Study on fabrication of 3-D microstructures by synchrotron radiation based on pixels exposed lithography

We report research on the development of a method of fabricating three-dimensional microstructures that uses synchrotron radiation light. Some research on three-dimensional processing methods using SR lithography has already been reported. They have involved techniques of applying exposure energy distributions to resist surfaces. Complicated energy distributions need to be applied to resist surfaces to fabricate arbitrary three-dimensional structures. However, we devised a new method that made it possible to fabricate arbitrary three-dimensional microstructures by using a mask with pattern created function. The advantages of this method are that it is suitable for rapid prototyping and it reduces the fabrication time and cost since it is not necessary to fabricate conventional photolithographic masks. Our research involved a basic experiment on this method of fabrication where we succeeded in fabricating a free-form surface by exposing it through an overlapping array of pixels that created a single aperture. Moreover, the pixel size could be made smaller than the aperture size by overlapping adjoining pixels.     

New tetrapolar circuit method using magnetic field for measurementof local impedance change in biological substances

A new tetrapolar circuit method using a magnetic field is proposed to measure the local electric impedance change in living tissue. Based on this method, we designed an apparatus which can detect impedance changes in closely-situated two parts of living tissue, simultaneously and independently. Using this apparatus, we showed the effectiveness of the proposed method by an in vitro experiment and by an in vivo measurement of pulsatile waveforms in the forearm arteries. The detection sensitivity for a local impedance change was confirmed to be higher than that of the conventional tetrapolar method. Pulsatile impedance waveforms measured in the radial and the ulnar parts of the forearm were consistent with those estimated from the anatomical structure.     

Construction and field measurement of high-speed railway test embankment built on Indian expansive soil “Black Cotton Soil”

The railway embankment applied to high-speed railways is required to have high performance in terms of strength and deformation characteristics. Especially in the case of railway embankments that support slab tracks, the allowable settlement is very small. There are two technical challenges in constructing high-speed rail embankments to support slab tracks in India. The first challenge is dealing with problematic black cotton soil (BCS), which is widely distributed in India but very unusual soil in Japan. The second challenge is posed by the strict deformation requirement in the construction of the embankments. In this study, a 6 m-high test embankment was constructed on BCS in India. The deformation of the embankment and changes in water content were measured over a period of 18 months. In the construction of the test embankment, two different BCS countermeasures were applied. The results of the tests on this embankment were compared with those from an embankment without countermeasures. Complicated deformation behaviors, including settlement and the uplift of embankment, were observed in the section without countermeasure. However, in the embankment with cement-mixed gravelly soil (CGS) slab improvement with geosynthetics, the much lower amplitude of embankment deformation is evidence of the effectiveness of this countermeasure. The cohesive non-swelling soil (CNS) layer applied immediately below the embankment to reduce the water content fluctuation of BCS was not effective enough for use for high-speed railway embankment. Besides determining the technical challenges for the BCS countermeasures, the results of this study confirmed that a high-performance embankment can be constructed with Indian embankment material by performing sufficient compaction management.     

Negative Pore Air Pressure Generation in Backfill of Retaining Walls During Earthquakes and its Effect on Seismic Earth Pressure

In order to investigate the seismic behavior of conventional type and geosynthetic-reinforced soil retaining walls, 1-g model shaking tests were conducted. Model walls having a height of about 50 cm were placed on a subsoil layer and backfilled with a layer of dense dry Toyoura sand. They were subjected to several steps of horizontal irregular excitations. As a result, generation of negative pore air pressure in the backfill was observed. The maximum amplitude of the negative pore air pressure during each shaking step increased with the base acceleration. Based on analyses of the measured data, it was inferred that such negative pore air pressure was caused by outward wall displacement relative to the backfill and not by dilative behavior of the backfill. It would cause a reduction in the seismic earth pressures exerted from the backfill. This feature suggests an advantage of a rigid full-height facing for reinforced soil walls over the segmental types of facing. A simplified numerical procedure to evaluate earth pressure was applied while considering the effects of the negative pore air pressure, and it could qualitatively simulate the measured behavior in terms of the seismic earth pressure and the angle of failure plane in the backfill.     

