623 research outputs found
Dislocation-twin interactions in nanocrystalline fcc metals
No full textDislocation interaction with and accumulation at twin boundaries have been reported to significantly improve the strength and ductility of nanostructured face-centered cubic (fcc) metals and alloys. Here we systematically describe plausible dislocation interactions at twin boundaries. Depending on the characteristics of the dislocations and the driving stress, possible dislocation reactions at twin boundaries include cross-slip into the twinning plane to cause twin growth or de-twinning, formation of a sessile stair-rod dislocation at the twin boundary, and transmission across the twin boundary. The energy barriers for these dislocation reactions are described and compared. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved
Give Peace A Chance: FCC-State Relations After California III
No full textThe Communications Act of 1934 established a dual regulatory scheme, whereby the FCC has authority over interstate telecommunications service, while the states retain authority over purely intrastate telecommunications. This has led to a border war between the FCC and the states over exactly where the dividing line between their respective regulatory spheres lies. They have also clashed over the scope of permissible FCC preemption of state regulatory authority when that authority conflicts with federal policies. After twenty years of conflict, however, three recent appellate decisions may have provided an opportunity to bring the conflict to an end by clarifying both the boundary between state and federal regulatory authority, and the situations in which the FCC can preempt state regulatory authority.
The Author first examines the basis and history of the FCC-state conflict. While it at first appeared that the FCC\u27s authority versus the states in both the regulatory and preemption spheres would be interpreted very broadly by the courts, later decisions forced the FCC into a strategic retreat from its aggressive regulatory approach. The Author then, relying on three recent appellate decisions, outlines four principles of peaceful coexistence, or guidelines for determining where the dividing line between FCC and state regulatory authority lies and when the FCC can preempt state regulatory policies. The Author argues that: (1) jurisdiction is determined on and end-to-end basis; (2) the FCC has plenary jurisdiction over interstate communications services and facilities; (3) the states are entitled to regulate intrastate communications and facilities; and (4) the FCC may preempt state regulations applicable to carrier-provided intrastate communications facilities or services to the extent enforcement of such regulations would prevent the application of federal regulations to interstate carrier-provided communications services or facilities. Finally, the Author anticipates new areas of potential conflict, and offers preliminary analyses of the issues that might arise
Size-dependent surface energy density of typically fcc metallic nanomaterials
No full textThe surface energy density of nano-sized structural elements exhibits an obvious size-dependent feature. To study this interesting phenomenon, atomistic calculations are carried out in the present paper for different face-centered-cubic (fcc) metallic nano-slabs. Lagrangian and Eulerian descriptions are adopted, respectively, in order to find the varying trends of surface energy densities in an initially un-deformed configuration and a current one. It is found that the Lagrangian surface energy density increases monotonically with an increase of the nano-slab's thickness in the former no matter what the surface orientation is; while the variation of the Eulerian one is indefinite. The surface relaxation parameters are further simulated for differently oriented surfaces, which gives a very good explanation for the differences between the Lagrangian and Eulerian surface energy densities. The results in this paper should be a useful supplement to theoretical studies on the surface/interface effect of nanomaterials
HE-LHC: The High-Energy Large Hadron Collider: Future Circular Collider Conceptual Design Report Volume 4
No full textIn response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100 TeV. Its unprecedented centre-of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries. © 2019, The Author(s)
Jet substructure at Future Circular Collider (FCC)
No full textTitle: Jet substructure at Future Circular Collider (FCC) Author: Tadeáš Petrů Department: Institute of Particle and Nuclear Physics Supervisor: Mgr. Jana Faltová, Ph.D., Institute of Particle and Nuclear Physics Abstract: Future Circular Collider (FCC-hh) is a proposed next-generation hadron collider with a center-of-mass energy of 100 TeV that could be built in CERN. This collider would serve both as a powerful discovery machine and also as a precision measurements machine. One of the challenges for detectors installed at FCC-hh would be an identification of highly boosted objects that subsequently decay hadronically. Within this thesis, we will study the ability of the calorime- ter system of the FCC-hh reference detector in distinguishing two-pronged jets from highly boosted W boson decays and one-pronged jets from light quarks. We will introduce several jet substructure variables and use them as inputs for multivariate analysis (boosted decision trees). Keywords: FCC, substructure, boosted objects ii
Effect of pre-existing defects in the parent fcc phase on atomistic mechanisms during the martensitic transformation in pure Fe: A molecular dynamics study
