نتایج جستجو برای: fast atom bombardment mass spectrometry

تعداد نتایج: 751792  

2009
Y.-H. Liu Q. H. Liu

The time-to-frequency-domain conversion is often required in many applications of the finite-difference time-domain (FDTD) method. This paper presents a new FDTD time-to-frequencydomain conversion algorithm based on the optimization of nonuniform fast Fourier transform (NUFFT) with several redundancy-reduction techniques. The proposed algorithm can perform the FDTD conversion at multiple desire...

2005
Masaharu Hoshi Satoru Endo Kenichi Tanaka Masayori Ishikawa Tore Straume Kazuhisa Komura Werner Rühm Eckehart Nolte Thomas Huber Yasuo Nagashima Hiroto Fukushima Tetsuji Imanaka

The neutron energy spectrum from the atomic bomb consisted of a range of energies from thermal to fast neutrons. Fast neutrons contribute a larger dose to the human body than lowenergy neutrons per unit flux. The evaluation of the fast neutron component has been performed based on analyses of P (>3 MeV) activity measured immediately after the Hiroshima bomb and Ni (>2 MeV), which has a much lon...

1997
Xian-He Sun Yu Zhuang

In this study, a compact finite-difference discretization is first developed for Helmholtz equations on rectangular domains. Special treatments, then, are introduced for Neumann and Neumann-Dirichlet boundary conditions to achieve accuracy and separability. Finally, a Fast Fourier Transform (FFT) based technique is used to yield a fast direct solver. Analytical and experimental results show thi...

2016
Robert H. Maschhoff Kyong H. Lee

The Fast Fourier Transform (FFT) technique has long been used for spectral analysis but it has not been fully exploited for data compression purposes. This paper presents the concept for compressing telemetry data using the FFT in such a manner that the time domain waveform can be recovered. The sampled time-domain data is transformed into the frequency-domain data and only the significant comp...

2013
David J Lawrence Patrick N Peplowski Thomas H Prettyman William C Feldman David Bazell David W Mittlefehldt Robert C Reedy Naoyuki Yamashita

Surface composition information from Vesta is reported using fast neutron data collected by the gamma ray and neutron detector on the Dawn spacecraft. After correcting for variations due to hydrogen, fast neutrons show a compositional dynamic range and spatial variability that is consistent with variations in average atomic mass from howardite, eucrite, and diogenite (HED) meteorites. These dat...

2000
N. Baltateanu

Fast neutron sources are designed and experimentally tested, based on optimized conversion targets and linear accelerator as electron suppliers. Both gamma radiation and fast neutron emissions are studied, establishing the most effective characteristics of the targets in terms of material, spatial dimensions, relative position of target and source, incident electron energy. A numerical procedur...

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