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The influence of deep cryogenic treatment on the erosive wear performance of Stainless Steel-316L (SS-316L) used in hydropower plants is studied. For this purpose, several SS-316L samples were held at deep cryogenic temperatures (−196 °C) for different soaking periods (12, 24, 36 h). The erosive wear tests were conducted on a self-fabricated slurry erosion test rig and the same was evaluated by weighing the cumulative mass loss (CML) of samples for every 30 min post erosion. From experimental analysis, it was found that the erosive wear was found to be minimum and the hardness reaches to maximum value after 24 h of the soaking period which could be attributed to the significant microstructural changes such as the transformation of γ-austenite phase into (δ-ferrite+α′-martensite) along with precipitation of numerous carbides after deep cryogenic treatments.

In the present work, two different hardfacings, namely SZ (Super-Zed alloy; C3.83Cr33.37) and ZK (Zedalloy-K; C0.65Cr4.5Mo8.18) were deposited on EN-47 ploughshare steel by manual metal arc welding process to enhance the abrasive wear resistance. In addition, the influence of heat-treatment of steel by two different methods, i.e., carburizing (C) and through-hardening (Q&T), on the abrasive wear behaviour has also been investigated. Abrasive wear studies were conducted on bare, hardfaced, and heat-treated steel in a laboratory by using a three-body dry sand rubber wheel test rig as per the ASTM G-65 standard. The bare steel suffered a high wear rate, which may be attributed to its soft ferritic-pearlitic microstructure. The abrasive wear rate of tested specimens was found to be 1.7651 × 10−3 g m−1, 0.7439 × 10−3 g m−1, 0.961 × 10−3 g m−1, 0.992 × 10−3 g m−1 and 1.21 × 10−3 g m−1 for bare, SZ, ZK, C and Q&T steel specimens respectively. The SZ hardfacing provided better abrasive wear protection than the other treatments due to high chromium and carbon concentration in the hardfacings electrodes, which presented a higher area fraction of primary M7C3 carbides in the matrix. The wear resistance indices (WRI) for SZ hardfacing, ZK hardfacing, carburized, and through-hardened steel specimens were found to be 2.37, 1.84, 1.78, and 1.46, respectively.

In the last decades the landslide assessment plays a crucial role in land use development in order to minimize the negative effect of economic live and people’s health. This paper present a GIS based landslide susceptibility assessment. This model is applied on the Littoral Coast line from Constanta to 2 Mai village, which is about 50 km along the Black Sea coast, crossing the Danube – Black Sea Channel at Agigea and passing through several resorts – Eforie Nord, Eforie Sud, Techirghiol, Costinesti and Mangalia. The data used are: geological map (lithology per geologic group), topographic maps of relevant scale to define slope angle (β), and some geotechnical parameters per geological group. For each of them a GIS map was produced. Based on the research results, we could conclude that Landslide Susceptibility Area (LSA) maps represent a great tool used in the identification of areas predisposed to landslides and could be used as support in the decision-maker process in order to propose environmental work protection or county planning.

Techirghiol Lake is one of the most important hypersaline lakes in South East region of Europe due in particular to its therapeutic properties. The principal threats of this ecosystem are: climate changes and watershed changes due to human activities, which result in pronounced changes of this lake. The analysis of changes (via parametric and nonparametric approaches) is one of the keystones for understanding the long term variability of this ecosystem and the factors influencing it. To analyse the evolution of lake processes the hydro-meteorological variables was investigated, spanning the 1953-2015 period. The preliminary results shows a strongly influence of anthropic impact corroborate with climate changes on hydrological lake variables.

