Parametric thermal analysis for the optimization of Double Walled Tubes layout in the Water Cooled Lithium Lead inboard blanket of DEMO fusion reactor

Within the roadmap that will lead to the nuclear fusion exploitation for electric energy generation, the construction of a DEMOnstration (DEMO) reactor is, probably, the most important milestone to be reached since it will demonstrate the technological feasibility and economic competitiveness of an industrial-scale nuclear fusion reactor. In order to reach this goal, several European universities and research centres have joined their efforts in the EUROfusion action, funded by HORIZON 2020 UE programme. Within the framework of EUROfusion research activities, ENEA and University of Palermo are involved in the design of the Water-Cooled Lithium Lead Breeding Blanket (WCLL BB), that is one of the two BB concepts under consideration to be adopted in the DEMO reactor. It is mainly characterized by a liquid lithium-lead eutectic alloy acting as breeder (lithium) and neutron multiplier (lead), as well as by subcooled pressurized water as coolant. Two separate circuits, both characterized by a pressure of 15.5 MPa and inlet/outlet temperatures of 295 °C/328 °C, are deputed to cool down the First Wall (FW) and the Breeder Zone (BZ). The former consists in a system of radial-toroidal-radial C-shaped squared channels where countercurrent water flow occurs while the latter relies in the use of bundles of poloidal-radial Double Walled Tubes (DWTs) housed within the breeder. A parametric thermal study has been carried out in order to assess the best DWTs' layout assuring that the structural material maximum temperature does not overcome the allowable limit of 550 °C and that the overall coolant thermal rise fulfils the design target value of 33 °C. The study has been performed following a theoretical-numerical approach based on the Finite Element Method (FEM) and adopting the quoted Abaqus FEM code. Main assumptions and models together with results obtained are herewith reported and critically discussed

Peak Ventilation Reference Standards from Exercise Testing: From the FRIEND Registry

Peak Ventilation Reference Standards from Exercise Testing: From the FRIEND Registry. Med. Sci. Sports Exerc., Vol. 50, No. 12, pp. 2603–2608, 2018. Purpose: Cardiopulmonary exercise testing (CPX) provides valuable clinical information, including peak ventilation (V˙ Epeak), which has been shown to have diagnostic and prognostic value in the assessment of patients with underlying pulmonary disease. This report provides reference standards for V˙ Epeak derived from CPX on treadmills in apparently healthy individuals. Methods: Nine laboratories in the United States experienced in CPX administration with established quality control procedures contributed to the Fitness Registry and the Importance of Exercise National Database from 2014 to 2017. Data from 5232 maximal exercise tests from men and women without cardiovascular or pulmonary disease were used to create percentiles ofV˙ Epeak for both men and women by decade between 20 and 79 yr. Additionally, prediction equations were developed for V˙ Epeak using descriptive information. Results: V˙ Epeak was found to be significantly different between men and women and across age groups (P G 0.05). The rate of decline in V˙ Epeak was 8.0% per decade for both men and women. A stepwise regression model of 70% of the sample revealed that sex, age, and height were significant predictors ofV˙ Epeak. The equation was cross-validated with data from the remaining 30% of the sample with a final equation developed from the full sample (r = 0.73). Additionally, a linear regression model revealed forced expiratory volume in 1 s significantly predicted V˙ Epeak (r = 0.73). Conclusions: Reference standards were developed for V˙ Epeak for the United States population. Cardiopulmonary exercise testing laboratories will be able to provide interpretation of V˙ Epeak from these age and sex-specific percentile reference values or alternatively can use these nonexercise prediction equations incorporating sex, age, and height or with a single predictor of forced expiratory volume in 1 s

Antiferromagnetic phase of the gapless semiconductor V3Al

Discovering new antiferromagnetic compounds is at the forefront of developing future spintronic devices without fringing magnetic fields. The antiferromagnetic gapless semiconducting D03 phase of V3Al was successfully synthesized via arc-melting and annealing. The antiferromagnetic properties were established through synchrotron measurements of the atom-specific magnetic moments, where the magnetic dichroism reveals large and oppositely-oriented moments on individual V atoms. Density functional theory calculations confirmed the stability of a type G antiferromagnetism involving only two-third of the V atoms, while the remaining V atoms are nonmagnetic. Magnetization, x-ray diffraction and transport measurements also support the antiferromagnetism. This archetypal gapless semiconductor may be considered as a cornerstone for future spintronic devices containing antiferromagnetic elements.Comment: Accepted to Physics Review B on 02/23/1

Comportamiento a la flexión y absorción de humedad en placas de aglomerado y polipropileno reciclado

La fabricación de placas aglomeradas tiene dos inconvenientes importantes: el consumo de madera virgen y la emisión de VOC’s (compuestos orgánicos volátiles), localizados en el adhesivo utilizado, que tienen consecuencias ambientales ampliamente documentadas. Para mitigar estos efectos, se han realizado experiencias de conformación de placas sustituyendo en parte la madera virgen por material reciclado, el cual elimina además la necesidad de utilizar adhesivos. Este trabajo muestra los resultados obtenidos en los ensayos de flexión y de absorción de humedad de placas hechas a escala piloto, con distintas proporciones de madera y polipropileno reciclado, y su comparación con los valores de placas comerciales de un espesor semejante. Estos resultados resultan alentadores, ya que si bien presentan amplia variabilidad dada su conformación a escala no industrial, con las placas conformadas con material reciclado se están alcanzando valores de resistencia a la flexión cercanos a los comerciales en los ensayos realizados, y en la absorción de humedad los resultados son mejores que en las comerciales.Fil: Rivarola, A.. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Rojo, L.. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Arena, Alejandro Pablo. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentin

Synchronization of fractional order chaotic systems

The chaotic dynamics of fractional order systems begin to attract much attentions in recent years. In this brief report, we study the master-slave synchronization of fractional order chaotic systems. It is shown that fractional order chaotic systems can also be synchronized.Comment: 3 pages, 5 figure