789 research outputs found
On the Neutrino Distributions in Phase Space for the Rotating Core-collapse Supernova Simulated with a Boltzmann-neutrino-radiation-hydrodynamics Code
With the Boltzmann-radiation-hydrodynamics code, which we have developed to
solve numerically the Boltzmann equations for neutrino transfer, the Newtonian
hydrodynamics equations, and the Newtonian self-gravity simultaneously and
consistently, we simulate the collapse of a rotating core of the progenitor
with a zero-age-main-sequence mass of and a shelluler rotation
of at the center. We pay particular attention in this
paper to the neutrino distribution in phase space, which is affected by the
rotation. By solving the Boltzmann equations directly, we can assess the
rotation-induced distortion of the angular distribution in momentum space,
which gives rise to the rotational component of the neutrino flux. We compare
the Eddington tensors calculated both from the raw data and from the M1-closure
approximation. We demonstrate that the Eddington tensor is determined by
complicated interplays of the fluid velocity and the neutrino interactions and
that the M1-closure, which assumes that the Eddington factor is determined by
the flux factor, fails to fully capture this aspect, especially in the vicinity
of the shock. We find that the error in the Eddington factor reaches in our simulation. This is due not to the resolution but to the different
dependence of the Eddington and flux factors on the angular profile of the
neutrino distribution function, and hence modification to the closure relation
is needed.Comment: 24 pages, 23 figures, 0 explosion, published in Ap
カンナイ オ リュウドウ スル キュウゲンアツ キエキ ニソウリュウ ノ ケンキュウ
This paper describes a new hybrid vibration suppression technique for flexible structures like beams and plates using piezoelectric elements and analog circuits. There are two main methods to suppress vibration of flexible structures. One is active vibration control and the other is passive vibration suppression. The former is often effective but has a stability problem. While the latter avoids such instability, its controlling force is small. Hence, this paper is proposing a new hybrid vibration suppression method that is stable and effective. The optimum values of the circuit are determined by simple formulations derived by Two Fixed Points Method. The proposed method is verified by experiments that demonstrate that the hybrid method works better than conventional passive vibration suppression methods
Electronic structures of B-2p and C-2p of boron-doped diamond film by soft X-ray absorption and emission spectroscopy
X-ray absorption (XAS) and emission (XES) spectroscopy near B-K and C-K edges
have been performed on metallic (~1at%B, B-diamond) and semiconducting
(~0.1at%B and N, BN-diamond) doped-diamond films. Both B-K XAS and XES spectra
shows metallic partial density of state (PDOS) with the Fermi energy of 185.3
eV, and there is no apparent boron-concentration dependence in contrast to the
different electric property. In C-K XAS spectrum of B-diamond, the impurity
state ascribed to boron is clearly observed near the Fermi level. The Fermi
energy is found to be almost same with the top of the valence band of non-doped
diamond, E_V, 283.9 eV. C-K XAS of BN-diamond shows both the B-induced shallow
level and N-induced deep-and-broad levels as the in-gap states, in which the
shallow level is in good agreement with the activation energy (E_a=0.37 eV)
estimated from the temperature dependence of the conductivity, namely the
change in C-2p PDOS of impurity-induced metallization is directly observed. The
electric property of this diamond is mainly ascribed to the electronic
structure of C-2p near the Fermi level. The observed XES spectra are compared
with the DVX-alpha cluster calculation. The DVX-alpha result supports the
strong hybridization between B-2p and C-2p observed in XAS and XES spectra, and
suggests that the small amount of borons (<1at%) in diamond occupy the
substitutional site rather than interstitial site.Comment: submitted to Phys. Rev. B, 5 pages and 5 figure
Tubular structures in the hepatic nuclei of a patient with delta agent.
Liver biopsy specimens obtained from a 31-year-old female with delta-positive hepatitis were studied by routine electron microscopy. In several nuclei of hepatocytes, there were filamentous or microtubular structures 15 to 20 nm in diameter, in the vicinity of which, round particles, probably cross sections of tubular ones, were seen. In these nuclei, irregular granules approximately 20 to 30 nm in diameter were also found in clusters. However, cores of Dane particles were not found in such hepatocytes. These intranuclear microtubular structures may be associated with delta agent.</p
- …