Difference in the detection limits of flaws in the depths of multi-layered and continuous aluminum plates using low-frequency eddy current testing

We examined the difference in the detection limits of flaws in the depths of multi-layered and continuous aluminum plates using low-frequency eddy current testing. The detection limits were measured by using a magneto-resistive sensor. Comparing the frequency of an applied magnetic field, the detection limit at 50 Hz is deeper than that at 1 kHz. Comparing the sample structure, the detection limit in the multi-layered samples is deeper than that in the continuous samples. These results are likely due to the differences in the skin depth and conductivity of the sample.     

A 2.5-GFLOPS, 6.5 million polygons per second, four-way VLIWgeometry processor with SIMD instructions and a software bypassmechanism

A four-way very long instruction word (VLIW), 312-MHz geometry processor with peripheral component interconnect/accelerated graphic port bus bridge was implemented in a 0.21-μm, 2.5-V, three-layer-metal CMOS process. We adopted (1) a software bypass mechanism, (2) single-instruction multiple-data stream instructions, (3) four sets of floating-point multiply add and accumulate execution units, (4) special condition code registers and a branch condition generator for a clipping operation, and (5) automatic clock delay tuning methodology. As a result of these features, we achieved a performance of 2.5 GFLOPS and 6.5 million polygons per second for a three-dimensional geometry processor, which is the highest published performance as a single geometry processor. The processor is applicable to computer-aided-design systems that require very high graphics performance     

Simulation of transverse crack formation on continuously cast peritectic medium carbon steel slabs

Reliable data are limited to the critical strain for the formation of transverse cracks on the slabs, owing to experimental difficulty to simulate temperature gradient in solidified shell in continuous casting mold. The present study is to determine the critical strain, ?_c, for the formation of transverse cracks on continuously cast slabs. A convenient and simple hot tensile test using rectangular test pieces with either V-notch or semi-circle notch or oscillation marks has been developed by placing the specimen under similar temperature gradient to that in solidified shell in the mold. The ?_c has been determined at a better accuracy and reproducibility, and the ?_c at a strain rate of 5?10^?4s^?1 is found to be a high 35% for test pieces without notch. It sharply decreases, however, to 10% for those with V- and semi-circle-notches, slightly decreases with increasing notch depth, and further decreases for those with oscillation marks that accompany solute segregation. Reduction of the oscillation mark depth is shown to be important measure to prevent the occurrence of transverse cracking of continuously cast slabs.     

Observation of metal on Si(0 0 1) by STM/STS and its consideration based on the first principles calculations

Local density of states (LDOS) is obtained by the first principles calculation based on the density functional theory on the Si(0 0 1)2 × 1 surface and on the surface with an Al dimer. At an Al dimer, LDOS has a high intensity in the conduction band region, which cannot be seen on the Si(0 0 1)2 × 1 surface. This tendency is observed in STS measurements as well. The possibility for a microelementary analysis is presented by applying this method to other metal atoms on the Si surface. Furthermore, it is pointed out that STS measurements should be always performed at the same tip-sample separation to obtain reproducible STS spectrums.     

220,000‐r/min, 2‐kW PM motor drive for turbocharger

This paper describes an ultrahigh‐speed permanent‐magnet synchronous motor drive, which is embedded in a turbocharger of an internal‐combustion engine. The electrical drive makes it possible to enhance output power of the turbocharger in a motoring mode and to retrieve combustion energy from exhaust gas in a regenerating mode. Computer simulations and experimental tests are conducted to examine various operation characteristics of a prototype. The experimental data demonstrate 220,000‐r/min operation at 2.2‐kW inverter output power, in good agreement with the simulation results and proving the feasibility of the proposed system. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(3): 31–40, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20408     

Short‐current pulse‐based adaptive maximum‐power‐point tracking for a photovoltaic power generation system

