of natural background, and lower than dose rates triggering effects at individual levels on contaminated sites.     

Effect of surfactants on liquid-side mass transfer coefficients in gas-liquid systems: A first step to modeling

This paper focuses on the effect of surfactants on the mass transfer parameters (volumetric mass transfer coefficient k_La and liquid-side mass transfer coefficient k_L). Tap water and aqueous solutions with surfactants (anionic, cationic and non-ionic at concentrations up to are used as liquid phases. The bubbles are generated into a small-scale bubble column having an elastic membrane with a single orifice as gas sparger. To understand the effects of the surfactants on the mass transfer, not only the static surface tension is used, but also the characteristic adsorption parameters like the surface coverage ratio at equilibrium Se. The liquid-side mass transfer coefficient is obtained from the ratio of the volumetric mass transfer coefficient (measured by a chemical method) and the specific interfacial area. These two parameters are obtained simultaneously. The methods used to obtain these parameters are described in Painmanakul et al. [2005. Effects of surfactants on liquid-side mass transfer coefficients. Chemical Engineering Science 60, 6480-6491].Whatever the liquid phase, three zones are found on the liquid-side mass transfer coefficient variation with the bubble diameter. For bubble diameters less than 1.5 mm, whatever the liquid phases, the k_L values are roughly constant at . For bubble diameters greater than 3.5 mm, the k_L values do not vary much with the bubble diameter, but depend on the surfactant concentration. For bubble diameters between 1.5 and 3.5 mm, the k_L values increase from to the value reached at 3.5 mm. This increase depends on the surfactants. Higbie's model does not represent the k_L values for bubble diameters greater than 3.5 mm, even though there is a small amount of surfactant in the liquid phase. Thus, a model is proposed for each zone described above. Explanations are also proposed for the effect of the surfactant on the k_L values for each of the above zones.     

Dissolved and bioavailable contaminants in the Seine river basin

Diffusive Gradient in Thin Films (DGT) and Semi-Permeable Membrane Devices (SPMDs) were deployed in the Seine river basin in order to assess labile metals and truly dissolved Polycyclic Aromatic Hydrocarbons. We show that the tools are reliable in aquatic environments to assess the speciation of dissolved contaminants and hence provide a good insight into the potential bioavailability of contaminants. The deployment of the DGT and SPMDs in contrasting environments in the Seine river basin allowed distinction to be made of availability of contaminants between headwater streams and much more impacted river reaches and an assessment of bioavailability. At the stations under urban influence, the impact of dissolved organic matter on both copper and PAHs bioavailability is less pronounced than at upstream stations, where humic substances dominate.     

Application of molecular beam deflection time-of-flight mass spectrometry to peptide analysis

The application of molecular beam deflection time-of-flight mass spectrometry (MBD-TOFMS) to peptide identification is described. The technique permits a simultaneous measurement of molecular mass and electric dipole susceptibility. The mass and susceptibility are not strongly correlated, and the results can be presented as a two-dimensional map. The susceptibility provides a useful way to disperse isobaric and isomeric peptides, and at least for small peptides, the susceptibility is significantly different for different amino acid sequences. Results for peptides in the mass range 1000-2300 Da show that the mass and susceptibility lead to a higher identification score than mass spectra alone.     

The industrial management of SMEs in the era of Industry 4.0

Industry 4.0 provides new paradigms for the industrial management of SMEs. Supported by a growing number of new technologies, this concept appears more flexible and less expensive than traditional enterprise information systems such as ERP and MES. However, SMEs find themselves ill-equipped to face these new possibilities regarding their production planning and control functions. This paper presents a literature review of existing applied research covering different Industry 4.0 issues with regard to SMEs. Papers are classified according to a new framework which allows identification of the targeted performance objectives, the required managerial capacities and the selected group of technologies for each selected case. Our results show that SMEs do not exploit all the resources for implementing Industry 4.0 and often limit themselves to the adoption of Cloud Computing and the Internet of Things. Likewise, SMEs seem to have adopted Industry 4.0 concepts only for monitoring industrial processes and there is still absence of real applications in the field of production planning. Finally, our literature review shows that reported Industry 4.0 projects in SMEs remained cost-driven initiatives and there in still no evidence of real business model transformation at this time.     

Space-time Generalized Riemann Problem Solvers of Order k for Linear Advection with Unrestricted Time Step

This work concerns high-order approximations of the linear advection equation in very long time. A GRP-type scheme of arbitrary high-order in space and time with no restriction on the time step is developed. In the usual GRP solvers, we consider a polynomial approximation of the solution in space in each cell at the initial time. Here, we add a second polynomial approximation of the solution in time in each interface. Thanks to this double approximation, the resulting scheme is compact. It is proved to be of order k+1 in space and time, where k is the degree of the polynomials. Thanks to the compactness of the scheme, a two-dimensional extension is detailed on unstructured meshes made of triangles. Several numerical test-cases and comparison with existing methods illustrate the excellent behaviour of the scheme.     

Data visualization via latent variables and mixture models: a brief survey

In the literature, data visualization is extensively studied via diverse parametric probabilistic distributions for the exploration of continuous, binary, and counting data. An overview of the existing methods for non-symmetric data matrices is presented in an unified framework via the Bernoulli law and binary variables. An extension to continuous or counting variables is available by using instead any another univariate distribution such as the Poisson or Gaussian one. Several approaches are possible when the model is with a distribution on the rows, the columns, the row clusters, the column clusters, the cells, the blocks, or a transformed matrix of the distances from the pairs of rows or columns. The objective functions are presented with their full expressions in separated sections, one for each method: Kohonen’s map and related methods of self-organizing maps, generative topographic mapping as a probabilistic self-organizing map, linear principal component analysis and related matricial methods (non-negative factorization, factorization), probabilistic parametric embedding, probabilistic latent semantic visualization, latent cluster position model, t-distributed stochastic neighbor embedding. The conclusion is a discussion of the contribution with perspectives.     

Isomorphic coupled-task scheduling problem with compatibility constraints on a single processor

The problem presented in this paper is a generalization of the usual coupled-tasks scheduling problem in presence of compatibility constraints. The reason behind this study is the data acquisition problem for a submarine torpedo. We investigate a particular configuration for coupled tasks (any task is divided into two sub-tasks separated by an idle time), in which the idle time of a coupled task is equal to the sum of durations of its two sub-tasks. We prove \(\mathcal{NP}\)-completeness of the minimization of the schedule length, we show that finding a solution to our problem amounts to solving a graph problem, which in itself is close to the minimum-disjoint-path cover (min-DCP) problem. We design a \((\frac{3a+2b}{2a+2b})\)-approximation, where a and b (the processing time of the two sub-tasks) are two input data such as a>b>0, and that leads to a ratio between \(\frac {3}{2}\) and \(\frac{5}{4}\). Using a polynomial-time algorithm developed for some class of graph of min-DCP, we show that the ratio decreases to \(\frac{1+\sqrt{3}}{2}\approx 1.37\).