Analysis of Digital Twin Definition and Its Difference from Simulation Modelling in Practical Application

The digital twin is widely known as a tool for digitalization of a product, but there is no common definition concerning this term. This article discusses the definition and utilization of digital twin. Areas of use, it’s implementation in the product lifecycle and most importantly it’s benefits. The lack of a standardized concept of a digital  twin leads to a misunderstanding between mathematical models and digital twin. Several definitions of digital twin were analyzed and compared with the definition of mathematical model and simulation modelling. The basic concept of areas of use for digital twin is introduced. The differences and similarities between the two definitions were found. The article aims first of all to help the management of digital twins in practical application. Keywords: Digital twin, Mathematical modelling, Mathematical model, Lifecycle of a product, Simulation modelling, Practical use of digital twin, Difference between the digital twin and mathematical model, Simulation

Selection of Elements at the Dissolution of Heat Resistant Nickel Alloys in Mineral Acid Solutions

Thermodynamic modeling of the interaction of a heat-resistant nickel alloy containing refractory rare metals with hydrochloric, sulfuric and nitric acids with a temperature change in the range of 20-100 ∘ C and a concentration of 50 to 150 g / dm3 at a pressure of 1 atm was carried out. The thermodynamic assessment data were confirmed in experiments on the anodic dissolution of the alloy in sulfate solutions. According to the results of x-ray phase analysis of the sludge, it was revealed that tungsten in the form of a solid solution in nickel passes to this product. Also, tantalum and niobium pass into the slurry in the form of oxides. Mostly, Re, Co, Cr passed into the electrolyte solution. The results of the study can serve as a scientific basis for the development of promising technologies for processing metal waste from heat-resistant alloys. Keywords: thermodynamic modeling, heat resistant nickel alloy, rare elements, mineral acids, dissolutio

Optimization of single crystal mirrors for ITER diagnostics

Diagnostic mirrors are planned to be used in all optical diagnostics in ITER. Degradation of mirrors due to e.g. deposition of plasma impurities will hamper the entire performance of affected diagnostics. in situ mirror cleaning by plasma sputtering is presently envisaged for the recovery of contaminated mirrors. There are observations showing a signature of sputtering dependence on crystal orientation. Should such a dependence exist, the sputtering of single crystal mirrors could be minimized, thus prolonging a mirror lifetime. Four single crystal molybdenum mirrors with different orientations were produced to study the effect of crystal orientation on sputtering. Mirrors were exposed to argon plasma under identical plasma conditions relevant to those expected in the mirror cleaning systems of ITER. The energy of impinging ions was about 60 eV. The amount of sputtered material corresponded to about a hundred mirror cleaning cycles in argon. Plasma exposures did not affect the mirror reflectivity. The maximum decrease of specular reflectivity did not exceed 5% at 250 nm. The mirrors with orientations [110]/[101] demonstrated up to 42% less sputtering than the mirrors with other crystal orientations. These findings outline the advantage of a favorable crystal orientation for a cleaning of heavy contaminants from ITER mirrors.Peer reviewe