3-D topology optimization of single-pole-type head by using design sensitivity analysis

It is necessary to develop a write head having a large recording field and small stray field in adjacent tracks and adjacent bits in perpendicular magnetic recording systems. In this paper, a practical three-dimensional topology optimization technique combined with the edge-based finite-element method is proposed. A technique for obtaining a smooth topology is also shown. The optimization of single-pole-type head having a magnetic shield is performed by using the topology optimization technique so that the leakage flux in the adjacent bit can be reduced. A useful shape of the magnetic shield obtained by the proposed technique is illustrated.</p

Compensation of Frequency-Dependent Attenuation for Tissue Harmonic Pulse Compression Imaging

Tissue harmonic imaging (THI) is highly effective for correct diagnosis. On the other hand, pulse compression is often used in a radar system and an ultrasound imaging system to perform high SNR measurement. Therefore, the performance of pulse compression of tissue harmonic imaging is required to be improved. The frequency-dependent attenuation (FDA) is a crucial problem in medical tissue imaging. In the pulse compression imaging, the deterioration of echoes by the FDA lowers the performance of a matched filtering using an ideal transmitted pulse as a template signal. Since, especially in the harmonic imaging, higher-frequency components are used for imaging than the fundamental imaging, the compensation of the FDA is strongly important for high-definition imaging. In this study, we examine a method to reduce the influence of the FDA on harmonics

New Panoramic View of 12^{12}CO and 1.1 mm Continuum Emission in the Orion A Molecular Cloud. I. Survey Overview and Possible External Triggers of Star Formation

We present new, wide and deep images in the 1.1 mm continuum and the $^{12}$CO ($J$=1-0) emission toward the northern part of the Orion A Giant Molecular Cloud (Orion-A GMC). The 1.1 mm data were taken with the AzTEC camera mounted on the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope in Chile, and the $^{12}$CO ($J$=1-0) data were with the 25 beam receiver (BEARS) on the NRO 45 m telescope in the On-The-Fly (OTF) mode. The present AzTEC observations are the widest (\timeform{1.D7} $\times$ \timeform{2.D3}, corresponding to 12 pc $\times$ 17 pc) and the highest-sensitivity ($\sim$9 mJy beam$^{-1}$) 1.1 mm dust-continuum imaging of the Orion-A GMC with an effective spatial resolution of $\sim$ 40\arcsec. The $^{12}$CO ($J$=1-0) image was taken over the northern \timeform{1D.2} \times\timeform{1D.2} (corresponding 9 pc $\times$ 9 pc) area with a sensitivity of 0.93 K in $T_{\rm MB}$, a velocity resolution of 1.0 km s$^{-1}$, and an effective spatial resolution of 21\arcsec. With these data, together with the MSX 8 $\mu$m, Spitzer 24 $\mu$m and the 2MASS data, we have investigated the detailed structure and kinematics of molecular gas associated with the Orion-A GMC and have found evidence for interactions between molecular clouds and the external forces that may trigger star formation. Two types of possible triggers were revealed; 1) Collision of the diffuse gas on the cloud surface, particularly at the eastern side of the OMC-2/3 region, and 2) Irradiation of UV on the pre-existing filaments and dense molecular cloud cores. Our wide-field and high-sensitivity imaging have provided the first comprehensive view of the potential sites of triggered star formation in the Orion-A GMC.Comment: 32 pages, 20 figures, accepted for publication in PAS

The Subaru Deep Field Project: Lymanα\alpha Emitters at Redshift of 6.6

We present new results of a deep optical imaging survey using a narrowband filter ($NB921$) centered at $\lambda =$ 9196 \AA ~ together with $B$, $V$, $R$, $i^\prime$, and $z^\prime$ broadband filters in the sky area of the Subaru Deep Field which has been promoted as one of legacy programs of the 8.2m Subaru Telescope. We obtained a photometric sample of 58 Ly$\alpha$ emitter candidates at $z \approx$ 6.5 -- 6.6 among $\sim 180$ strong $NB921$-excess ($z^\prime - NB921 > 1.0$) objects together with a color criterion of $i^\prime - z^\prime > 1.3$. We then obtained optical spectra of 20 objects in our $NB921$-excess sample and identified at least nine Ly$\alpha$ emitters at $z \sim 6.5$ -- 6.6 including the two emitters reported by Kodaira et al. (2003). Since our Ly$\alpha$ emitter candidates are free from strong amplification of gravitational lensing, we are able to discuss their observational properties from a statistical point of view. Based on these new results, we obtain a lower limit of the star formation rate density of $\rho_{\rm SFR} \simeq 5.5 \times 10^{-4}$ $h_{0.7}$ $M_\odot$ yr$^{-1}$ Mpc$^{-3}$ at $z \approx 6.6$, being consistent with our previous estimate. We discuss the nature of star-formation activity in galaxies beyond $z=6$.Comment: 49 pages, 16 figures, PASJ, Vol. 57, No. 1, in pres

F チュウシン ハッコウ ノ ジバ ヘンカ ノ チョクセツ ソクテイ ニヨル チョウビサイ ソウゴ サヨウ シンゴウ ノ ケンシュツ

Without microwave and rf field, we have optically detected the hyperfine (hf) signal of F centers in KCl at 4 K in a magnetic field range below 3.1 kOe. The hf signals were observed by the magnetic field dependence of F center luminescence. The angle dependence of hf signals was observed precisely for the first time. We determined the hf constant of Cl nuclei at the fourth and eighth shells, and K nucleus at ninth shell for the relaxed excited state (RES). They may due to the 2 s-like wave function in the RES of the F center

アルカリハライドチュウ ノ F チュウシン ノ レイキ ジョウタイ ノ キョウメイ オヨビ ヒキョウメイホウ ニヨル コウガクテキ ケンシュツ

We have optically detected the electron-spin resonance of F center in the relaxed excited state (RES) from the changes observed in the magnetic circular polarization (MCP) under the condition of modulated circular polarization at the resonant microwave of 50 GHz. We have found a new ESR peak at g=1.995 for the slightly high concentration of F center. Under the non-resonant condition, that is without microwave and rf field, we have optically detected the hf signal. We have found three facts : (1) the hf signal intensity is decreased with an increase of the frequency of the modulation field superimposed on the static magnetic field ; (2) the spin-lattice relaxation time in the RES is an important factor for the occurrence of the hf signal ; (3) the hf signal intensity is independent of the excitation power, P, in the low power range. However, it is reduced with an increase in P of the high power pulse laser

ヒカリ ポンプ サレタ F チュウシン ノ ジキ エン ヘンコウ ブンキョクド ト スピン コンゴウ カテイ

The pumping photon energy E_ dependence of the net spin-mixing parameter ε_t and δ(1-2ε_) for KI, where ε_ is the spin-mixing parameter in the nonradiative relaxation process of pumping F center, are determined from the analysis of the magnetic circular polarization of F center emission observed. These experimental dependences are explained using the theoretical plots of ε_0 and δ as well as assuming the empirical E_ dependence of ε_. The ω dependence of the spin polarization is estimated using these spin mixing parameter

Picosecond Time-Resolved Linear Polarization Spectroscopy of the Blue-Green Photoluminescence in Vacuum-Annealed Porous Silicon

P(論文)departmental bulletin pape