Structures and photophysical properties of 3,4-diaryl-1H-pyrrol-2,5-diimines and 2,3-diarylmaleimides

Structural features of 3,4-diaryl-1H-pyrrol-2,5-diimines and their derivatives have been studied by molecular spectroscopy techniques, single-crystal X-ray diffraction, and DFT calculations. According to the theoretical calculations, the diimino tautomeric form of 3,4-diaryl-1H-pyrrol-2,5-diimines is more stable in solution than the imino-enamino form. We also found that the structurally related 2,3 exist in the solid state in the dimeric diketo form. 3,4-Diary1-1H-pyrrol-2,5-diimines and 2,3-diarylmaleimides exhibit fluorescence in the blue region of the visible spectrum. The fluorescence spectra have large Stokes shifts. Aryl substituents at the 3,4-positions of 1H-pyrrol-2,5-diimine do not significantly affect fluorescence properties. The insertion of donor substituents into 2,3diarylmaleimides leads to bathochromic shift of emission bands with hyperchromic effect. (C) 2017 Elsevier B.V. All rights reserved

Detailed structural analysis of a graded TF coil winding pack for EU DEMO

The toroidal field (TF) coil system is one of the most mechanically stressed systems in a tokamak. Structural integrity of the system must be maintained on the global and on the local scale, where the stress state in each conductor jacket as well as in the insulation is to be within structural allowable limits. Solving this task head-on leads to very high computational demands. In this work a methodology for a finite element (FE) detailed analysis of a graded TF coil winding pack (WP) for EU DEMO is presented. A graded WP design option was analyzed in detail in critical locations of the coil, which were identified by an approximate, but very fast approach developed earlier. A comparison with the said approach was made to verify its applicability and limitations. The presented procedure proved to be accurate requiring only moderate computational efforts. The parametric approach allows fast implementation of design changes into the model. The procedure can be used to speed up the assessment of future design iterations of the DEMO TF coil system

Strategies of Numerical Modeling in Component Development for Fusion Devices

The development of components for fusion devices includes numerous simulations to validate their design compatibility with specified loads according to applicable codes and standards. The strategy of multifield finite element analyses is determined by the iterative nature of the design process. The level of structural complexity dictates the analytical approaches and modeling techniques. Even though nowadays powerful software exploiting the performance of modern computers allows structures to be simulated in a very detailed way, direct meshing of CAD models with all their complexity is often not beneficial for nonlinear and multifield analyses. Reasonable modeling simplifications, submodeling, and integration with analytical modeling and testing can optimize the analysis process. This paper gives examples of simplified modeling for engineering purposes with a clear understanding of the analysis goal and the role of simulations in the design process, such as for the W7-X stellarator busbar system. Engineering methods to perform multifield analyses including electromagnetic transients for ITER diagnostic port plug components are also presented. An engineering material model is discussed for calculating the superconducting coil steel structures operating in the inelastic range