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Effect of metal elements in catalytic growth of carbon nanotubes
No full textUsing first-principles calculations, we model the chemical vapor deposition (CVD) growth of carbon nanotubes (CNT) on nanoparticles of late-transition (Ni, Pd, Pt) and coinage (Cu, Ag, Au) metals. The process is analyzed in terms of the binding of mono- and diatomic carbon species, their diffusion pathways, and the stability of the growing CNT. We find that the diffusion pathways can be controlled by the choice of the catalyst and the carbon precursor. Binding of the CNT through armchair edges is more favorable than through zigzag ones, but the relative stability varies significantly among the metals. Coinage metals, in particular Cu, are found to favor CVD growth of CNTs at low temperatures and with narrow chirality distributions.CSE
The CMS trigger system
No full textThis paper describes the CMS trigger system and its performance during Run 1 of the LHC. The trigger system consists of two levels designed to select events of potential physics interest from a GHz (MHz) interaction rate of proton-proton (heavy ion) collisions. The first level of the trigger is implemented in hardware, and selects events containing detector signals consistent with an electron, photon, muon, τ lepton, jet, or missing transverse energy. A programmable menu of up to 128 object-based algorithms is used to select events for subsequent processing. The trigger thresholds are adjusted to the LHC instantaneous luminosity during data taking in order to restrict the output rate to 100 kHz, the upper limit imposed by the CMS readout electronics. The second level, implemented in software, further refines the purity of the output stream, selecting an average rate of 400 Hz for offline event storage. The objectives, strategy and performance of the trigger system during the LHC Run 1 are described.LPH
Gossip-Based Peer Sampling
No full textGossip-based communication protocols are appealing in large-scale distributed applications such as information dissemination, aggregation, and overlay topology management. This paper factors out a fundamental mechanism at the heart of all these protocols: the peer-sampling service. In short, this service provides every node with peers to gossip with. We promote this service to the level of a first-class abstraction of a large-scale distributed system, similar to a name service being a first-class abstraction of a local-area system. We present a generic framework to implement a peer-sampling service in a decentralized manner by constructing and maintaining dynamic unstructured overlays through gossiping membership information itself. Our framework generalizes existing approaches and makes it easy to discover new ones. We use this framework to empirically explore and compare several implementations of the peer-sampling service. Through extensive simulation experiments we show that—although all protocols provide a good quality uniform random stream of peers to each node locally—traditional theoretical assumptions about the randomness of the unstructured overlays as a whole do not hold in any of the instances. We also show that different design decisions result in severe differences from the point of view of two crucial aspects: load balancing and fault tolerance. Our simulations are validated by means of a wide-area implementation.DC
turboTDDFT 2.0 Hybrid functionals and new algorithms within time-dependent density-functional perturbation theory
No full textWe present a new release of the turboTDDFT code featuring an implementation of hybrid functionals, a recently introduced pseudo-Hermitian variant of the Liouville-Lanczos approach to time-dependent density-functional perturbation theory, and a newly developed Davidson-like algorithm to compute selected interior eigenvalues/vectors of the Liouvillian super-operator. Our implementation is thoroughly validated against benchmark calculations performed on the cyanin (C21O11H21) molecule using the Gaussian 09 and turboTDDFT 1.0 codes. Program summary Program title: turboTDDFF 2.0 Catalogue identifier: AEIX_v2_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEDCv2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License, version 2 No. of lines in distributed program, including test data, etc.: 5995995 No. of bytes in distributed program, including test data, etc.: 122184812 Distribution format: tar.gz Programming language: Fortran 95, MAI. Computer: Any computer architecture. Operating system: GNU/Linux, AIX, IRIX, Mac OS X, and other UNIX-like OS's. Classification: 16.2, 16.6, 7.7. External routines: turboTDDFT 2.0 is a tightly integrated component of the Quantum ESPRESSO distribution and requires the standard libraries linked by it: BIAS, LAPACK, FFTW, MPI. Does the new version supercede the previous version?: Yes Nature of problem: Calculation of the optical absorption spectra of molecular systems. Solution method: Electronic excited states are addressed by linearized time-dependent density-functional theory within the plane-wave pseudo-potential method. The dynamical polarizability can be computed in terms of the resolvent of the Liouvillian super-operator, using a pseudo-Hermitian variant of the Lanczos recursion scheme. As an alternative, individual eigenvalues of the Liouvillian can be computed via a newly introduced variant of the Davidson method. In both cases, hybrid functionals can now be used. Reasons for new version: To implement new features. Summary of revisions: New features implemented: 1. Hybrid functionals. 