Proposed wide-band and low-drive-power electrooptic modulators

Novel methods for the wide-band and low-drive-power electrooptic modulators are proposed. This wide-band and low-drive-power performance is obtained by the utilization of relative electrical and optical delays. Both a lumped and a traveling-wave configuration are described.     

Aseismic study on the reactor vessel of a fast breeder reactor

This paper presents the results of a seismic study using an scale steel model and a scale plastic model which simulate the reactor vessel of a loop type Fast Breeder Reactor (FBR). The main purposes of this study are to confirm the structure/liquid interaction and the aseismic safety of the reactor vessel experimentally, and also to verify the validity of the seismic response analysis model of the prototype vessel.The characteristics of coupled vibration between the structure and liquid were clarified, and the approach of calculation model to aseismic design was worked out. And, the dip plate and other core internals were found to be effective in suppressing the liquid free surface oscillation.     

Statistical fracture theory for multiaxial stress states using weibull's three-parameter function

Assuming that Weibull's three-parameter uniaxial distribution function should be valid only in equi-triaxial tensile stress state, a new multiaxial distribution function having location parameters is formulated involving both effects of internal and surface cracks. Using this new distribution function, the ones in simple and equi-biaxial tensile stresses are derived, and some discussions are performed about fracture probability ratios and expected values of fracture stresses.     

On-site fabrication of ceramics films from solution precursors by ink-jet and spray assisted processes

Solution processing based on Ink-jet and spray technologies is one of low cost on-site ceramic patterns/films fabrication methods at moderate temperatures from precursor solutions. In the present study, we have used ink-jet and spray technologies to fabricate ceramic films of titania directly on glass substrates at 300–400^∘C. The precursor solution was prepared by dissolving Titanium tetraisopropoxide in appropriate solvents (water/ethanol and acetylacetone). A cleaned glass substrate was kept on a hot plate and heated it up to a predetermined temperature. Droplets of the precursor solution produced through a spray gun were traveled towards heated substrate with a atmospheric pressure. When the droplets hit on the heated substrate, precursor started to decompose, nucleate and grow into the TiO₂ film. The anatase pattern was directly obtained by ink-jet method at moderate temperatures.     

Projective Visual Hulls

This article presents a novel method for computing the visual hull of a solid bounded by a smooth surface and observed by a finite set of cameras. The visual hull is the intersection of the visual cones formed by back-projecting the silhouettes found in the corresponding images. We characterize its surface as a generalized polyhedron whose faces are visual cone patches; edges are intersection curves between two viewing cones; and vertices are frontier points where the intersection of two cones is singular, or intersection points where triples of cones meet. We use the mathematical framework of oriented projective differential geometry to develop an image-based algorithm for computing the visual hull. This algorithm works in a weakly calibrated setting–-that is, it only requires projective camera matrices or, equivalently, fundamental matrices for each pair of cameras. The promise of the proposed algorithm is demonstrated with experiments on several challenging data sets and a comparison to another state-of-the-art method.     

Advanced technical textile products

This article is situated to be successive to “Fibre materials for advanced technical textiles” in the series of “Advanced technical textiles” of Textile Progress. In the previous article, fiber materials used for advanced technical textiles are introduced. In this article, advanced technical textiles products are described according to the application fields of the fiber materials. Although this article does not cover all the end-uses, it contains major parts of advanced technical textile products, which include products for resources and environmental issues, for automobiles, for medical uses, for protective uses, for information technologies, for civil engineering and for electronics textiles.     

Modelling the effects of test conditions on the measured swelling pressure of compacted bentonite

In the current concept of repositories for radioactive waste disposal, compacted bentonite and bentonite-based materials with low hydraulic conductivity are being used as engineered barriers to inhibit the migration of radioactive nuclides. To ensure low hydraulic conductivity, the swelling characteristics of compacted bentonite are also important. However, previous studies have shown that swelling pressure measurements vary considerably and that this variation may be attributable to the differences in testing apparatuses. This variability increases the uncertainty in the design of the facilities. Thus, in this study, an improved stress–strain model for bentonite materials during the saturation process is proposed. The validity of the model is confirmed by comparing the experimental results obtained using several test methods with the simulated results from the model. Consequently, it is found that the swelling pressure test results of compacted bentonite, which are affected by several factors, such as the stiffness of the test cell, the height of the specimen, and the initial degree of saturation, can be numerically simulated using the proposed model. Thus, the effects of these factors on the test results can be evaluated quantitatively using the proposed model.     

Highly sensitive detection of net hydrogen charged into austenitic stainless steel with secondary ion mass spectrometry

Secondary ion mass spectrometry (SIMS) is used to detect local distributions of hydrogen in various materials. However, it has been well-known that it is extremely difficult to analyze net hydrogen (H(N)) in metals with SIMS. This was because hydrogen, which is originated from moisture (H(2)O), hydrocarbon (C(x)H(y)) or other organic materials (C(x)H(y)O(z)) existing on a sample surface or in the SIMS chamber, is simultaneously detected in the SIMS measurement of the H(N), and the H(N) and the background-originated hydrogen (H(BG)) cannot be distinguished in a SIMS profile. The effective method for reductions and determinations of the H(BG) in hydrogen measurements of metallic materials with the SIMS method has not been established. The present paper shows an effective method for reduction and estimation of H(BG) in SIMS analyses of hydrogen charged into type 316 L austenitic stainless steel, and an accurate estimation method of the net charged hydrogen. In this research, a silicon wafer is sputtered by a primary ion beam of a SIMS near an analyzed area (silicon sputtering method) to reduce H(BG). An uncharged type 316 L sample was prepared for estimation of H(BG) in SIMS measurements of the hydrogen-charged sample. The gross intensities of hydrogen between the hydrogen-charged sample and the uncharged sample were compared. The gross intensities of hydrogen of the uncharged sample (26.8-74.5 cps) were much lower than the minimal gross intensities of hydrogen of the hydrogen-charged sample (462-1140 cps). Thus, we could reduce the H(BG) enough to estimate the hydrogen charged into the type 316 L sample. Moreover, we developed a method to determine intensities of H(BG) in the measurement of the hydrogen-charged sample by estimating the time-variation of hydrogen intensities in the measurements of the uncharged sample. The intensities of the charged hydrogen can be obtained by subtracting the estimated intensities of the H(BG) from the gross intensities of hydrogen of the hydrogen-charged sample. The silicon sputtering method used to reduce H(BG) and the determination method for H(BG) in this research can be applied to the accurate hydrogen analysis for other various metallic materials.