Damage Due to Spot Cavitation on Hemisperical Cylindrical Body (Comparison Between Isolated Cavity and Parallel Cavities)

When the Reynolds number is larger than the critical value or laminar separation is eliminated by a trip installed on a hemispherical cylindrical body, attached spot cavitation is observed occasionally. It occurs at fixed place in the vicinity of the minimum mean pressure and grows into a triangular wedge. In the present investigation, isolated and parallel spot cavitation is artificially generated on the hemispherical body adn the behavior of the cavitation is observed by instantaneous photographs. The frequency of damaging blows in the range of the flow speed of 25 to 50 m/s is obtained by counting the number of damaged pits on an aluminum specimen. When spot cavitation occurs adjacently, the cavity become rather stable. The pitting rate at the maximum damage zone by the parallel spot cavitation is much smaller than that by the isolated spot cavitation. The total pitting rates at the maximum damage zone by the isolated and parallel spot cavitation vary roughly 5th power of the flow speed for the both cases

Reflection of Metastable Atoms by a Glass Wall in a Positive Column Discharge Plasma

The leser-induced-fluorescence-spectroscopy (LIFS) method has been applied to a dc discharge plasma, and the radial density distribution of metastable ( 2 ¹S) helium atoms has been measured. It was found that the density did not tend to zero at the discharge tube wall. Rather, the density was about 20-30% of the value on the tube axis. By using the collisional-radiative model, we interpreted the result. As the origin of this finite population at the wall we considered two possibilities, namely, 1 ) the helium ions which recombine at the wall converted partly into the metastable atoms and 2 ) the metastable atoms were not quenched completely at the wall, but were reflected by a certain amount. We found that the first process could not reproduce the experimental population distribution, and that the second process with the reflection coefficient of the metastable atoms of 80-90% accounted for the experiment

Supersymmetry Breaking in a Large N Gauge Theory with Gravity Dual

We study phase structure of mass-deformed ABJM theory which is a three dimensional $\mathcal{N}=6$ superconformal theory deformed by mass parameters and has the gauge group $\text{U}(N)\times \text{U}(N)$ with Chern-Simons levels $(k,-k)$ which may have a gravity dual. We discuss that the mass deformed ABJM theory on $S^3$ breaks supersymmetry in a large-$N$ limit if the mass is larger than a critical value. To see some evidence for this conjecture, we compute the partition function exactly, and numerically by using the Monte Carlo Simulation for small $N$. We discover that the partition function has zeroes as a function of the mass deformation parameters if $N\ge k$, which supports the large-$N$ supersymmetry breaking. We also find a solution to the large-$N$ saddle point equations, where the free energy is consistent with the finite $N$ result.Comment: 42 pages, 11 figure

Numerical simulation of transfer and attenuation characteristics of soft-tissue conducted sound originating from vocal tract

A non-audible murmur (NAM), a very weak speech sound produced without vocal cord vibration, can be detected by a special NAM microphone attached to the neck, thereby providing a new speech communication tool for functional speech disorders as well as human-to-machine and human-to-human interfaces with inaudible voice input for use with unimpaired. The NAM microphone is a condenser microphone covered with soft-silicone impression material that provides good impedance matching with the soft tissues of the neck. Because higher-frequency components are suppressed severely, however, the NAM detected with this device can be insufficiently clear. To improve NAM clarity, the mechanism of NAM production as well as the transfer characteristics of the NAM in soft neck tissues must be clarified. We have investigated sound propagation from the vocal tract to the neck surface, using a finite difference time domain method and a head model based on magnetic resonance imaging scans. Numerical results show that, compared to air-conducted sound detected in front of a mouth, soft-tissue-conducted sound attenuates 50 dB at 1 kHz, which consists of 30 dB full-range attenuation due to air-to-soft-tissues transmission loss and -10 dB/octave spectral decay due to a propagation loss in soft tissues. The decay agrees well with the spectral characteristics of the measured NAM. (C) 2008 Elsevier Ltd. All rights reserved.ArticleAPPLIED ACOUSTICS. 70(3):469-472 (2009)journal articl

IMPACTS OF DRY SEASON AND FOREST FIRE 1997-1998 EPISODES ON MIXED DIPTEROCARP FOREST AT BUKIT BANGKIRAI, EAST KALIMANTAN [Pengaruh Musim Kering dan Kebakaran Hutan Episode 1997-1998 Terhadap Hutan Dipterocarp Campuran di Bukit Bangkirai, Kalimantan Timur]

