Temperature Effect on Hydrogen Generation by the Reaction of γ-Al2O3-Modified Al Powder with Distilled Water

The effect of temperature on the reaction of γ-Al₂O₃-modified Al powders with distilled water was investigated. It was found that by increasing the temperature up to 40°C, the hydrogen generation speed can be enhanced one to two orders of magnitude relative to that at room temperature (18°C). X-ray analyses and transmission electron microscopy observations revealed that the reaction by-product at 40°C is bayerite (Al(OH)₃), which is chemically neutral. The present results imply that slightly increasing the temperature is an effective way to get the target hydrogen generation speed.     

Test results of a catalytically assisted combustor for a gas turbine

A catalytically assisted ceramic combustor for a gas turbine was designed and tested to achieve low NO_x emissions. This combustor is composed of a burner and a ceramic liner. The burner consists of an annular preburner, six catalytic combustor segments and six premixing nozzles, which are arranged in parallel and alternately. In this combustor system, catalytic combustion temperature is controlled under 1000 °C, premixed gas is injected from the premixing nozzles to the catalytic combustion gas and lean premixed combustion over 1300 °C is carried out in the ceramic liner. This system was designed to avoid catalyst deactivation at high temperature and thermal shock fracture of the ceramic honeycomb monolith of the catalyst. A 1 MW class combustor was tested using LNG fuel. Firstly, NO_x emissions from the preburner were investigated under various pressure conditions. Secondly, two sets of honeycomb cell density catalysts and one set of thermally pretreated catalysts ware applied to the combustor, and combustion tests were carried out under various pressure conditions. As a result, it was found that the main source of NO_x was the preburner, and total NO_x emissions from the combustor were approximately 4 ppm (at 16% O₂) at an adiabatic combustion temperature of 1350 °C and combustor inlet pressure of 1.33 MPa.     

Optical interconnection using VCSELs and polymeric waveguidecircuits

We investigated the waveguide loss and transmission characteristics for optical interconnection using vertical-cavity surface-emitting lasers (VCSELs) and multimode polymeric waveguide circuits with crossings. The excess loss with 100 crossings is 2.2 dB when the image magnification from a VCSEL to a waveguide is 2.3. We obtained error-free (i.e., bit error rate <10^-11) optical interconnection at 1.0625 Gbps regardless of the number of crossings or the magnification. These results suggest the practicality of large-scale optical interconnection between VCSEL-based smart-pixel chips using multimode waveguides with more than 100 crossings     

Detection of water amount on the surface of glass fibers using thetransient leakage current of static electricity

A bundle of fibers (each 20 μm in diameter) was sandwiched by electrodes, and a high voltage of 400 V was supplied to the electrodes to measure the leakage current flowing on the surface of the fiber. The leakage current is as low as the order of mA. It was demonstrated that the current is almost linear relative to the water amount on the surface of the fibers in the examined range from 0.08 to 1.2% weight percent. This range is very important for the inspection of the fibers during the production stage in factories. A simple and practical instrument for detecting the amount of water is also presented     

Does product lifetime extension increase our income at the expense of energy consumption?

The present paper contributes to modeling a simple social accounting method with cumulative product lifetime distributions and argues how product lifetime extension affects income flow throughout the entire economic system. Empirical analysis focusing on automobile use (ordinary passenger vehicle, small passenger vehicle, and light passenger vehicle) in Japan revealed that if all of the additional income gain from product lifetime extension flows into the investment sector, a one-year lifetime extension during the ten years of the study period (1990–2000) would have led to an increase in income in 2000 amounting to + 7 billion yen, as well as contributing to savings in energy amounting to ? 4 × 10⁶ GJ. That is, longer-term passenger vehicle use increases income and decreases energy consumption under special cases. We also found that in the general case when less than 93% of additional income resulting from vehicle lifetime extension is directed to the investment sector, a + 1 year automobile lifetime extension increases income at the expense of energy consumption.     

Isochoric Specific Heat Capacity of Difluoromethane (R32) and a Mixture of 51.11 mass% Difluoromethane (R32) + 48.89 mass% Pentafluoroethane (R125)

The isochoric heat capacity (c _v ) of difluoromethane (R32) and a mixture of 51.11 mass% R32 + 48.89 mass% pentafluoroethane (R125) was measured at temperatures from 268 K to 328 K and at pressures up to 30 MPa. The reported density measurements are in the single-phase region and cover a range of ρ > 800 kg · m⁻³. The measured data are compared with results measured by other researchers. Also, the measured data are examined with available equations of state. As a result, it is found that the measured c _v ’s agree well with those of other researchers in the measurement range of the present study.     

Cooperative Understanding of Utterances and Gestures in a Dialogue-Based Problem Solving System

A dialogue plays an important role in learning how to solve a problem and form a concept. We are developing a problem solving and knowledge acquisition system based on co-reference between drill texts and dialogue with a teacher, focusing on first-grade mathematics. This paper presents a method of cooperative understanding of utterances and gestures within dialogue. We first describe our system design principles, which provide the basis for the integration of multimodal information during a dialogue. We define a principle of complementarity, explain its implementation, and describe the architecture of the problem solving system. We then show how to integrate our algorithms for utterance and gesture analysis within that software architecture. A feature-based approach is used for gesture recognition, derived from a sequence of images arising during the cooperative analysis of utterances. We conclude with an evaluation of the system against the design principles.     

Temperature‐frequency characteristics simulation of piezoelectric resonators and their equivalent circuits based on three‐dimensional finite element modelling

The electromechanical resonators made of piezoelectric crystals such as a quartz crystal are widely used for electronic devices. Their frequency–temperature characteristics are of primary importance for their applications to the frequency control devices. The present paper demonstrates numerical simulation for several types of resonators using 3‐D Finite Element Modelling. The results are compared with the theoretical values whenever they are available. As they are electronic devices, the equivalent circuit representation is often favourable for describing the admittance at the electrical terminals which enables the circuit analysis including the effect of the temperature change by using commercially available circuit simulators. Copyright © 2003 John Wiley & Sons, Ltd.     

Enhancing the thermal conductivity of polyacrylonitrile- and pitch-based carbon fibers by grafting carbon nanotubes on them

The thermal conductivities of ultrahigh tensile strength polyacrylonitrile (PAN)-based (T1000GB) and ultrahigh modulus pitch-based (K13D) carbon fibers with carbon nanotubes (CNTs) grown on them using chemical vapor deposition were measured using a thermal diffusivity meter. The thermal conductivities of the resulting hybrid materials were calculated to be 18.6 ± 1.7 and 965.6 ± 30.0 W/m K for T1000GB and K13D, respectively, while the respective original conductivities were 12.6 ± 1.0 and 745.5 ± 16.0 W/m K. The results clearly show that the CNTs grafting improves the thermal conductivities of both types of fiber.