2,409 research outputs found

    Hamiltonian reductions of the one-dimensional Vlasov equation using phase-space moments

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    We consider Hamiltonian closures of the Vlasov equation using the phase-space moments of the distribution function. We provide some conditions on the closures imposed by the Jacobi identity. We completely solve some families of examples. As a result, we show that imposing that the resulting reduced system preserves the Hamiltonian character of the parent model shapes its phase space by creating a set of Casimir invariants as a direct consequence of the Jacobi identity

    European and International Law and Palestinian Refugees: Bolbol, El Kott and the Application of Article 1D of the Geneva Convention

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    This paper explores the recent Court of Justice of the European Union (CJEU) judgments of El Kott and Bolbol, and the implications of those judgments on the interpretation and application of Article 1D. In the first part, I seek to give a brief overview of the purpose of Article 1D, as regards the Palestinian refugee population. I then go on to look at the interpretations adopted in the Bolbol and El Kott judgments of the CJEU. In the final part of this paper, I explore the difficulties of assessing indiscriminate violence in light of the CJEU judgments, by referring to the stance adopted by other international and national courts. In particular, I establish that requiring an individualisation of the risk goes against the purpose of Article 1D

    Hamiltonian closures for fluid models with four moments by dimensional analysis

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    Fluid reductions of the Vlasov-Amp{\`e}re equations that preserve the Hamiltonian structure of the parent kinetic model are investigated. Hamiltonian closures using the first four moments of the Vlasov distribution are obtained, and all closures provided by a dimensional analysis procedure for satisfying the Jacobi identity are identified. Two Hamiltonian models emerge, for which the explicit closures are given, along with their Poisson brackets and Casimir invariants

    Kinematics of the New Zealand plate boundary: Relative motion by GPS across networks of 1000 km and 50 km spacing

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    The NASA/DOSE 'Kinematics of the New Zealand Plate Boundary' experiment is a four-year cooperative Global Positioning System (GPS) experiment involving 6 universities and institutions in New Zealand and the United States. The investigation covers two scales, the first on the scale of plates (approximately 1000 km) and the second is on the scale of the plate boundary zone (approximately 50 km). In the first portion of the experiment, phase A, the objective is to make direct measurements of tectonic plate motion between the Australian and Pacific plates using GPS in order to determine the Euler vector of this plate pair. The phase A portion of this experiment was initiated in December 1992 with the first-epoch baseline measurements on the large scale network. The network will be resurveyed two years later to obtain velocities. The stations which were observed for phase A are shown and listed. Additional regional stations which will be used for this study are listed and are part of either CIGNET or other global tracking networks. The phase A portion of the experiment is primarily the responsibility of the UNAVCO investigators. Therefore, this report concentrates on phase A. The first year of NASA funding for phase A included only support for the field work. Processing and analysis will take place with the second year of funding. The second part of the experiemnt measured relative motion between the Australian and Pacific plates across the pate boundary zone between Hokitika and Christchurch on the South Island of New Zealand. The extent and rate of deformation will be determined by comparisons with historical, conventional surveys and by repeated GPS measurements to be made in two years. This activity was the emphasis of the LDGO portion of the study. An ancillary experiment, phase C, concentrated on plate boundary deformation in the vicinity of Wellington and was done as part of training during the early portion of the field campaign. Details of the objectives of the field investigations are given in the appendix. An overview of the 1992 GPS field program is also given in the appendix

    Drawing the Glitch

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    Dynamic Composite Data Physicalization Using Wheeled Micro-Robots

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    This paper introduces dynamic composite physicalizations, a new class of physical visualizations that use collections of self-propelled objects to represent data. Dynamic composite physicalizations can be used both to give physical form to well-known interactive visualization techniques, and to explore new visualizations and interaction paradigms. We first propose a design space characterizing composite physicalizations based on previous work in the fields of Information Visualization and Human Computer Interaction. We illustrate dynamic composite physicalizations in two scenarios demonstrating potential benefits for collaboration and decision making, as well as new opportunities for physical interaction. We then describe our implementation using wheeled micro-robots capable of locating themselves and sensing user input, before discussing limitations and opportunities for future work

    Status of the Construction of the First 15 m Long Superconducting Dipole Prototype for the LHC

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    CERN and INFN are jointly building the first full-size superconducting dipole prototype for the LHC. This magnet, whose construction was launched in spring 1995, is completely manufactured in industry . Its fabrication required the upgrade of the tooling which was used to build three 10-m long prototypes under a previous CERN-INFN Collaboration. The construction is being completed and the cryostate d magnet is expected to be at CERN for testing by the end of 1997. In this paper we discuss the results of the measurements carried out at 4.2 K and 2 K to determine the conductor properties (Ic of wi res and cables, magnetization), as well as the short sample limit. The main features of the coil construction are presented, together with the results of the main fabrication phases. In particular, th e validity of the fabrication techniques is assessed based on the obtained results

    Avaliação agronômica de pastagens manejadas em um sistema de pastejo rotacionado no Estado do Amazonas.

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    Este trabalho teve como objetivo avaliar aspectos produtivos de modelos de sistemas de pastejo rotacionado intensivo visando a determinar aspectos da pastagem e da produção animal
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