No full textMolecular dynamics (MD) simulations are used to study the effect of different defect configurations and their arrangements in the parent fcc phase on atomistic mechanisms during the martensitic transformation mechanisms in pure Fe. The defect configurations considered are stacking faults (SF) and twin boundaries (TB) in single crystal fcc. Three arrangements of these defect structures are considered: parallel TB, intersecting SF, and intersecting SF and TB. Each of these defect configurations affect the transformation mechanisms and transformation temperatures. Parallel TB are the lowest-barrier sites for the atomic shear and thus accelerate the transformation process. The fcc phase with parallel TB follows the Nishiyama-Wasserman (NW) martensitic transformation mechanism. On the other hand, intersecting SF impede the atomic shear and thus retard the transformation. The atomistic transformation mechanism in this case first follows the hcp to bcc Burgers path and then the fcc to bcc Olson-Cohen model. The intersecting SF and TB result in a combined effect of both the previous cases. The simulation results show the occurrence of different atomistic mechanisms during martensitic transformation depending on the type of defects present in the parent fcc phase.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.(OLD) MSE-
California v. FCC: A Victory for the States
No full textIn California v. FCC, the Ninth Circuit invalidated the FCC\u27s Computer III Order, a regulatory scheme that changed the method of regulating enhanced services. This Note evaluates the FCC\u27s Computer III Order, focusing on the history of the computer inquiries and the ensuing policy debate between the FCC and state regulatory commissions. The Note analyzes the case law concerning the FCC\u27s preemptive power under the Communications Act of 1934, including the U.S. Supreme Court\u27s decision in Louisiana Public Service Commission and succeeding court of appeal decisions. The author describes the parties\u27 arguments in California v. FCC, explains the Ninth Circuit\u27s decision, and concludes that the court correctly upheld California\u27s authority to regulate intrastate telecommunications\u27services. The Note recommends that Congress amend the Communications Act to require the FCC and the states to engage in negotiated rulemaking when adopting regulations that affect both interstate and intrastate telecommunications services. The author believes that such a process may reduce reliance on courts in resolving disputes over policy
California v. FCC: A Victory for the States
No full textIn California v. FCC, the Ninth Circuit invalidated the FCC\u27s Computer III Order, a regulatory scheme that changed the method of regulating enhanced services. This Note evaluates the FCC\u27s Computer III Order, focusing on the history of the computer inquiries and the ensuing policy debate between the FCC and state regulatory commissions. The Note analyzes the case law concerning the FCC\u27s preemptive power under the Communications Act of 1934, including the U.S. Supreme Court\u27s decision in Louisiana Public Service Commission and succeeding court of appeal decisions. The author describes the parties\u27 arguments in California v. FCC, explains the Ninth Circuit\u27s decision, and concludes that the court correctly upheld California\u27s authority to regulate intrastate telecommunications\u27services. The Note recommends that Congress amend the Communications Act to require the FCC and the states to engage in negotiated rulemaking when adopting regulations that affect both interstate and intrastate telecommunications services. The author believes that such a process may reduce reliance on courts in resolving disputes over policy
California v. FCC: A Victory for the States
No full textIn California v. FCC, the Ninth Circuit invalidated the FCC\u27s Computer III Order, a regulatory scheme that changed the method of regulating enhanced services. This Note evaluates the FCC\u27s Computer III Order, focusing on the history of the computer inquiries and the ensuing policy debate between the FCC and state regulatory commissions. The Note analyzes the case law concerning the FCC\u27s preemptive power under the Communications Act of 1934, including the U.S. Supreme Court\u27s decision in Louisiana Public Service Commission and succeeding court of appeal decisions. The author describes the parties\u27 arguments in California v. FCC, explains the Ninth Circuit\u27s decision, and concludes that the court correctly upheld California\u27s authority to regulate intrastate telecommunications\u27services. The Note recommends that Congress amend the Communications Act to require the FCC and the states to engage in negotiated rulemaking when adopting regulations that affect both interstate and intrastate telecommunications services. The author believes that such a process may reduce reliance on courts in resolving disputes over policy
Molecular dynamics simulations of the mechanisms controlling the propagation of bcc/fcc semi-coherent interfaces in iron
No full textMolecular dynamics simulations have been used to study the effects of different orientation relationships between fcc and bcc phases on the bcc/fcc interfacial propagation in pure iron systems at 300 K. Three semi-coherent bcc/fcc interfaces have been investigated. In all the cases, results show that growth of the bcc phase starts in the areas of low potential energy and progresses into the areas of high potential energy at the original bcc/fcc interfaces. The phase transformation in areas of low potential energy is of a martensitic nature while that in the high potential energy areas involves occasional diffusional jumps of atoms
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