11,849 research outputs found
Recent Results Addressing the KARMEN Timing Anomaly
Recent resuls from experiments at Fermilab and the Paul Scherrer Institute
have constrained the parameter space available for a hypothetical particle
produced in the decay . This decay has been invoked
to explain a peculiar feature of an event arrival time distribution observed in
the KARMEN neutrino experiment.Comment: 5 pages, 1 figure. Presented at the Conference on the Intersections
of Particle and Nuclear Physics (CIPANP 2000), Quebec City, May 200
Updated Search for Electron Antineutrino Appearance at MiniBooNE
The MiniBooNE experiment at Fermilab has updated its search for \nu_\mu-bar
-> \nu_e-bar oscillations with data collected through May 2011. This represents
a statistics increase of 52% over the result published in 2010. The data favor
LSND-like oscillations over a background-only hypothesis at the 91.1%
confidence level. While the new result remains equally consistent with LSND,
the compatibility with the background-only hypothesis is improved. An excess of
38.6 +- 18.5 \nu_e-like events below 475 MeV is observed, consistent with the
observation of such an excess in neutrino mode.Comment: 3 pages, 1 figure. Proceedings of the PANIC 11 conference, Cambridge,
Mass., July 2011 Corrected typographical error in Table
A cryocooler for applications requiring low magnetic and mechanical interference
A very low-power, low-interference Stirling cryocooler is being developed based on principles and techniques described in several previous publications over the last four years. It differs in several important details from those built previously. It uses a tapered displacer based upon an analytical optimization procedure. The displacer is driven by an auxiliary piston and cylinder (rather than by mechanical linkage) using some of the working fluid itself to provide the driving force. This provides smooth, vibration-free motion, and, more importantly, allows complete mechanical and spatial separation of the cryostat from the pressure-wave generator. Either of two different pressure-wave generators can be used. One is a non-contaminating, unlubricated ceramic piston and cylinder. The other is a compressed-air-operated rubber diaphragm with motor-driven valves to cycle the pressure between appropriate limits
From an axiological standpoint
I maintain that intrinsic value is the fundamental concept of axiology. Many contemporary philosophers disagree; they say the proper object of value theory is final value. I examine three accounts of the nature of final value: the first claims that final value is nonāinstrumental value; the second claims that final value is the value a thing has as an end; the third claims that final value is ultimate or nonāderivative value. In each case, I argue that the concept of final value described is either identical with the classical notion of intrinsic value or is not a plausible candidate for the primary concept of axiology
A Single-armed Manta-board as a New Diver-controlled Planing Board and Its Use for Underwater Surveys
Due to inadequacies of previous underwater towing techniques and the special needs of a recent underwater survey, a modified mania-board technique was developed. With this new technique, the diver holds on to the manta-board with one arm; consequently, the board is referred to as a single-armed manta-board (sam-board). The sam-board proved inexpensive and highly maneuverable, allowing the divers to freely collect samples or record information. Through some experimenting with the board and changing some of the variables, such as rope lengths, towing speeds, etc., a highly efficient towing method can be achieved. Preplanning and strict diving safety procedures must, however, be implemented to assure efficiency. This paper presents the materials, guidelines for board construction, equipment, and preplanning and diving safety procedures necessary for the sam-board towing operation
An approach to optimization of low-power Stirling cryocoolers
A method for optimizing the design (shape of the displacer) of low power Stirling cryocoolers relative to the power required to operate the systems is described. A variational calculation which includes static conduction, shuttle and radiation losses, as well as regenerator inefficiency, was completed for coolers operating in the 300 K to 10 K range. While the calculations apply to tapered displacer machines, comparison of the results with stepped displacer cryocoolers indicates reasonable agreement
Polymer matrix and graphite fiber interface study
Hercules AS4 graphite fiber, unsized, or with EPON 828, PVA, or polysulfone sizing, was combined with three different polymer matrices. These included Hercules 3501-6 epoxy, Hercules 4001 bismaleimide, and Hexcel F155 rubber toughened epoxy. Unidirectional composites in all twelve combinations were fabricated and tested in transverse tension and axial compression. Quasi-isotropic laminates were tested in axial tension and compression, flexure, interlaminar shear, and tensile impact. All tests were conducted at both room temperature, dry and elevated temperature, and wet conditions. Single fiber pullout testing was also performed. Extensive scanning electron microphotographs of fracture surfaces are included, along with photographs of single fiber pullout failures. Analytical/experimental correlations are presented, based on the results of a finite element micromechanics analysis. Correlations between matrix type, fiber sizing, hygrothermal environment, and loading mode are presented. Results indicate that the various composite properties were only moderately influenced by the fiber sizings utilized
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