Kawasan Kalimantan Timur mengalami musim kemarau panjang yang merangsang terjadinya kebakaran hutan yang luas pada 1982-1983 dan 1997-1998.Naskah ini mengemukakan hasil penelitian di Bukit Bangkirai, Kalimantan Tengah mengenai dampak dari kemarau panjang dan kebakaran hutan 1997-1998 terhadap diversitas tumbuhan pohon hutan dipterokarp campuran.Penelitian dilakukan dengan cara memperbandinkan hasil pencacahan tumbuhan pohon berlingkar batang setinggi dada lebih daripada 15cm yang terdapat dalam tiga petak penelitian, masing-masing: lha di hutan alam yang tidak terbakar (K-plot), 0,3 ha di hutan yang terbakar ringan (LD) dan lha di hutan yang terbakar berat (HD).Hasil penelitian menunjukkan bahwa musim kemarau panjang 1997-1998 menyebabkan 12,02% mortalitas individual pohon di hutan alam yang tidak terbakar, yang terlihat dari pohon mati berdiri tegak akibat kekeringan, atau kehilangan 21,67% dari total basal area. Secara keseluruhan terlihat bahwa kebakaran hutan menyebabkan kerusakan berat terhadap struktur dan komposisi hutan. Secara kumulatif, kemarau panjang dan kebakaran hutan menyebabkan mortalitas individual pohon berkisar 36-70% dan kehilangan total basal area antara 45-85% dan menyebabkan lantai hutan terbuka terhadap penyinaran matahari langsung karena menurunnya penutupan tajuk sebesar 23-79%.Kebakaran hutan juga berdampak terhadap penurunan biodiversitas tumbuhan pohon sebesar 23-79% pada tingkat jenis, 53-66% pada tingkat marga dan 18-21% pada tingkat suku.Tercatat perubahan komposisi jenis pada hutan yang terbakar; dominasi jenis Dipterocarpaceae dipetak hutan tak terbakar (K) menjadi dominasi pionir sekunder Macaranga gigantea-Vernonia arborea di petak terbakar berat (HD) dan dominasi Macaranga gigantea-Shorea smilhiana di petak terbakar ringan (LD).Beberapa jenis seperti Durio acutifolius dan Syzygium incarnaium mungkin dapat digolongkan sebagai jenis yang relative lebih tahan terhadap api

Mass deformed ABJM theory on three sphere in large N limit

In this paper the free energy of the mass deformed ABJM theory on S[3] in the large N limit is studied. We find a new solution of the large N saddle point equation which exists for an arbitrary value of the mass parameter, and compute the free energies for these solutions. We also show that the solution corresponding to an asymptotically AdS4 geometry is singular at a certain value of the mass parameter and does not exist over this critical value. It is not clear that what is the gravity dual of the mass deformed ABJM theory on S[3] for the mass parameter larger than the critical value

Psycho-physiological Studies for Attendance of the Persons with Wheelchairs (Second Report)

本報では，介助の実際を市街地において行った時の介助者―障害者間の生理心理的負担に ついて検討し，前報に引き続き安全で心地よい車いす介助のあり方を検討することを目的と する。 協力者は，前報同様，障害者４名，健常者10名である。 前報で示した形状の異なる車いすＡ，Ｂを用いた健常者同士（介助者及び介助協力者）の 介助と実際の障害者における介助で，大阪府立大学キャンパスの外周およそ3.5 km を車い すで押してもらった。 介助者，介助協力者及び障害者には，携帯用心拍記録装置を装着させ，介助中の心拍数を 記録した。また，介助前後には，STAI テストを測定した。 介助者の平均心拍数は，いずれの介助協力者の場合でも，車椅子Ａに比べて車椅子Ｂの方 が，高い値を示した。また介助時の心拍数，及び介助時間は，車椅子の形状及び介助協力者 によって，異なる結果を示した。介助前後の状態不安は，介助前に比べて介助後の方が低か った。 介助協力者の心拍数は，車椅子Ａ，Ｂ共に，いずれの協力者においても，介助中の心拍の 変動幅は少なく示された。しかし，協力者によっては，心拍数平均値からみて車椅子Ａより Ｂの方が低値を示した者や，逆に高値を示す者がおり，車椅子の機能や形状によって，介助 協力者の生理反応も異なることが示された。各介助協力者の状態不安は，車椅子Ａ，Ｂ共に 介助協力者間で異なる傾向を示した。 障害者を対象とした車椅子介助時における平均心拍数は，介助経験者に比べ未経験者の方 が有意(p0.05) に高かった。また，障害者の平均心拍数についても，未経験者介助時の方 が有意(p0.05) に高かった。 障害者を介助した時の介助者の状態不安は，介助経験者および未経験者共にいずれも介助 前に比べ介助後に減少し，介助経験による差は認められなかった。障害者の状態不安は，介 助未経験者による介助では介助後に増加し，介助経験者では，減少した。 以上のことから，身体障害者に対する介助経験の差が，介助者と身体障害者のいずれにも 生理心理的影響を及ぼすことが明らかとなった。今後の課題として，車椅子を押す簡単と思 われる介助についても，介助を受ける身体障害者の立場に立った視点での介助経験者の育成 が急務と考えられる。departmental bulletin pape