Oxide ionic conductivities of apatite-type lanthanum silicates and germanates and their possibilities as an electrolyte of lower temperature operating SOFC

Electrical properties of La_xM₆O_12+1.5x (M = Si, Ge) as an electrolyte for solid oxide fuel cell (SOFC) have been investigated. In La_xSi₆O_12+1.5x and La_xGe₆O_12+1.5x of x = 8–11, the highest conductivities were achieved at x = 9.7 (La_9.7Si₆O_26.55) and x = 9.0 (La_9.0(GeO₄)₆O_1.5), respectively. The conductivity of La_9.0(GeO₄)₆O_1.5 was higher than that of La_9.7Si₆O_26.55 in a temperature region higher than 700 °C, and the conductivity (2.4 × 10⁻³ S cm⁻¹) of La_9.7Si₆O_26.55 at 400 °C was higher than that (8.3 × 10⁻⁵ S cm⁻¹) of La_9.0(GeO₄)₆O_1.5. The power densities of SOFC (H₂ | Pt | electrolyte (thickness: 1 mm) | Pt | O₂) using La_9.0(GeO₄)₆O_1.5 as an electrolyte were 14.3 mW cm⁻² (700 °C) and 24.0 mW cm⁻² (800 °C). The corresponding SOFC using La_9.7Si₆O_26.55 was found to work even at lower temperatures of 400 and 500 °C with power densities of 0.011 and 0.12 mW cm⁻². The SOFC (H₂ | Ni–Sm_0.2Ce_0.8O_1.9 | electrolyte | Ba_0.5Sr_0.5Co_0.8Fe_0.2O_2.5 | air) using 0.3 mm thickness La_9.7Si₆O_26.55 electrolyte gave the 3.4 mW cm⁻² power density at 500 °C.     

Effects of sea surface temperature accuracy on offshore wind resource assessment using a mesoscale model

Offshore wind simulations were performed with the Weather Research and Forecasting (WRF) model driven by three different sea surface temperature (SST) datasets for Japanese coastal waters to investigate the effect of the SST accuracies on offshore wind simulations. First, the National Centers for Environmental Prediction Final analysis (FNL) (1° × 1° grid resolution) and the Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) (0.05° × 0.05° grid resolution) datasets were compared with in situ measurements. The results show a decrease in accuracy of these datasets toward the coast from the open ocean. Aiming at an improved accuracy of SST data, we developed a new high‐resolution SST dataset (0.02° × 0.02° grid resolution). The new dataset referred to as MOSST is based on the Moderate Resolution Imaging Spectroradiometer (MODIS) product, provided by the Japan Aerospace Exploration Agency (JAXA). MOSST was confirmed to be more accurate than FNL and OSTIA for the coastal waters. Then, WRF simulations were carried out for 1 year with a 2 km grid resolution and by using the FNL, OSTIA and MOSST datasets. The use of the OSTIA dataset for a WRF simulation was found to improve the accuracy when compared with the FNL dataset, and further improvement was obtained when the MOSST dataset was applied. The sensitivity of wind speed and wind energy density to SST is also discussed. We conclude that the use of an accurate SST is a key factor not only for realistic offshore wind simulations near the surface but also for accurate wind resource assessments at the hub height of wind turbines. Copyright © 2014 John Wiley & Sons, Ltd.     

Microzonation for Seismic Geotechnical Hazards and Actual Damage During the 2005 Fukuoka-Ken Seiho-Oki Earthquake

The 2005 Fukuoka-ken Seiho-oki earthquake caused damage to structures due to liquefaction, slope failure and strong shaking in Fukuoka City. One of the authors had conducted microzonation for liquefaction, slope failure and strong shaking about 17 years before the earthquake. After the earthquake, the authors compared the zoning map with the actual damage. The results showed that liquefied sites coincided fairly well with predicted zones in the reclaimed lands. However, they were slightly different in a big sand spit named Uminonakamichi. Failure occurred at several slopes inside the predicted areas, while damage to buildings occurred due to strong shaking along the Kego Fault. The damaged area was slightly different from the predicted area. Furthermore, a liquefaction analysis was conducted and the results of this analysis were compared with the results of microzonation in 1988. In this paper, the authors discuss the validity of microzonation based on this comparison.