Flight Model Performance of 640-GHz Superconductor–Insulator–Superconductor Mixers for JEM/SMILES Mission

Performances of 640-GHz Superconductor–Insulator–Superconductor (SIS) mixers developed for the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) mission are described. SMILES, launched in September 2009, is the first mission to observe atmosphere from space using superconducting mixers. Ground test performances of the SIS mixers show very flat gain and noise characteristics in their observation bands in compliance with the specifications required for SMILES.     

Corrosion characteristics of reduced activation ferritic steel, JLF-1 (8.92Cr–2W) in molten salts Flibe and Flinak

Static corrosion tests were performed in molten salts, LiF–BeF₂ (Flibe) and LiF–NaF–KF (Flinak), at 500 °C and 600 °C for 1000 h. The purpose is to investigate the corrosion characteristics of reduced activation ferritic steels, JLF-1 (8.92Cr–2W) in the fluids. The concentration of hydrogen fluoride (HF) in the fluids was measured by slurry pH titration method before and after the exposure. The HF concentration determined the fluoridation potential. The corrosion was mainly caused by dissolution of Fe and Cr into the fluids due to fluoridation and/or electrochemical corrosion. Carbon on the surface might be dissolved into the fluids due to the corrosion, and this resulted to the decrease of carbide on the surface. The corrosion depth of the JLF-1 specimen, which was obtained from the weight losses, was 0.637 μm in Flibe at 600 °C and 6.73 μm in Flinak at 600 °C.     

Treatment capability of an up-flow anammox column reactor using polyethylene sponge strips as biomass carrier

The feasibility of applying a polyethylene (PE) sponge as a biomass carrier in an anaerobic ammonium oxidation (anammox) reactor and its nitrogen removal performance were also investigated. Experiments were carried out in an up-flow column reactor with synthetic inorganic wastewater. Experimental results indicate that reactor containing PE sponge biomass carriers showed a high nitrogen removal capability and exhibited stable performance. In addition, the reactor with 8 strips PE sponge as biomass carrier exhibited greater adaptation capacity compared to that with 6 strips and could achieve a high TN removal rate within a very short period. The ratio of NO₂-N removal and NO₃-N production to NH₄-N removal for the reactor was 1.26:0.21. Furthermore, to investigate the bacterial composition of the mature community, 16S rRNA sequences were amplified by PCR and analyses were conducted using DNA databases. Results showed that a new kind of anammox microorganism (Kumadai-1) was the dominant species in the reactor when using PE sponge as a biomass carrier.     

F2 laser deposition of CdTe microcrystallites-dopedfluoropolymer thin films

Crystalline thin films of polytetrafluoroethylene (PTFE) were deposited by F₂ laser (157 nm) ablation in 200 mTorr Ar gas atmosphere. Combining this PTFE thin-film process with CdTe microcrystallites synthesis in sizes of 3-7 nm via KrF laser (248 nm) ablation, CdTe microcrystallites-doped PTFE thin films were fabricated. The X-ray photoemission spectra show that the main architecture of PTFE and CdTe are maintained in the doped films. CdTe microcrystallites doped in PTFE matrix show an absorption edge shift toward higher energy and a third-order optical nonlinearity, which are induced by the quantum size effect     

New GTO Current Source Inverter with Pulsewidth Modulation Control Techniques

A new GTO current source inverter in which two auxiliary GTO's are added to the basic inverter circuit, which consists of six GTO's and three capacitors, is presented. One of the auxiliary GTO's is connected between the positive line of the inverter and the neutral of three Y-connected capacitors; another is connected between the negative line and the neutral. In the proposed inverter, the charges of three capacitors are controlled at the same time by means of pulsewidth modulation (PWM) to main GTO's and auxiliary GTO's. This inverter can supply both the sinusoidal current and voltage to the motor. The PWM control technique, the operating principle, and the experimental results for 2.2-kW induction motor drives are described. The output current waveform of this inverter is closely sinusoidal, as opposed to trapezoidal in the basic inverter circuit. The steady-state characteristics of the GTO-CSI induction motor drive system are analyzed by the state-variable methods, and a close agreement between the analyzed and the experimental results is obtained. Smooth and noiseless drive of induction motor over a wide range of speed is observed.     

