Thermodynamics of Classical Systems on Noncommutative Phase Space

We study the formulation of statistical mechanics on noncommutative classical phase space, and construct the corresponding canonical ensemble theory. For illustration, some basic and important examples are considered in the framework of noncommutative statistical mechanics: such as the ideal gas, the extreme relativistic gas, and the 3-dimensional harmonic oscillator.Comment: 11 pages, no figur

Super-Carrollian and Super-Galilean Field Theories

The exploration of scalar field theories that exhibit Carroll and Galilei symmetries has attracted a lot of attention. In this paper, we generalize these studies to fermionic field theories and construct consistent electric and magnetic descriptions of Carrollian and Galilean spin $\tfrac{1}{2}$ fermions. We showcase various methods that offer complementary perspectives into the limiting process of the underlying relativistic theories. Moreover, we extend our study to $\mathcal{N}=1$ off-shell supersymmetric field theories in four dimensions. By introducing suitable Grassmann-analyticity conditions, we formulate the corresponding super-Carrollian and super-Galilean theories. These theories combine the established Carroll/Galilei scalars with the Carroll/Galilei fermions and a range of auxiliary fields into supermultiplets

Characterization of Tribological and Mechanical Properties of the Si3N4 Coating Fabricated by Duplex Surface Treatment of Pack Siliconizing and Plasma Nitriding on AISI D2 Tool Steel

Abstract Silicon nitride (Si3N4) coating was deposited on AISI D2 tool steel through employing duplex surface treatments—pack siliconizing followed by plasma nitriding. Pack cementation was performed at 650 °C, 800 °C, and 950 °C for 2 and 3 hours by using various mixtures to realize the silicon coating. X-ray diffraction analyses and scanning electron microscopy observations were employed for demonstrating the optimal process conditions leading to high coating adhesion, uniform thickness, and composition. The optimized conditions belonging to siliconizing were employed to produce samples to be further processed via plasma nitriding. This treatment was performed with a gas mixture of 75 pct H2-25 pct N2, at the temperature of 550 °C for 7 hours. The results showed that different nitride phases such as Si3N4-β, Si3N4-γ, Fe4N, and Fe3N can be recognized as coatings reinforcements. It was demonstrated that the described composite coating procedure allowed to obtain a remarkable increase in hardness (80 pct higher with respect to the substrate) and wear resistance (30 pct decrease of weight loss) of the tool steel

The effect of adding Sn on the mechanical properties and microstructure of the titanium

Ti-XSn (X = 0, 5, 10, 15) (wt. %) alloys were prepared by blending TiH2 and Sn powder compact extrusion. The effect of adding tin (Sn) on the microstructure and mechanical properties of titanium has been investigated by optical microscopy and tensile tests. The lamellar thickness (10 to 6.6 µm) of the Ti reduced after adding Sn and according to the Hall-Petch equation the yield strength (548.2 to 801.3 MPa) and microhardness (233.2 to 310 HV) of the Ti is increased with increasing the tin (Sn) content.</p

Characterization and Diffusion Kinetics of Silicon on AISI D2 Steel

This paper presents the simultaneous influence of two different activators (NH4Cl and NaF) on the kinetic evolution during siliconising of steel. The AISI D2 tool steel surface was coated by pack siliconising through the growing of silicon on the surface. Pack siliconising was accomplished by employing a mixture of powders of Si 12 wt% + NH4Cl 0.5 wt% + NaF 0.5 wt% + Al2O3 at 923, 1073 and 1223 K for 1 to 5 h, respectively. The thermodynamics of the different chemical reactions were calculated for the forecast of the coating growth mechanisms of pack siliconising. The microstructure and the precipitation evolution of the silicides were analysed by Energy Dispersive X-ray Spectroscopy line scan (EDS-line scan), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The ranges of the silicide layers thickness resulted between 19 and 337 μm depending on the employed processing parameters. The maximum hardness related to the siliconising parameters for fabricating the different thickness of the intermetallics on the surface of the AISI D2 tool steel and the ranges of the microhardness of the substrate after siliconising is between 750 and 800 HV. The growth of the FeSi, Fe2Si and FeSi2 on the sub-layer is a function of the treatment temperature and time, their growth behavior was used for revealing the kinetics during the process. The results showed that the diffusion coefficient (k) was enhanced by increasing the treatment temperature. Activation energy (Q) resulted 138 KJmol . The crystal growth rate resistance (k) are from 1.141 × 10 - 8 to 1.078×10-6m2s .</p

Modified Wigner equations and continuous spin gauge field

International audienceIn this paper, we first propose the bosonic (fermionic) modified Wigner equations for continuous spin particle (CSP). Secondly, starting from the (Fang-)Fronsdal-like equation, we will reach to the modified action of bosonic (fermionic) continuous spin gauge field in flat spacetime, presented recently by Metsaev in (A)dS spacetime. We shall also explain how to obtain the proposed modified Wigner equations from the gauge-fixed equations of motion. Finally, we will consider the massive bosonic (fermionic) higher-spin action and, by taking the infinite spin limit, we will arrive at the modified bosonic (fermionic) CSP action

Carroll Particle: A Possible Candidate for Dark Matter

The contraction of the Poincar\'e algebra gives rise in two distinct frameworks: Galilean physics and Carrollian physics. While classical Galilean mechanics encompasses well-established relationships for momentum, energy, energy-momentum, and Newton's second law, the corresponding formulas in Carrollian mechanics has remain unknown. This study aims to uncover these formulas within the context of Carrollian mechanics and investigate the thermodynamics of an ideal gas under this framework. The findings reveal a deviation from Galilean mechanics and present a remarkable discovery: Carrollian matter generates an outward gravitational field, in stark contrast to the inward gravitational field observed in Galilean mechanics. Based on this surprising observation, along with additional supporting reasonings, we propose that Carroll particles may be potential candidates for dark matter and may simultaneously provide an explanation for dark energy