著者

Hasegawa K. Umemura M.

出版者

Wiley-Blackwell

雑誌

Monthly notices of the Royal Astronomical Society (ISSN:00358711)

巻号頁・発行日

vol.407, no.4, pp.2632-2644, 2010-10

被引用文献数

21 11

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We present a novel radiation hydrodynamics code, start, which is a smoothed particle hydrodynamics (SPH) scheme coupled with accelerated radiative transfer. The basic idea for the acceleration of radiative transfer is parallel to the tree algorithm that is hitherto used to speed up the gravitational force calculation in an N-body system. It is demonstrated that the radiative transfer calculations can be dramatically accelerated, where the computational time is scaled as Np log Ns for Np SPH particles and Ns radiation sources. Such acceleration allows us to readily include not only numerous sources but also scattering photons, even if the total number of radiation sources is comparable to that of SPH particles. Here, a test simulation is presented for a multiple source problem, where the results with start are compared to those with a radiation SPH code without tree-based acceleration. We find that the results agree well with each other if we set the tolerance parameter as θcrit≤ 1.0, and then it demonstrates that start can solve radiative transfer faster without reducing the accuracy. One of the important applications with start is to solve the transfer of diffuse ionizing photons, where each SPH particle is regarded as an emitter. To illustrate the competence of start, we simulate the shadowing effect by dense clumps around an ionizing source. As a result, it is found that the erosion of shadows by diffuse recombination photons can be solved. Such an effect is of great significance to reveal the cosmic reionization process.

著者

Tsukuda M. Abe S. Hasegawa K. Ninomiya T. Omura I.

出版者

Elsevier

雑誌

Microelectronics Reliability (ISSN:00262714)

巻号頁・発行日

vol.88-90, pp.482-485, 2018-09-30

被引用文献数

3

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In this paper, we propose the criteria of bias voltage from parasitic capacitance and demonstrate the criteria in an experiment with the present IGBT. The bias voltage criteria are theoretically predicted for the new generation IGBT based on the scaling principle. For safe switching, the required gate voltage bias is predicted to be −1.2V or less for the present IGBTs and −6V or less is required to completely cancel the gate noise voltage. From the IGBT design, the bias voltage of scaling IGBT requires −2V to completely cancel the gate noise voltage.