Groundwater is a natural resource indispensable for life and for most economic activities. Due to its presentation in time and space, groundwater becomes vulnerable to hazardous phenomena of different origin, natural or anthropogenic, that can produce disturbances in some water systems or default situations. Parametric models can be used to model the groundwater vulnerability and with the help of Geographical Information System (GIS) we can make the results of a complicated parametric model more clearly through visual representation. To achieve the above objective, the empirical model known as “DRASTIC” developed in USA by the Environmental Protection Agency (EPA) [1] as a way to produce a relative-risk scale of potential groundwater vulnerability to pollution that could be applied to a large area was adopted and tested with GIS to identify areas from Dobrogea Region (Romania) where the groundwater is more or less susceptible to pollution.

The Spitzer Survey of Stellar Structure in Galaxies S^4G is an Exploration Science Legacy Program approved for the Spitzer post-cryogenic mission. It is a volume-, magnitude-, and size-limited (d 30 degrees, m_(Bcorr) 1') survey of 2,331 galaxies using IRAC at 3.6 and 4.5 microns. Each galaxy is observed for 240 s and mapped to > 1.5 x D25. The final mosaicked images have a typical 1 sigma rms noise level of 0.0072 and 0.0093 MJy / sr at 3.6 and 4.5 microns, respectively. Our azimuthally-averaged surface brightness profile typically traces isophotes at mu_3.6 (AB) (1 sigma) ~ 27 mag arcsec^-2, equivalent to a stellar mass surface density of ~ 1 Msun pc^-2. S^4G thus provides an unprecedented data set for the study of the distribution of mass and stellar structures in the local Universe. This paper introduces the survey, the data analysis pipeline and measurements for a first set of galaxies, observed in both the cryogenic and warm mission phase of Spitzer. For every galaxy we tabulate the galaxy diameter, position angle, axial ratio, inclination at mu_3.6 (AB) = 25.5 and 26.5 mag arcsec^-2 (equivalent to ~ mu_B (AB) =27.2 and 28.2 mag arcsec^-2, respectively). These measurements will form the initial S^4G catalog of galaxy properties. We also measure the total magnitude and the azimuthally-averaged radial profiles of ellipticity, position angle, surface brightness and color. Finally, we deconstruct each galaxy using GALFIT into its main constituent stellar components: the bulge/spheroid, disk, bar, and nuclear point source, where necessary. Together these data products will provide a comprehensive and definitive catalog of stellar structures, mass and properties of galaxies in the nearby Universe.

The addition of Ti and/or Ta to commercial multifilamentary Nb3Sn wires is commonly used to increase their upper critical field, and thus the critical current density at high fields. We have compared the critical parameters (Tc and Bc2) and the critical current densities Jc at 17 and 21 T for several multifilamentary quaternary (Nb,Ti,Ta)3Sn wires prepared by the bronze route process. The goal of this work is to establish a correlation between the Ti content and the superconducting properties (Tc, Bc2, Jc) of these wires. We have found that Ti additions do not lead to a further increase of Tc and Bc2 in quaternary (Nb,Ta,Ti)3Sn wires with respect to ternary (Nb,Ta)3Sn wires. On the other hand, the highest Jc was measured in quaternary (Nb,Ta,Ti)3Sn wires (1.5 at.% Ti with respect to the Nb–7.5% Ta cores), where Ti was added to the bronze matrix. It was found that the wire configuration has only a small effect on Tc and Bc2.

The lattice parameter changes in three types of Nb3Sn superconducting wires during uniaxial stress–strain measurements at 4.2 K have been measured by high-energy synchrotron x-ray diffraction. The nearly-stress-free Nb3Sn lattice parameter has been determined using extracted filaments, and the elastic strain in the axial and transverse wire directions in the different wire phases has been calculated. The mechanical properties of the PIT and RRP wire are mainly determined by the properties of Nb3Sn and unreacted Nb. This is in contrast to the bronze route wire, where the matrix can carry substantial loads. In straight wires the axial Nb3Sn pre-strain is strongest in the bronze route wire, its value being smaller in the PIT and RRP wires. A strong reduction of the non-Cu elastic modulus of about 30% is observed during cool-down from ambient temperature to 4.2 K. The Nb3Sn Poisson ratio at 4.2 K measured in the untwisted bronze route wire is 0.35. The present study also shows that the process route has a strong influence on the Nb3Sn texture.

