1,530 research outputs found

    Variations on a Theme of Glauberman

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    A new and elementary proof of the Artin–Zorn theorem that finite alternative division rings are fields is given. The characterisation of finite fields of Glauberman and Heimbeck is also extended to a broader class of fields, the two subjects being connected via geometry

    Boron-10 Lined Proportional Counter Wall Effects

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    The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube based system in the configuration of a coincidence counter. This report provides information about how variations in proportional counter radius and gas pressure in a typical coincident counter design might affect the observed signal from boron-lined tubes. A discussion comparing tubes to parallel plate counters is also included

    On fractional Choquard equations

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    We investigate a class of nonlinear Schrodinger equations with a generalized Choquard nonlinearity and fractional diffusion. We obtain regularity, existence, nonexistence, symmetry as well as decays properties.Comment: revised version, 22 page

    MOSE: Salvare Venezia

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    Since 1900, the water levels in the Venetian Lagoon have risen almost 16 centimeters. In the same timeframe the city of Venice has gone from averaging 7 floods a year to over 100 in 2004 alone. It’s clear that in order for Venice to survive this problem a solution must be found. Fortunately, in 2003 MOSE (Modulo Sperimentale Elettromeccanico), a network of floodgates constructed at each entrance to the lagoon that prevents flooding during high tides, finally began its long awaited construction, that today is in its final stages. When looking at MOSE from an engineering perspective, the mechanics behind the system are actually quite simple. However, considering the magnitude of the project, they are incredibly important to understand thoroughly and to analyze correctly. This project seeks to understand the mechanical system that is currently in place, analyzing it in such a way in order to explain the strength of the floodgates

    Stable standing waves for a class of nonlinear Schroedinger-Poisson equations

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    We prove the existence of orbitally stable standing waves with prescribed L2L^2-norm for the following Schr\"odinger-Poisson type equation \label{intro} %{%{ll} i\psi_{t}+ \Delta \psi - (|x|^{-1}*|\psi|^{2}) \psi+|\psi|^{p-2}\psi=0 \text{in} \R^{3}, %-\Delta\phi= |\psi|^{2}& \text{in} \R^{3},%. when p∈{8/3}âˆȘ(3,10/3)p\in \{8/3\}\cup (3,10/3). In the case 3<p<10/33<p<10/3 we prove the existence and stability only for sufficiently large L2L^2-norm. In case p=8/3p=8/3 our approach recovers the result of Sanchez and Soler \cite{SS} %concerning the existence and stability for sufficiently small charges. The main point is the analysis of the compactness of minimizing sequences for the related constrained minimization problem. In a final section a further application to the Schr\"odinger equation involving the biharmonic operator is given

    Towards a comprehensive taxonomy for characterizing robots

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    Every day a new robot is developed with advanced characteristics and technical qualities. The increasingly rapid growth of robots and their characteristics demands bridging between the application requirements and the robot specifications. This process requires a supporting conceptual structure that can capture as many robot qualities as possible. Presenting robot characteristics through the proposed conceptual structure would enable designers to optimize robot capabilities against application requirements. It would also help application developers to select the most appropriate robot. Without a formal structure, an accurate linking between the robot domain and the application domain is not possible. This paper presents a novel theoretical representation that can capture robot features and capabilities and express them as descriptive dimensions to be used to develop a capability profile. The profile is intended to unify robot description and presentation. The proposed structure is reinforced with several layers, sections, categorizations and levels to allow a detailed explanation of robot characteristics. It is hoped that the proposed structure will influence the design, development, and testing of robots for specific applications. At the same time, it would help in highlighting the corresponding outlines in robot application requirements

    Boron-10 Lined Proportional Counter Model Validation

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    The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project “Coincidence Counting With Boron-Based Alternative Neutron Detection Technology” at Pacific Northwest National Laboratory (PNNL) for the development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube-based alternative system in the configuration of a coincidence counter. This report discusses the validation studies performed to establish the degree of accuracy of the computer modeling methods current used to simulate the response of boron-lined tubes. This is the precursor to developing models for the uranium neutron coincidence collar under Task 2 of this project
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