Ricerc@Sapienza

A time-domain analysis is presented of the transient field excited by a vertical electric dipole on a graphene sheet described through a local scalar conductivity model valid in the intraband regime. The analysis is carried out by means of the double-deformation method of Tsang and Kong [J. Math. Phys. 20, 1170 (1979)JMAPAQ0022-248810.1063/1.524169], a modified modal technique which allows for defining a causal surface-plasmon-polariton (SPP) contribution to the total transient field that is also computationally very efficient for a graphene sheet.

The classical problem represented by a planar thin conductive shield in the presence of vertical dipole field sources (electric or magnetic) is solved analytically in the time domain via the Cagniard-de Hoop technique. Comparisons with numerical solutions carried out by means of efficient integration algorithms are provided and discussed.

An integrated FT-ICR and computational approach has been employed to investigate the gas phase structure and reactivity of ESI-formed complexes between organic and inorganic acids (HX) and a K+-containing hexaazamacrocycle (M). Two limiting structures are available to those complexes, either the classical [MK+·XH] or the zwitterionic [MH+·K+·X?] one, with the latter prevailing over the first by increasing the gas-phase acidity of the HX ligand.

Offshore wind towers may influence each other in the presence of faults or lightning strokes through the grounding system and the leakage currents. These phenomena are investigated by taking into account the non-uniform media surrounding the towers. In particular, simplified (in the quasistatic approximation) analytical expressions for the ground resistance are provided, and their numerical validation is presented, with specific reference to actual types of foundations currently adopted.

Pure nickel coatings were directly plated onto steel by using an electroless plating process. The effect of different synthesis strategies on the morphological surface was investigated and the study of growth mechanisms has provided useful information about the surface properties of coating. In this paper, several plating parameters (pH, temperature, solution composition and the ratio between the sample surface area and the volume of solution) were investigated by studying their influence on the plating rate. High thickness (30 μm) coatings were obtained after 2 h of plating at 85 °C.

TiO2-SiO2 mixed oxides have been prepared by the sol–gel technique from tetrabutyl orthotitanate and tetraethyl orthosilicate. The prepared materials were characterized by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, nitrogen physisorption, Fourier-transform infrared spectroscopy (FT-IR) and x-ray photoelectron spectroscopy (XPS). The results indicate that the TiO2-SiO2 mixed oxides have a large surface area and a nanoscale size. FT-IR spectra show that Ti atoms are bonded to silica by oxygen bridging atoms in Ti-O-Si bonds.

Intermetallic titanium aluminides have attracted considerable industrial interest for aero and automotive applications owing to their specific strength. These alloys are candidates for high-temperature applications such as turbine blades and turbocharger turbine wheels. In this work, the mechanical behaviour of an as-cast Ti–47Al–3Cr–3Nb (at.-%) alloy was studied. Four-point bending tests were performed to determine the mechanical properties of the alloy at both room and high temperatures. Microhardness and Young’s modulus were evaluated by dynamic indentation tests at room temperature.

Stellite 6 is a cobalt-base alloy commonly used for coatings useful in wear and corrosion protection of several components over a wide range of temperatures. Stellite coatings can be obtained by many deposition techniques: plasma transferred arc (PTA) is certainly an optimal choice that gives thick, dense coatings, but thermal spray techniques like high velocity oxy-fuel (HVOF) are also widely used to deposit such materials.

In the present paper, the fatigue behaviour of a near-equiatomic pseudo-elastic NiTi SMA (Shape Memory Alloy) is experimentally examined by means of tensile cyclic loading tests. In situ X-ray Diffraction (XRD) analyses are also performed in order to measure the contents of both austenite and martensite phase during testing. The experimental campaign highlights a stress–strain diagram defined through five different stress–strain functions.

Mixing of a diffusing species entrained in a three-dimensional microfluidic flow-focusing cross-junction is numerically
investigated at low Reynolds numbers, 1 ≤ Re ≤ 150 , for a value of the Schmidt number representative of a small solute
molecule in water, Sc = 103 . Accurate three-dimensional simulations of the steady-state incompressible Navier–Stokes equations
confirm recent results reported in the literature highlighting the occurrence of different qualitative structures of the