2. Pseudo-Hermitian Lanczos recursion algorithm. 3. All-new Davidson-like solver for the Liouvillian eigenvalue equation ("Casida equation"). Restrictions: Spin-restricted formalism. Linear-response regime. Adiabatic XC kernels only. Hybrid functionals are only accessible using norm-conserving pseudo-potentials. Unusual features: No virtual orbitals are used, nor even calculated. Within the Lanczos method a single recursion gives access to the whole optical spectrum; when computing individual excitations using the Davidson method, interior eigenvalues can be easily targeted. Additional comments: !!!!! The distribution file for this program is over 121 Mbytes and therefore is not delivered directly when download or E-mail is requested. Instead a html file giving details of how the program can be obtained is sent. Running time: From a few minutes for small molecules on serial machines up to many hours on multiple processors for complex nanosystems with hundreds of atoms. (C) 2014 Elsevier B.V. All rights reserved.IM
Structural rigidity theory applied to the scaffold-free (dis)assembly of space frames using cooperative robotics
No full textCRC
A case for DOT: Theoretical Foundations for Objects with Pattern Matching and GADT-Style Reasoning
No full textMany programming languages in the OO tradition now support pattern matching in some form. Historical examples include Scala and Ceylon, with the more recent additions of Java, Kotlin, TypeScript, and Flow. But pattern matching on generic class hierarchies currently results in puzzling type errors in most of these languages. Yet this combination of features occurs naturally in many scenarios, such as when manipulating typed ASTs. To support it properly, compilers needs to implement a form of subtyping reconstruction: the ability to reconstruct subtyping information uncovered at runtime during pattern matching. We introduce cDOT, a new calculus in the family of Dependent Object Types (DOT) intended to serve as a formal foundation for subtyping reconstruction. Being descended from pDOT, itself a formal foundation for Scala, cDOT can be used to encode advanced object-oriented features such as generic inheritance, type constructor variance, F-bounded polymorphism, and first-class recursive modules. We demonstrate that subtyping reconstruction subsumes GADTs by encoding lambda(2,G mu), a classical constraint-based GADT calculus, into cDOT.LAMP
(re)connecting Heijplaat, Rotterdam: Project for a transPORT museum
No full textPartout dans le Monde, les activités portuaires quittent les villes. Cette mouvance est principalement due à la globalisation des marchés et des moyens de transport qui provoquent de graves conséquences en terme de planification urbaine et environnementale. Ce phénomène se manifeste avec force à Rotterdam, où les quartiers du port vivent, depuis plus de 80 ans, un déplacement lent et progressif vers la côte ayant comme effet la libération de vastes surfaces le long du fleuve, souvent très proches du centre ville. Régional À la grande échelle, le défi majeur s'avère être la re-connexion entre Port et Ville. Depuis toujours envisagée de manière isolée, le quartier du CityPorts paraît pouvoir offrir un nouveau potentiel d'urbanité. Le rapprochement de ces deux fractions de Rotterdam devient donc nécessaire. Local Plus de 20'000 personnes travaillent dans les quelques 850 entreprises installées sur les 1400 ha du CityPorts (partie du port située dans le périmètre de la Ville de Rotterdam). 2'000 d'entre eux habitent le «village oasis» de Heijplaat, une enclave habitée, entièrement entouré par des infrastructures portuaires. La péninsule de Heijplaat symbolise aujourd'hui la charnière entre Rotterdam Zuid et le contexte portuaire. Les trois "têtes" définissant la bordure de la Meuse en sont la façade. En complément de Quarantaine Eiland et du RDM district, deux portions de territoire pour lesquelles une destination thématique est en partie déjà programmée, nous proposons un troisième pôle, plus public et entièrement dédié à la couture d'un lien entre les échelles humaine et portuaire, locale et globale: un musée des transports et de la mobilité.SAR-DLABALTH1Cote: 2007.039Archive: MEM.1/2 autre, MEM.2/2 autre, CD.1/1Groupe de suivi: Gugger Harry (dir. pédagogique); Lucan Jacques (prof.); Blättler Ralph (maître EPFL); Kees Christiaanse (expert