This paper focuses on a maximum‐power‐point tracking method of photovoltaics via use of the short‐current pulse. It has been reported that the optimum operating current is proportional to the short current and that maximum‐power‐point tracking can be performed by detecting the short current. The proposed method utilizes the intermittent short‐current pulse to estimate the optimum operating current and its operating characteristics have experimentally been verified. Also, an adaptive mechanism to identify the parameter between the optimum current and the short current is discussed. A prototype of the controller has been set up and the experimental results have demonstrated excellent performance, proving the feasibility of the system. © 2002 Scripta Technica, Electr Eng Jpn, 139(1): 65–72, 2002; DOI 10.1002/eej.1147     

Lasing band-edge identification for a surface-emitting photonic crystal laser

The possibility of single-mode oscillation over a large cavity area for photonic crystal lasers emitting at the photonic band edge has resulted in much interest in such materials for new forms of solid-state laser. In this paper, we measure the photonic bandstructure in our sample and identify the lasing band edge. By mapping out the bandstructure at the /spl Gamma/-point, we have observed fine structure at the band edge. The experimental results are in good agreement with the theoretically predicted bandstructure. Above threshold, we observe a lasing peak at 965 nm at one of the band edges. The far-field distribution of the laser is measured, showing an annular profile and azimuthal polarization. Calculations on the far-field distribution at the lasing band edge suggest the annular profile is due to an anti-symmetric resonant mode.     

Efficient hydrogen production using a multi-layered photobioreactor and a photosynthetic bacterium mutant with reduced pigment

A multi-layered photobioreactor (MLPR), where the light paths were formed by the localization of bacterial cells, was constructed for efficient hydrogen production. The performance was investigated under several conditions in order to clarify the effect of this reactor on hydrogen production. An analysis of the hydrogen production profile showed that the MPLR utilizes both the light that directly illuminates its surface and the light induced and diffused from its light paths for hydrogen production. It was also found that the hydrogen productivity in the MLPR was more than twice that in a plate-type reactor. When a photosynthetic bacterium mutant with reduced pigment, MTP4, was used, the maximum hydrogen production rate reached 2.0 l/m² h, which was 38% higher than that of a conventional plate-type reactor. The synergistic effect of the improvement in the reactor and the modification of the bacteria was brought about by the combination of the MLPR and MTP4, and resulted in an improvement in the hydrogen production.     

Long Preservation of AAV-Transduced Fluorescence by a Modified Organic Solvent-Based Clearing Method

The development of tissue clearing technologies allows 3D imaging of whole tissues and organs, especially in studies of the central nervous system innervated throughout the body. Although the three-dimensional imaging of solvent-cleared organs (3DISCO) method provides a powerful clearing capacity and high transparency, the rapid quenching of endogenous fluorescence and peroxide removal process decreases its practicability. This study provides a modified method named tDISCO to solve these limitations. The tDISCO protocol can preserve AAV-transduced endogenous EGFP fluorescence for months and achieve high transparency in a fast and simple clearing process. In addition to the brain, tDISCO was applied to other organs and even hard bone tissue. tDISCO also enabled us to visualize the long projection neurons and axons with high resolution. This method provides a fast and simple clearing protocol for 3D visualization of the AAV- transduced long projection neurons throughout the brain and spinal cord.     

Thermal conductivity of near-stoichiometric (U, Ce)C and (U, Pu, Ce)C solid solutions

The thermal conductivities of near-stoichiometric (U, Ce)C and (U, Pu, Ce)C solid solutions containing CeC up to 10 mol% were determined in the temperature range from 740 to 1600 K by the laser flash method. The thermal conductivity decreased with the cerium content in the solid solutions. The electrical resistivities were also measured for the purpose of analyzing the heat conduction mechanism. It was found that the decrease of electronic heat conduction caused by the addition of cerium resulted in decreasing the thermal conductivities of (U, Ce)C and (U, Pu, Ce)C compared with UC and (U, Pu)C.