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Compact laser-produced plasma sources have carved their niche in high-power terahertz generation, thanks to the intense work carried out by various research groups around the world. Solid targets are preferred as interaction medium due to their high electron density and ability to sustain strong currents and electric fields, thereby generating millijoule, broadband terahertz pulses with no known upper...
We report on the enhancement of the terahertz magnetic near-field which is realized by a tapered waveguide. A Tb3Ga5O12 crystal coupled with a double split-ring resonator was pumped by this tightly confined terahertz field, and the magnetic near-field was measured via the magneto-optic sampling. With the use of the tapered waveguide, the amplitude of the magnetic near-field is enhanced by about 2...
Terahertz (THz) magnetic field directly interacts with spin systems through Zeeman torque, enabling selective excitation of magnetic order dynamics. Here we demonstrate coherent THz-control of macroscopic magnetization in ErFeO3 using metamaterial-enhanced magnetic nearfields. We fluctuated initial process of laser-induced spin reorientation transition to modify the coherent path of phase transition,...
We propose a fast magnetic resonance imaging (MRI) technique based on compressed sensing. The main idea is to use a combination of full and compressed sensing. Full sensing is conducted for every several slices (F-slice) while compressed sensing with high compression rate is applied to the rest of slices (C-slice). We can perfectly reconstruct F-slice images, which are used to roughly estimate the...
Terahertz metamaterial technique enables a sophisticated electromagnetic excitation of materials. Here, we demonstrate resonant excitation of spin precession motion of canted antiferromagnet ErFeO3 using the magnetic near-field produced by split ring resonator (SRR). When the resonance frequency of spin precession was near the magnetic resonance mode of SRR, we observed substantial increase of precession...
We have evaluated the thermal and radiation degradation of flame-retardant ethylene-propylene rubber (EPR) insulators used for safety cables in nuclear power plants. Accelerated degradation of EPR sheets was conducted under conditions of (1) simultaneous thermal-radiation aging (100 °C and 1.0 kGy/h), (2) radiation aging (room temperature and 1.0 kGy/h), and (3) thermal aging (100 °C or 200 °C, and...
In previous paper, we described a novel deformation sensing technology using two conjugate multi-zeros optical beams for structure health monitoring. The multi-zeros beam has a phase term called the Gouy phase shift which is changing in proportion to the propagation distance, the initial beam waist size, and the order of the LG beam. We consider the effect of this phase term on the multi-zeros optical...
To clarify the deterioration mechanism of cables installed in nuclear power plants, three kinds of XLPE sheets with various antioxidant contents were aged by 100 Gy/h γ-ray irradiation at room temperature, 60, and 100°C. The remaining antioxidant content estimated from an oxidation induction time of a differential calorimetric thermogram as well as the elongation at break decreases faster as the initial...
As bandwidths of digital wireless communications get wider, it is essential to evaluate the I/Q imbalances among quadrature mixer ports in terms of the mismatch characteristics of the analog components in the I and Q paths and the carrier phase offset. This paper describes a technique to evaluate frequency-dependent I/Q imbalances and carrier phase offset in wideband quadrature mixers. Using an SSB...
Free volumes of six types of polyethylene with different densities and one type of cross-linked polyethylene were evaluated by the positron annihilation technique, and relationships between free volumes and material characteristics such as material density and mechanical characteristics were investigated. As a result, it was found that the estimated free volume radius and its number density decreased...
A novel method for imaging velocimetry of range motion distribution is proposed. It is based on what we call "moire Doppler effect" and temporal frequency estimation on each pixel. We project a grating pattern translating with a constant speed. Every point on the object illuminated by it returns a sinusoidally varying intensity, and is detected by the Correlation Image Sensor (CIS). In this...
In INSS2008, we described a new principle for monitoring full-axis (three translational and three rotational) deformation of large and long structures such as bridges, roads, and railways. It is based on a combined use of an optical Laguerre-Gaussian (LG) beam and correlation image sensor (CIS). In this paper, we describe theoretically and examine experimentally several key issues of this technology...
Micromachined directional microphones (sound source localization sensor) mimicking an auditory organ of Ormia Ochracea have been intensively studied based on center-supported, marginally free 1-D or 2-D diaphragm structures. Based on an exact mathematical formulation, a Gaussian weight function on the diaphragm is shown to be inevitable in the transduction of 1st and 2nd moments. An analysis was performed...
Micromachined directional microphones (sound source localization sensor) mimicking an auditory organ of Ormia ochracea have been intensively studied based on center-supported, marginally free 1-D or 2-D diaphragm structures. This paper first describes an exact mathematical theory of sound source localization based on the partial differential equation (PDE) formulation of the problem and the weighted...
The "water tree" is a degradation mode of power cable with polymer insulation. A water tree is composed of small droplets filled with water. As the conductivity in water tree is very high, it leads to dielectric breakdown when it grows up. Inside the water tree is filled with trap sites. Therefore, a water tree can be recognized as an electret.
Water tree is a degradation mode of power cable with polymeric insulation. A water tree is composed of small droplets filled with water. As the conductivity in water tree is very high, it leads to dielectric breakdown when it grows up. As inside the water tree is filled with trap sites, it is polarized with a certain distribution of relaxation time when a DC poling voltage is applied. Although its...
Two types of resin-coated papers were investigated; kraft papers and heat-resistant kraft papers partially covered with epoxy resin; those were laminated to some thickness. They were thermally degraded at 120degC for 240 to 1320 hours, and their mechanical strength, i.e. tensile strength was measured. The tensile strength of the resin-coated kraft paper decreased with the heating time and became smaller...
We deal with the problem of direction and distance estimate of emission sources in 3-D space. We first introduce a partial differential equation (PDE) what we call the location constraint PDE (LC-PDE), which provides a necessary and sufficient description of wavefield generated by a source at direction n and distance R. To remove differentials, we integrate the LC-PDE in a finite rectangular area...
In order to achieve high density and high performance package, through silicon vias (TSVs) technology has been desired. Our purpose is the development of silicon interposer which has TSVs and fine multilayer Cu wiring on both side. Since silicon substrate has a quite flat and smooth surface, it can be expected to form fine wiring such as global layer of device. Furthermore, silicon interposer can...
A novel silicon interposer (SilP) BGA package (PKG) - SilP PKG - has been developed and qualified through test chip. It features three key process technologies; Cu-filled through Si via (TSV), fine pitch multi-layer wiring with Cu- plating, and micro-bump interconnect. The cost-conscious fabrication process flow has been developed based on the build-up print boards' Cu-plating technology and Si wafer...
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