With the aim of clarifying the relationship between lattice deformations and superconducting properties of Nb3Sn technological wires we have carried out high-energy x-ray diffraction experiments at the European Synchrotron Radiation Facility (ESRF) in Grenoble on individual samples of multi-filamentary internal-tin-type Nb3Sn wires. In particular, a test probe developed at the University of Geneva allowed us to perform these experiments at 4.2 K, while applying an axial tensile load to the specimen. In this way, the lattice parameter values of all the constituents (Nb3Sn, Nb, Cu) were determined, in both the parallel and orthogonal directions with respect to the applied load axis, as a function of the applied strain. The experiments were performed on industrial wires, which were reinforced by a stainless steel outer tube, applied before the Nb3Sn reaction heat treatment, in order to evaluate the effect of an additional pre-compression strain. The relation between the microscopically determined crystalline lattice deformations and the measured applied strain is discussed as a basis for the analysis of the superconducting performances of Nb3Sn wires subject to mechanical loads.

The evolution of Nb containing phases during the diffusion heat treatment of three different high critical current Nb3Sn strand types is compared, based on synchrotron X-ray diffraction results that have been obtained at the ID15 beam line of the European Synchrotron Radiation Facility (ESRF). In all strands studied, Nb3Sn formation is preceded by the formation of a Cu-Nb-Sn ternary phase, NbSn2 and Nb6Sn5. As compared to the PIT and Tube Type strand, the amount of these phases formed in the RRP strand is relatively small. In the RRP strand subelements with a fine filament structure Nb3Sn grows more quickly, thereby preventing to a large extent the formation of the other higher tin phases.

The critical current density in industrial Nb3Sn and MgB2 wires is currently optimized by introducing various kinds of additives, either Ta and/or Ti for Nb3Sn wires or SiC or C for MgB2 wires. In the following, several problems linked to the presence of additives in the two classes of compounds are discussed. A reinvestigation of the site occupancy of Ta and Ti additives in Nb3Sn wires shows that the Ta atoms occupy the 6c chain sites, while the Ti atoms are located on the cubic 2a sites. It follows that in perfectly ordered A15 compounds A1−βBβ, the relation ρo versus β exhibits a 'universal' behavior: the effect of the chemical nature of the constituents on ρo is negligible. The slopes of ρ0 versus the Ti, Ga and Ni contents in the A15 layer coincide and are much steeper than for the Ta additive, corresponding to the three times higher number of 6c sites with respect to 2a A15 lattice sites. The presence of two grain morphologies, e.g. equiaxial and columnar, is observed in Nb3Sn wires produced by the bronze route only. The nonlinearity of the Kramer plot in multifilamentary Nb3Sn bronze route wires is explained by the presence of these two different grain types, which have distinctly different Sn contents and sizes. For these wires, the total pinning force can be represented as the superposition of two contributions with different scaling fields. Simultaneous addition of different additives on 'in situ' Fe/MgB2 wires is presented as an attempt to combine different possible mechanisms influencing Jc. The substitution of boron by carbon is known to enhance the value of ρo and thus of the critical field. In addition, the pinning behavior is expected to be improved by grain boundary effects or nanosize precipitations, caused by the presence of appropriate additives during the MgB2 phase formation. Since the two mechanisms are independent, their effect on Jc is expected to be cumulative. In the present paper, the results on the additive combination B4C+LaB6 in monofilamentary Fe sheathed MgB2 wires are reported. The data are compared with the additives B4C+SiC and show that simultaneous additives could be promising in view of applications at 20 K.

The inner, outer, and nuclear rings and pseudorings of early to intermediate Hubble type spiral galaxies offer the best evidence for the detectability of specific orbit resonances in normal galaxies. Here I briefly summarize my work on the statistical and morphological properties of outer rings and pseudorings, and how these properties relate the rings to the outer Lindblad resonance.