2,448 research outputs found

    Mechanical design of NASA Ames Research Center vertical motion simulator

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    NASA has designed and is constructing a new flight simulator with large vertical travel. Several aspects of the mechanical design of this Vertical Motion Simulator (VMS) are discussed, including the multiple rack and pinion vertical drive, a pneumatic equilibration system, and the friction-damped rigid link catenaries used as cable supports

    On Aharonov-Casher bound states

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    In this work bound states for the Aharonov-Casher problem are considered. According to Hagen's work on the exact equivalence between spin-1/2 Aharonov-Bohm and Aharonov-Casher effects, is known that the E\boldsymbol{\nabla}\cdot\mathbf{E} term cannot be neglected in the Hamiltonian if the spin of particle is considered. This term leads to the existence of a singular potential at the origin. By modeling the problem by boundary conditions at the origin which arises by the self-adjoint extension of the Hamiltonian, we derive for the first time an expression for the bound state energy of the Aharonov-Casher problem. As an application, we consider the Aharonov-Casher plus a two-dimensional harmonic oscillator. We derive the expression for the harmonic oscillator energies and compare it with the expression obtained in the case without singularity. At the end, an approach for determination of the self-adjoint extension parameter is given. In our approach, the parameter is obtained essentially in terms of physics of the problem.Comment: 11 pages, matches published versio

    On the influence of a Coulomb-like potential induced by the Lorentz symmetry breaking effects on the Harmonic Oscillator

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    In this work, we obtain bound states for a nonrelativistic spin-half neutral particle under the influence of a Coulomb-like potential induced by the Lorentz symmetry breaking effects. We present a new possible scenario of studying the Lorentz symmetry breaking effects on a nonrelativistic quantum system defined by a fixed space-like vector field parallel to the radial direction interacting with a uniform magnetic field along the z-axis. Furthermore, we also discuss the influence of a Coulomb-like potential induced by Lorentz symmetry violation effects on the two-dimensional harmonic oscillator.Comment: 14 pages, no figure, this work has been accepted for publication in The European Physical Journal Plu

    Miljøovervåking i Sandefjordsfjorden og Indre Mefjorden 1997/98. Kartlegging av kilder til miljøgifter

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    Klororganiske miljøgifter i vannmassene ble registrert over en fire-ukers periode høsten 1997 ved hjelp av aktive (blåskjell) og passive (SPMD) akkumulatorer utplassert i bøyerigger på kontrollstasjoner og i potensielle kildeområder i Sandefjordsfjorden og utenfor Kastet fyllplass i Mefjorden. Hvorvidt stasjonene ble påvirket av aktive kilder ble vurdert på grunnlag av geografiske variasjonsmønstre og statistisk prinsipalkomponent-analyse av PCB-profilene fra hver enkelt rigg. Resultatene viste forhøyete konsentrasjoner av klorbenzener på alle stasjoner. Kastet syntes å representere en kilde til DDT og i noe mindre grad PCB. I Sandefjordsfjorden ble det funnet flere sannsynlige kilder til både DDT og PCB. De klart høyeste konsentrasjoner av PCB ble funnet innerst i Kamfjordkilen, men også i nærheten av Jotun, Vera deponi og Kastet synes aktive kilder å forekomme. Tilførslene fra kilder lenger ute i fjorden i nærheten av Jotun og deponiet på Vera kan i noen grad være kamuflert av bedre vannutskifting og raskere fortynning

    Wartime Experiences and Popular Support for Peace Agreements: Comparative Evidence from Three Cases

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    Peace agreements are negotiated and signed by representatives of the government and the rebels, often after many years of violent conflict, but their ability to transform a war-torn society hinges on the approval of ordinary people. Yet we have little systematic knowledge of what ordinary people think of peace agreements in the long run. This study begins to fill that gap, drawing on a set of comparative public opinion surveys from Guatemala, Nepal, and Northern Ireland, three cases where long civil wars were ended by peace agreements. The peace agreements in these countries have strong popular support, though there is variation across specific provisions. Across these cases, our findings suggest that legacies of violence are not generally associated with long-term support for peace agreements. However, when we look at provisions that grant concessions to the rebels, there is some evidence of lasting legacies
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