3,470 research outputs found
A three-node C deg element for analysis of laminated composite sandwich shells
A three-node flat shell element with C deg rotation fields has been developed for analysis of arbitrary composite shells. The element may consist of any number of orthotropic layers, each layer having different material properties and angular orientation. The formulation includes coupling between bending and extension, which is essential for analysis of unsymmetric laminates. Shearing deflections are included, since laminated and sandwich construction frequently results in shear stiffness much smaller than bending stiffness. Formulation of the element is straightforward, and calculation of its stiffness matrix is simple and fast. Convergence of solutions with mesh refinement is uniform for both thin and thick shells and is insensitive to element shape, although not as rapid as some other elements that lack one or more capabilities of the newly developed element. An experimental verification of the shall element is reported in the appendix
Expected Sensitivity to Galactic/Solar Axions and Bosonic Super-WIMPs based on the Axio-electric Effect in Liquid Xenon Dark Matter Detectors
We present systematic case studies to investigate the sensitivity of axion
searches by liquid xenon detectors, using the axio-electric effect (analogue of
the photoelectric effect) on xenon atoms. Liquid xenon is widely considered to
be one of the best target media for detection of WIMPs (Weakly Interacting
Massive Particles which may form the galactic dark matter) using nuclear
recoils. Since these detectors also provide an extremely low radioactivity
environment for electron recoils, very weakly-interacting low-mass particles (<
100 keV/c^2), such as the hypothetical axion, could be detected as well - in
this case using the axio-electric effect. Future ton-scale liquid Xe detectors
will be limited in sensitivity only by irreducible neutrino background
(pp-chain solar neutrino and the double beta decay of 136Xe) in the mass range
between 1 and 100 keV/c^2. Assuming one ton-year of exposure, galactic axions
(as non-relativistic dark matter) could be detected if the axio-electric
coupling g_Ae is greater than 10^-14 at 1 keV/c^2 (or $10^-13 at 100 keV/c^2).
Below a few keV/c^2, and independent of the mass, a solar axion search would be
sensitive to a coupling g_Ae ~ 10^-12. This limit will set a stringent upper
bound on axion mass for the DFSV and KSVZ models for the mass ranges m_A < 0.1
eV/c^2 and < 10 eV/c^2, respectively. Vector-boson dark matter could also be
detected for a coupling constant alpha'/alpha > 10^-33 (for mass 1 keV/c^2) or
> 10^-27 (for mass 100 keV/c^2).Comment: 17 pages, 10 figure
Superconducting gap structure of FeSe
The microscopic mechanism governing the zero-resistance flow of current in
some iron-based, high-temperature superconducting materials is not well
understood up to now. A central issue concerning the investigation of these
materials is their superconducting gap symmetry and structure. Here we present
a combined study of low-temperature specific heat and scanning tunnelling
microscopy measurements on single crystalline FeSe. The results reveal the
existence of at least two superconducting gaps which can be represented by a
phenomenological two-band model. The analysis of the specific heat suggests
significant anisotropy in the gap magnitude with deep gap minima. The tunneling
spectra display an overall "U"-shaped gap close to the Fermi level away as well
as on top of twin boundaries. These results are compatible with the anisotropic
nodeless models describing superconductivity in FeSe.Comment: 8 pages, 5 figure
Characterization of the Hamamatsu R11410-10 3-Inch Photomultiplier Tube for Liquid Xenon Dark Matter Direct Detection Experiments
To satisfy the requirements of the next generation of dark matter detectors
based on the dual phase TPC, Hamamatsu, in close collaboration with UCLA, has
developed the R11410-10 photomultipler tube. In this work, we present the
detailed tests performed on this device. High QE (>30%) accompanied by a low
dark count rate (50 Hz at 0.3 PE) and high gain (10^7) with good single PE
resolution have been observed. A comprehensive screening measurement campaign
is ongoing while the manufacturer quotes a radioactivity of 20 mBq/PMT. These
characteristics show the R11410-10 to be particularly suitable for the
forthcoming zero background liquid xenon detectors.Comment: 19 pages, 18 figure
TO USE A TREE OR A FOREST IN BEHAVIORAL INTENTION
Cloud computing is a new technology that has been applied to education and has e nabled the development of cloud computing classrooms; however, student behavioral intentions toward cloud computing remain unclear. Most researchers have evaluated, integrated, or compared few (1 to 3) theories to examine user behavioral intentions and few have addressed additional theories or models. In this study, we test, compare, and unify six well -known theories, namely, service quality (SQ), self - efficacy (SE), the motivational model (MM), technology acceptance model (TAM), theory of reason action (TRA)/theory of planned behavior (TPB), and innovation diffusion theory (IDT) in the context of cloud computing classrooms. This empirical study was conducted using an online survey. The data collected from the samples (n=478) were analyzed using structural equation modeling. We independently analyzed each of the six theories, formulating a united model. The analysis yielded three valuable findings. First, comparing the explained variance and degree of freedom (df) difference, yielded the following ranking in explained variance: MM=TAM\u3eIDT\u3eTPB\u3eSE=SQ (equal =; superior to\u3e). Second, comparing the explained variance yielded the following ranking in explained variance: MM\u3eTAM\u3eIDT\u3eTPB\u3eSE=SQ. Third, based on the united model of six theories, some factors significantly affect behavioral intention and others do not. The implications of this study are critical for both researchers and practitioners
XAX: a multi-ton, multi-target detection system for dark matter, double beta decay and pp solar neutrinos
A multi-target detection system XAX, comprising concentric 10 ton targets of
136Xe and 129/131Xe, together with a geometrically similar or larger target of
liquid Ar, is described. Each is configured as a two-phase
scintillation/ionization TPC detector, enhanced by a full 4pi array of
ultra-low radioactivity Quartz Photon Intensifying Detectors (QUPIDs) replacing
the conventional photomultipliers for detection of scintillation light. It is
shown that background levels in XAX can be reduced to the level required for
dark matter particle (WIMP) mass measurement at a 10^-10 pb WIMP-nucleon cross
section, with single-event sensitivity below 10^-11 pb. The use of multiple
target elements allows for confirmation of the A^2 dependence of a coherent
cross section, and the different Xe isotopes provide information on the
spin-dependence of the dark matter interaction. The event rates observed by Xe
and Ar would modulate annually with opposite phases from each other for WIMP
mass >~100 GeV/c^2. The large target mass of 136Xe and high degree of
background reduction allow neutrinoless double beta decay to be observed with
lifetimes of 10^27-10^28 years, corresponding to the Majorana neutrino mass
range 0.01-0.1 eV, the most likely range from observed neutrino mass
differences. The use of a 136Xe-depleted 129/131Xe target will also allow
measurement of the pp solar neutrino spectrum to a precision of 1-2%.Comment: 16 pages with 17 figure
Numerical CFD Simulation and Test Correlation in a Flight Project Environment
This paper presents detailed description of a novel CFD procedure and comparison of its solution results to that obtained by other available CFD codes as well as actual flight and wind tunnel test data pertaining to the GIII aircraft, currently undergoing flight testing at AFRC
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