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2001年03月29日(木) [n年日記]

#1 [LDP] 3/29 の updates

#2 [labo] APS March Meeting - MgB2 Post deadline session

講演が RealAudio で収録されている。すごいな。

#3 [linux] mh has been orphaned

まあ誰かが take over してくれるじゃろ、と楽観(^^;

#4 [linux] sid's xlib 4.0.2-12 conflicts with jgroff?

% sudo apt-get upgrade
Reading Package Lists... Done
Building Dependency Tree... Done
1 packages upgraded, 0 newly installed, 0 to remove and 2  not upgraded.
Need to get 0B/1170kB of archives. After unpacking 0B will be used.
Do you want to continue? [Y/n]
(データベースを読み込んでいます... 現在 62021 個のファイルとディレクトリがインス
トールされています。)
xlibs 4.0.2-11 を(.../xlibs_4.0.2-12_i386.deb で)置換するための準備をしています.
..
xlibs を展開し、置換しています...
dpkg: /var/cache/apt/archives/xlibs_4.0.2-12_i386.deb の読み込みエラーです(--unp
ack) `/usr/X11R6/lib/X11/app-defaults'を上書きしようとしています。これはパッケー
ジ jgroff にも含まれています。。
以下のパッケージの処理中にエラーが発生しました:
 /var/cache/apt/archives/xlibs_4.0.2-12_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

違った:

sid ではもう jgroff は groff になってた。 potato から dist-upgrade したときになんか残骸が残ってたらしい。
dpkg --purge --force-depends jgroff
apt-get install jgroff
で jgroff の代わりに groff が入って一件落着。

いや:

apt-get install groff
だけでおっけーだった。

#5 [linux] Samba の LDAP 認証

PAM と組み合わせるとできるんでないかな、という気はしますですね。 このへん とか このへん とかかな?

しかし pam も ldap もよくわかっとらんのでアレ。

ということで:

apt-get install libpam-doc してみたり。 ldap はどっかに LC 2000 fall での鵜飼さんの講演記録があった記憶が... 有料だったからだめかな?

#6 [paper] JAP 89(7) 1 April 2001

Electric field in inductively coupled gas discharges:

R. Piejak, V. Godyak, and B. Alexandrovich; pp.3590-3593
The electric field in a low-pressure electrodeless discharge has been determined from discharge voltage measurements at constant discharge current as a function of gas pressure. Measurements have been made in neon, argon, and xenon at discharge currents of 1, 3, and 10 A with a driving frequency of 0.45 MHz. The behavior of the electric field as a function of gas pressure has been found to be qualitatively similar for all three gases. At the lowest gas pressures at which a discharge can be sustained, the electric field is relatively high. With increasing gas pressure the field reaches a local minimum, followed by a local maximum and another local minimum. Above 1 Torr, the electric field increases monotonically with gas pressure.

Practical scheme for three-dimensional simulation of electron cyclotron resonance plasma reactors:

Yasuyoshi Yasaka and Nobuki Uda; pp.3594-3601
A three-dimensional simulation code which calculates wave propagation, plasma transport, and gas phase chemical reactions self-consistently in an electron cyclotron resonance plasma reactor has been developed. The code is designed to treat the three-dimensional inhomogeneity with a reasonable accuracy in a realistic configuration of the reactor within an acceptable computational time using common computer resources. The profiles of electromagnetic wave fields and the temporal evolution of plasma parameters and radical densities in a bounded, inhomogeneous, cylindrical system have been calculated. The code can resolve azimuthal asymmetry of the plasma associated with a rectangular waveguide coupling or an asymmetric injection of reactive gases as well as the radial and axial variations.

Superhardness effects of heterostructure NbN/TaN nanostructured multilayers:

Junhua Xu, Masao Kamiko, Yaomin Zhou, Ryoichi Yamamoto, Geyang Li and Mingyuan Gu; pp. 3674-3678
Although superhardness effects have been extensively investigated for epitaxial ceramic nanomultilayer films with the same crystal structures in the last decade, those for multilayers with different crystal structures have been seldom studied. In this article, NbN/TaN nanomultilayers have been designed and deposited by reactive magnetron sputtering. The results showed that the crystal structures of NbN and TaN are face-centered cubic and hexagonal in superlattice films, respectively, and the lattice plane (111) of NbN is coherent with the (110) of TaN, i.e., {111}fcc-NbN{110}h-TaN. The results of microhardness measurement showed that the superhardness effects of NbN/TaN multilayers exist in a wide range of modulation period from 2.3 to 17.0 nm. This phenomenon is different from that of epitaxial ceramic multilayers where the maximum hardness usually takes place at a modulation period of 5.0?10.0 nm. It is proposed that the coherent stresses and the structural barriers (fcc/hexagonal) to dislocation motion between NbN and TaN layers are the main reasons for the high-hardness value in a wide range of modulation periods.

