なかのにっき

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• Advanced Bash-Scripting Guide

RC5・DESに続くdistributed.netの挑戦は、チェスでも素数でもなく「最短ゴロム定規（OGR)」でした。 まぁ例によって我々はクライアントプログラムを走らせるだけですが、OGRとは何か、どのようなアルゴリズムで探索しているのか…と言ったことを理解していれば、楽しさも増し、勧誘もし易くなるに違いありません。 そこで、まだ中途半端な内容ではありますが、今まで集めたOGRに関する情報をまとめてみます。

できてるんですけど、変な感じです。

どこにも鍵指定していないのに、HDD中の秘密鍵を探してきて
使っているようです。
同じディレクトリにはないのに...
sshd 側の log にも Accepted publickey と出ていますし、
ちゃんと使われているようです。
# そもそも publickey しか許可してないし。

しかも、○○ *1 は putty も使っていて、pagent にパスフレーズを
覚えさせていますが、そいつと通信しているようです。

というわけで、なにも設定していませんが、publickey を使って
パスフレーズ入力なしでログインできています。


動作の仕組みがわからないので気持ち悪くて使う気になりません。:-p

#!/bin/sh
for DIR in bin boot dev etc home lib opt root sbin tmp usr var
do
  mirrordir --no-netrc $* /$DIR /backup/$DIR
done

We investigate picosecond laser ablation of metals using a hybrid simulation scheme. Laser energy input into the electron system and heat conduction within it are modeled using a finite-difference scheme for solving the heat conduction equation. Atom motion in the near-surface part (72 nm) of the sample is modeled using molecular dynamics. Energy transfer between the electronic and atomic subsystems due to electron-phonon coupling is taken into account. For the special case of 0.5 ps UV laser irradiation of copper, we investigate the fluence dependence of the ablation yield, the temperature and pressure evolution in the target, and the ablation mechanism.

Recently, scanning tunneling microscopy results on the Brownian motion of two-dimensional vacancy islands on Ag(110) were presented. While the detachment of adatoms from the island and their diffusion on the terrace was permitted in the temperature range between 180 K and 220 K, the periphery diffusion of single adatoms was prohibited. The Brownian motion of the islands was found to follow a simple scaling law with terrace diffusion being the rate-limiting process. The scaling of the experimental results was confirmed by kinetic Monte Carlo (kMC) simulations. Here, we elaborate on the results and especially present a detailed derivation of the equation that relates the diffusivity of an anisotropic island to its size. Further details and results on the kMC simulations will be presented as well. Our results shed light on the recently discussed issue of attempt frequencies for surface diffusion. In this specific case of an anisotropic surface, we obtain prefactor ratios for exchange and hopping mechanisms.

The kinetics of diffusion-mediated smoothing of a TiO2 rutile (110) surface is studied over atomic length scales, by using a spot profile analysis of low-energy electron-diffraction data to characterize the morphology of the surface during thermal annealing. After the random removal of less than 1 ML of atoms by sputtering with an argon ion beam, the interface width and the distribution of terrace heights were found to stay nearly constant during annealing at 800 K, with terraces at just two heights making up 90% of the surface area over lateral distances of 400 Angstrom. Meanwhile, the coarsening of this nearly two-dimensional island structure is characterized by the growth of the average terrace width l from 20 to 60 Angstrom with annealing time, following l〜t^β with exponent β= 0.24±0.04. In addition, the stability of an 8% occupation of a third terrace height indicates negligible diffusion flux between layers during annealing. These results are compared with existing models for the microscopic dynamics involved.

In situ high-temperature (Ta = 1050-1250 K) scanning tunneling microscopy was used to determine the coarsening and decay kinetics of two-dimensional TiN adatom and vacancy islands on atomically smooth TiN(111) terraces. We report the first observation of an abrupt decrease in decay rates, irrespective of Ta, of adatom islands with areas less than a critical value of 1600 Angstrom^2. However, no decay rate transition was observed for vacancy islands. We attribute the size-dependent island decay behavior, which is consistent with detachment-limited kinetics, to anisotropic attachment and detachment barriers.

We have produced nanocrystalline titanium dioxide films with different structures (anatase or rutile) by depositing mass selected clusters from the gas phase. Nanoparticles are produced by a pulsed microplasma cluster source and are selected by aerodynamic separation effects. We have characterized nanocrystalline films by Raman spectromicroscopy and transmission electron microscopy, showing that the films assembled with very small clusters have a predominant rutile phase, whereas larger clusters form films with anatase structure. Our observations suggest that phonon confinement effects are responsible for a significant shift and broadening observed for the Raman peaks.

A comprehensive theoretical and experimental study of sputtering from copper surfaces roughened by low-energy Ar+ ion bombardment is reported. The total sputtering yields of thermally deposited Cu samples bombarded by 400-eV and 800-eV ions at 0°-70° angles of incidence have been measured and compared with a numerical model we have developed. To compute sputtering yields from rough surfaces, an original approach has been introduced, which accounts for sputtering anisotropy and shadowing of material emitted at grazing angles. The approach is flexible with respect to surface morphology and can be applied with any submicron structures. To specify the morphology that develops on the Cu surface under low-energy ion bombardment, the surface of bombarded Cu samples has been investigated by scanning electron microscopy. The morphology has been found highly unstable, appearing with random roughening, inclined conelike structures, ripples, or almost flat surfaces, depending on the bombardment conditions. For the samples considered it is found that the angular dependency of the total sputtering yield is strongly affected by surface morphology, which varies with the angle of ion incidence and bombardment energy. Approximations for accounting for the surface roughness required to describe sputtering at particular energy and angular regimes are discussed.