Fabrication of room temperature-stable 12CaO · 7Al<Subscript>2</Subscript>O<Subscript>3</Subscript> electride: a review

12CaO · 7Al₂O₃ (C12A7) electride, which is synthesized by replacing free oxygen ions in cages with electron anions, has distinct advantages over electrides reported so far in respect of thermal and chemical stability and flexible preparation of various sample forms including single crystal, thin film, polycrystalline bulk and powder. These advantages, together with the fact that the concentration of the electron anions is controlled in a wide range according to a synthetic process, make the C12A7 electride attract growing attentions from both scientific and practical points of views. This paper reviews several chemical and physical synthetic processes of the C12A7 electride including thermal treatment of C12A7 under metal vapor and reducing gas atmospheres, hot Ar⁺ ion implantation, solidification of the strongly reduced C12A7 melt, and crystallization of the reduced glass in vacuum. Each process, having its own suitability for a specific form of the electride, has unique advantages such as a completeness of anion replacement, mass production capability and controllability of the electron-doped area. Electronic and optical properties of the resulting electrides prepared by the different process are briefly discussed in terms of the feature of the processes.     

Photovoltaic cell characteristics for high-intensity laser light

The series resistance value of a photovoltaic (PV) cell required for high-intensity light and the effects of both the α parameter (the ratio of the open-circuit voltage to the bandgap) and temperature on conversion efficiency are investigated by a calculation method derived from the fundamental characteristics of PV cell. The PV cell characteristics for high-intensity laser light, including Si, GaAs, InGaAs PV cells and InGaAs uni-traveling-carrier photodiode (UTC-PD), are experimentally investigated. The small series resistance as large as 20–30 μΩ cm² and the suppression of recombination are important for obtaining higher conversion efficiency, especially for high-intensity laser light.     

Tissue cooling and its effect on brightness temperatures by contact-type microwave applicators

Contact of an applicator on the skin surface may cool the tissues so that the resulting brightness temperature measured by the applicator is varied. The tissue cooling effect on the brightness temperature was quantitatively evaluated. From the experimental results, it was concluded that an accurate temperature control was needed in order to reduce the errors in the brightness temperature. A new method of temperature control which permits continuous measurement of the thermal responses of a human body was attempted, and advantages and disadvantages of the method are discussed. The research results may be practical and useful for the accurate measurement of brightness temperature.     

Excess heat evolution from nanocomposite samples under exposure to hydrogen isotope gases

Anomalous heat effect by interaction of hydrogen isotope gas and metal nanocomposites supported by zirconia or by silica has been examined. Observed absorption and heat evolution at RT were not too large to be explained by some chemical processes. At elevated temperatures of 200–300 °C, most samples with binary metal nanocomposites produced excess power of 3–24 W lasting for up to several weeks. The excess power was observed not only in the D-Pd·Ni system but also in the HPd·Ni system and HCu·Ni system, while single-element nanoparticle samples produced no excess power. The Pd/Ni ratio is one of the keys to increase the excess power. The maximum phase-averaged excess heat energy exceeded 270 keV/D, and the integrated excess heat energy reached 100 MJ/mol-M or 90 MJ/mol-H. It is impossible to attribute the excess heat energy to any chemical reaction; it is possibly due to radiation-free nuclear process.     

Sound shielding by a piezoelectric membrane and a negative capacitor with feedback control

The design and realization of an adaptive sound-shielding system based on a method to control the effective elastic stiffness of piezoelectric materials are presented in this paper. In this system, the sound-shielding effect is achieved by a sound reflection from the piezoelectric curved membrane fixed in rigid frame and connected to an active analog circuit that behaves as a negative capacitor. The acoustic transmission loss through the curved membrane was measured for the incident sound of frequency 1.6 kHz and of acoustic pressure level 80 dB. When the negative capacitor in the system was properly adjusted, the acoustic pressure level of the transmitted sound was reduced from the initial 60 dB to 15 dB by the action of the negative capacitor. Then the system was exposed to naturally changing operational conditions, and their effect on sound-shielding efficiency was studied. It is shown that the acoustic transmission loss of the system dropped by 35 dB within 30 min from the moment of negative capacitor adjustment. Therefore, a self-adjustment of the system has been implemented by appending an additional digital control circuit to the negative capacitor. It is shown that the aforementioned deteriorating effect has been eliminated by the adjusting action of the control circuit. The long-time sustainable value of 60 dB in the acoustic transmission loss of the adaptive sound shielding system has been achieved.     

采用热弹塑性有限元方法预测低碳钢钢管焊接变形

用有限元分析软件ABAQUS Code开发了用于模拟焊接温度场、焊接残余应力和焊接变形的热弹塑性有限元计算方法.通过建立三维有限元模型,预测了低碳钢钢管多层焊接时的温度场和焊接变形,并通过试验验证了所提出计算方法的精度和有效性.结果表明,在多层焊接条件下,采用有限元方法计算得到的焊接变形与试验结果十分吻合.