Development of thermal insulating material with low emissivity and high-temperature stability

In a previous study, we demonstrated that porous magnesium aluminate spinels, MgAl₂O₄, with two different pore size ranges (diameter = 0.05-1 μm and 1-5 μm) exhibited thermal conductivities of less than 0.3 W/(m K) in the high-temperature region of 1000°C-1500°C. In contrast, thermal insulating materials that are stable at even higher temperatures would offer further improved thermal efficiency and energy savings. Therefore, we investigated lanthanum hexaaluminate, LaAl₁₁O₁₈, with the expectation that its plate-like grain morphology would allow stable retention of its porosity at high temperatures. A process was developed for generating pores with the desired dimensions for use of the thermal insulating materials at high temperatures. The heat transfer behavior of these materials was evaluated via optical measurements. Herein, we report the structures and thermal properties of the obtained porous ceramics, including determination of the thermal emissivity measurements, to demonstrate their superior high-temperature thermal insulating properties.     

Structure and Characteristics of High‐Performance PMASynRM with Ferrite Magnets

Recently, the use of permanent magnet (PM) motors has risen markedly because of improvements in the performance of rare earth PM motors. However, the use of rare earth materials, which is an important aspect of the high‐performance PM motor, should be reduced because of the high cost and unpredictability associated with procuring such materials. The performance of motors that use rare earth materials has reached a very high level, one that will not be easy to match without such materials. In this paper, we propose a structure for a high‐power‐density PM‐assisted synchronous reluctance motor involving the use of a ferrite PM. The structure prevents irreversible demagnetization of the PM even in the presence of heavy flux‐weakening excitation or an inverter fault. It is shown that the proposed structure achieves high‐power and high‐efficiency performance. © 2014 Wiley Periodicals, Inc. Electr Eng Jpn, 187(1): 42–50, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22362     

The PV Era is coming — the way to GENESIS

Solar cells can surely be considered a critical technology for overcoming global environmental problems and energy problems. This paper will review the development background of solar cells, their current status and application technologies of solar cells. It will conclude with a discussion of the prospects of a future global-scale energy supply system based on solar cells.     

Intelligent AGV driving toward an autonomous decentralized manufacturing system

This paper proposes two methods that give intelligence to automatically guided vehicles (AGVs). In order to drive AGVs autonomously, two types of problems need to be overcome. They are the AGV navigation problem and collision avoidance problem. The first problem has been well known since 1980s. A new method based on the feature scene recognition and acquisition is proposed. The sparse distributed memory neural network (SDM) is employed for the scene recognition and acquisition. The navigation route for the AGV is learnt by use of Q-learning depending on the recognized and acquired scenes. The second problem is described as mutual understanding of behaviors between AGVs. The method of mutual understanding is proposed by the use of Q-learning. Those two methods are combined together for driving plural AGVs autonomously to deliver raw materials between machine tools in a factory. They are incorporated into the AGVs as the machine intelligence. In experimental simulations, it is verified that the first proposed method can guide the AGV to the suitable navigation and that the second method can acquire knowledge of mutual understanding of the AGVs’ behaviors.     

Silicon nanodot-array device with multiple gates

We fabricated a nanodot-array device with multiple input gates on a silicon-on-insulator (SOI) wafer by using a pattern-dependent oxidation method with multiple input gates, which embodies a new concept of a flexible single-electron device. Although the device can generate many logic functions owing to the capacitive coupling between dots and many gates, the complicated structural configuration makes it difficult to confirm the formation of the nanodot array. For further investigation of this kind of device to achieve higher functionality, it is important to demonstrate experimentally that the dot array is actually formed. We analyzed the oscillation-peak shift caused by the gate voltage change, and successfully determined the location of the dots that contributed to the experimentally observed oscillations.     

Combined use of a field-plate and narrow p-barriers for a wide-pitch ohmic-side readout of the BELLE double-sided SVD

We explored wide-pitch ohmic-side structures for the BELLE SVD, where we proposed a field-plate structure combined with narrow p-barriers in between the readout electrodes of 90, 113, 180, and 226 μm-pitch detectors. The effect of the p-barriers was studied with a numerical model to trace the carrier trajectories. The charge collection and sharing properties were examined in practice for prototype small-size detectors with an IR pulse shining from either the junction side or the ohmic side. The channel separation capabilities were also shown to be appropriate under nominal operation conditions.     

Effect of annealing on diamond-like carbon characteristics by electron spin resonance spectral analysis

We have examined the effect of annealing on physicochemical properties of the diamond-like carbon (DLC) films to produce higher quality films by the electron spin resonance spectral analyses of the immobilized dangling-bond sites (DBS), since amount of DBS reflects the characteristics of DLC films. On heat treatment of DLC deposited from ethylene monomer under anaerobic condition, the DBS decay was clearly shown, as the temperature raised. The decay described by second-order kinetics indicated that the recombination reaction of DBS progressed on heat treatment, suggesting that annealing treatment would accelerate the carbon-carbon covalent bonding network to produce harder films. In fact, the resulted DLC film derived from ethylene monomer showed non-existence of any type of oxygen atom based on X-ray photoelectron spectrum measurement, and water contact angle measurement showed higher hydrophobic surface of the DLC films.