Design and characterization of thin film microcoolers:

Chris LaBounty, Ali Shakouri and John E. Bowers; pp. 4059-4064
Thin film coolers can provide large cooling power densities compared to bulk thermoelectrics due to the close spacing of hot and cold junctions. Important parameters in the design of such coolers are investigated theoretically and experimentally. A three-dimensional (3D) finite element simulator (ANSYS) is used to model self-consistently thermal and electrical properties of a complete device structure. The dominant three-dimensional thermal and electrical spreading resistances acquired from the 3D simulation are also used in a one-dimensional model (MATLAB) to obtain faster, less rigorous results. Heat conduction, Joule heating, thermoelectric and thermionic cooling are included in these models as well as nonideal effects such as contact resistance, finite thermal resistance of the substrate and the heat sink, and heat generation in the wire bonds. Simulations exhibit good agreement with experimental results from InGaAsP-based thin film thermionic emission coolers which have demonstrated maximum cooling of 1.15 ℃ at room temperature. With the nonideal effects minimized, simulations predict that single stage thin film coolers can provide up to 20-30 ℃ degrees centigrade cooling with cooling power densities of several 1000 W/cm^2.

Secondary electron emission yields from MgO deposited on carbon nanotubes:

Whikun Yi, et al.; pp. 4091-4095
Enormously high secondary electron emission yields under electric field are observed from MgO deposited on carbon nanotubes. The yields reach a value as high as 15 000 and are strongly dependent upon the bias voltage applied to the sample. The creation of the electric field across the MgO film after bombardment of primary electrons is considered as one of key features, since positive charges are generated at the surface by departure of secondary electrons. Subsequent bombarding electrons produce other secondary electrons inside the MgO film, then the liberated secondaries are accelerated towards the surface under the strong field. Under this condition, the secondary electrons gain sufficient energy to create further electrons by impact ionization. The process continues until an equilibrium avalanche is established. To elucidate the earlier explanations, the kinetic energy spectra of secondary electrons are measured by an energy analyzer at various bias voltages in MgO/carbon nanotube samples. The analysis of spectral results with the energy band diagram gives us strong evidence for the suggested mechanism.

Formation of β-C3N4 crystals at low temperature:

J. Wei; pp. 4099-4104
Carbon nitride films with β-C3N4 crystals of 200 nm grain size were grown on Si (100) substrates using magnetron sputtering. Reactive deposition was achieved using a graphite target in an argon/nitrogen plasma at room temperature. These films were characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy. Micro level β-C3N4 crystal grains were observed with TEM. According to calculations from electron diffraction pattern, these crystalline structures were in a good agreement with hypothetical b-C3N4 structure. AFM measurement also indicated the grain size was around 200 nm and the carbon nitride films had low surface roughness. From XPS data, maximum N/C ratio of 0.5 was achieved in the films. XPS spectra of the films typically showed three peaks in the C 1s core level spectrum (centered at 284.6, 285.9, and 287.2 eV) and two peaks in the N 1s core level spectrum (centered at 398.7 and 400.2 eV). This indicates that there are two types of C-N bonds; N is bonded to sp2- or sp3-coordinated C atoms in the as-deposited films. FTIR spectra showed three absorption bands in the range of 1000?3000 cm?1. The absorption band around 2367 cm?1 can be attributed to CN nitrile bond. The absorption bands around 1559 and 1201 cm?1 demonstrate the existence of CN (sp2) and C?N (sp3) bonds. Analysis of Raman spectrum further demonstrated the coexistence of sp, sp2, and sp3 bonds. All of XPS, FTIR, and Raman measurements showed the presence of fourfold coordinated β-C3N4 crystals in the films, which is in good agreement with TEM and electron diffraction results.

Sputtering and in-plane texture control during the deposition of MgO:

Liang Dong, Luis A. Zepeda-Ruiz and David J. Srolovitz; pp. 4105-4112
iMolecular dynamics simulations are performed to study the fundamental role of the ion beam in determining the in-plane texture of 100 oriented (out-of-plane) MgO films during ion beam assisted deposition (IBAD). Sputter yields are determined as a function of in-plane orientation for Ar ion beams. The minimum sputter yield exists at an ion beam orientation corresponding to the MgO 110 direction. The finite width of the sputter yield minimum is attributable to two main factors: (i) only a fraction of the incident ions are oriented to travel directly down the center of the channel and (ii) ions that are not exactly parallel to the channeling direction may channel. While the simulations imply that it is possible to in-plane orient {001} MgO films using IBAD, there are fundamental limitations on the degree of ordering that can be achieved.

#7 [labo] 科研費収支簿

提出。 フルウチの領収書は boss のポストに間違って入っていた。うぬぬ。

提出先で:

学部長に捕まって(わら、コーヒーをご馳走になった。
いろいろなところがいろいろ大変らしいなあ(謎

#8 [freshmeat] 3/28 分の新着メールから

#9 [linux] sarg

sid のパッケージになってたので、 potato でコンパイルしてインストールしてみた。 実に良い感じ。 squid の log analysis tool は数種類試してみたことがあるが、その中で best。

peer host からの query の exclude:

デフォルトだと ICP_QUERY をよこす sibling な squid ホストからの問合わせもログにカウントされてしまうが、 /etc/squid/sarg.users *1 にそのホスト名 (と IP アドレス) を書くと OK となった。

ちなみにこれらのファイルに空行を入れてしまうと、 あらゆる行にマッチしてログ出力が一切出なくなってしまう。

*1: なぜ sarg.hosts ではないのだろう...
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