12,003 research outputs found
Strangeness Saturation: Dependence on System-Size, Centrality and Energy
The dependence of the strangeness saturation factor on the system size,
centrality and energy is studied in relativistic heavy-ion collisions.Comment: contribution for Proc. 19th Winter Workshop on Nuclear Dynamics,
Breckenridge, February 8-15, 200
Study of large adaptive arrays for space technology applications
The research in large adaptive antenna arrays for space technology applications is reported. Specifically two tasks were considered. The first was a system design study for accurate determination of the positions and the frequencies of sources radiating from the earth's surface that could be used for the rapid location of people or vehicles in distress. This system design study led to a nonrigid array about 8 km in size with means for locating the array element positions, receiving signals from the earth and determining the source locations and frequencies of the transmitting sources. It is concluded that this system design is feasible, and satisfies the desired objectives. The second task was an experiment to determine the largest earthbound array which could simulate a spaceborne experiment. It was determined that an 800 ft array would perform indistinguishably in both locations and it is estimated that one several times larger also would serve satisfactorily. In addition the power density spectrum of the phase difference fluctuations across a large array was measured. It was found that the spectrum falls off approximately as f to the minus 5/2 power
Evolution of induced axial magnetization in a two-component magnetized plasma
In this paper, the evolution of the induced axial magnetization due to the
propagation of an electromagnetic (em) wave along the static background
magnetic field in a two-component plasma has been investigated using the Block
equation. The evolution process induces a strong magnetic anisotropy in the
plasma medium, depending nonlinearly on the incident wave amplitude. This
induced magnetic anisotropy can modify the dispersion relation of the incident
em wave, which has been obtained in this paper. In the low frequency Alfven
wave limit, this dispersion relation shows that the resulting phase velocity of
the incident wave depends on the square of the incident wave amplitude and on
the static background magnetic field of plasma. The analytical results are in
well agreement with the numerically estimated values in solar corona and
sunspots.Comment: 7 pages, 1 figur
Densifying a Landfill for Commercial Development
This paper presents a case study of a dynamic compaction ( pounding ) project, undertaken in Skokie, Illinois. The purpose was to densify a 50-ft deep former municipal waste landfill for support of a one-story warehouse structure on shallow foundations. The majority of the pounding was performed utilizing a 15-ton weight falling from a height of 60 ft. In some areas, lower energy levels were used for surface compaction. All phases of the project are discussed, beginning with the subsurface exploration program and geotechnical analysis, through the experimental test pounding section, and the final check borings to observe that the production pounding was successful. A follow-up of the performance of the pounding, by monitoring foundation settlements, is discussed, as are topics such as depth of improvement, offsite vibrations, and energy input
Single polymer dynamics: coil-stretch transition in a random flow
By quantitative studies of statistics of polymer stretching in a random flow
and of a flow field we demonstrate that the stretching of polymer molecules in
a 3D random flow occurs rather sharply via the coil-stretch transition at the
value of the criterion close to theoretically predicted.Comment: 4 pages, 5 figure
Parametric Generation of Second Sound by First Sound in Superfluid Helium
We report the first experimental observation of parametric generation of
second sound (SS) by first sound (FS) in superfluid helium in a narrow
temperature range in the vicinity of . The temperature dependence
of the threshold FS amplitude is found to be in a good quantitative agreement
with the theory suggested long time ago and corrected for a finite geometry.
Strong amplitude fluctuations and two types of the SS spectra are observed
above the bifurcation. The latter effect is quantitatively explained by the
discreteness of the wave vector space and the strong temperature dependence of
the SS dissipation length.Comment: 4 pages, 4 postscript figures, REVTE
Building Design and Construction over Organic Soil
A lowrise office building was constructed on a mat foundation over a thick peat deposit that had been preconsolidated beneath surface fill. Environmental restrictions prevented use of deep foundations for fear that penetration through an aquaclude would permit contamination of a deeper water table. This paper describes the laboratory testing and field instrumentation programs, as well as the special geotechnical and structural analysis undertaken for the design and construction of this project. Included in the program were long-term consolidation tests, pressuremeter tests, use of heave markers, inclinometers and pore pressure piezometers. A site history was also developed to define the extent and nature of the surficial fill. To achieve much of the anticipated initial settlement, the basement was temporarily flooded, thus preloading with the full building weight. Water was removed as construction proceeded so that the full building weight was always maintained. Actual settlement was observed to agree fairly well with predicted settlements
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