Precise Measurements of the Vapor-Liquid Equilibria (VLE) of HFC-32/134a Mixtures Using a New Apparatus

A new apparatus for precise measurements of the vapor-liquid equilibria of mixtures by the circulation method has been developed. This apparatus has two special components: a high-stability temperature control system and a helium pressurization system. The temperature in the liquid bath surrounding the sample cell is kept constant within ±0.5mK. The helium pressurization system increases the pressure of the sampled mixture when measuring the compositions at low temperatures by gas chromatography. With these components, the uncertainty in measuring the vapor-liquid equilibria has been reduced. Using this apparatus, the vapor-liquid equilibria of HFC-32/134a mixtures were measured in a temperature range of 263.15 to 293.15K. These results are in good agreement with the calculated results from REFPROP (Ver. 6.01) with a relative pressure difference of about 2%.     

Characterization of the microbial community in an anaerobic ammonium-oxidizing biofilm cultured on a nonwoven biomass carrier

The enrichment and characterization of anaerobic ammonium-oxidizing biofilm cultures are ongoing in our laboratories. Biomass, with a predominately red color, demonstrating simultaneous removal of ammonium and nitrite under autotrophic and anoxic conditions, which is characteristic of anaerobic ammonium-oxidizing planctomycetes, was enriched and maintained for an extended period on a polyester nonwoven carrier. To investigate the bacterial composition of the mature biofilm community, 16S rDNA sequences were amplified by PCR and comparative analyses using DNA databases were conducted. Only one sequence had a notable similarity (92.2%) to that of the first discovered anaerobic ammonium-oxidizing planctomycete and lesser, yet significant, similarities to the 16S rDNA sequences of other recently reported anaerobic ammonium-oxidizing strains. The newly discovered strain (designated KSU-1) reported here was dominant among detectable members of the biofilm community. By fluorescence imaging, KSU-1 was shown to form spherical clusters wrapped in a thin layer of Zoogloea sp. Possible interactions and interdependencies of these two species are discussed with regard to the putative unculturability of the anaerobic ammonium-oxidizing planctomycetes.     

Development of a novel emitting vinyl polymer and its application in organic electroluminescent devices

Abstract— A novel emitting vinyl polymer, poly[4‐(7‐{4‐[N,N‐bis(9,9‐dimethylfluoren‐2‐yl)amino]phenyl}‐2,1,3‐benzothiadiazol‐4‐yl)phenylethylene] (PVFABT), was designed and synthesized. The new vinyl polymer was found to form smooth amorphous films with a high glass‐transition temperature of 199°C. The polymer possesses bipolar character with both electron‐donating and accepting properties. It undergoes reversible anodic oxidation and cathodic reduction to give stable cation and anion radicals. It exhibits intense orange fluorescence in solution and as film. A multilayer organic electroluminescent device using PVFABT as an emitting material emitted orange light, exhibiting high performance.     

Minimal design for human–agent communication

Robots have been envisaged as both workers and partners of humans from the earliest period in their history. Therefore, robots should become artificial entities that can socially interact with human beings in social communities. Recent advances in technology have added various functions to robots. The development of actuators and grippers show us infinite possibilities for factory automation, and robots can now walk and perform very smoothly. All of these functions have been developed as solutions for improving robot movement and performance. However, there are many remaining problems in the communication between robots and humans. Communication robots provide one approach to the realization of embodied interfaces. Furthermore, the unsolved problems of human–robot communication can be clarified by adopting the concept of subtractive methods. In this article, we consider the minimal design of robots from the viewpoint of designing communication. By minimal design, we mean eliminating the nonessential portions and keeping only the most fundamental functions. We expect that the simple and clean nature of minimally designed objects will allow humans to interact with these robots without becoming uninterested too quickly. By exploiting the fact that humans have “a natural dislike for the absence of reasoning,” artificial entities built according to minimal design principles can extract the human drive to relate with others. We propose a method of designing a robot that has “character” and is situated in a social context from the viewpoint of minimal design. This work was presented in part at the 10th International Symposium on Artificial Life and Robotics, Oita, Japan, February 4–6, 2005     

A study on the chromaticity shifts of blue phosphor for color plasma displays

The dependency of the chromaticity shifts on the concentration of Eu²⁺ doped in BaMgAl₁₀O₁₇ (BAM) was investigated under heat‐treatment and vacuum ultraviolet (VUV) irradiation. The Eu²⁺ ions in BAM show an asymmetrical broad emission band with a maximum at ～452 nm under excitation of VUV light at room temperature, showing that multiple crystalline cationic sites exist in the host. It was found that the chromaticity shifts greatly decrease with increasing heat‐treatment temperature. Regardless of the Eu²⁺ concentration, the chromaticity shifts caused by heat‐treatment are greater than that caused by VUV irradiation. Compared with conventional BAM, a solid solution of BAM with barium aluminate as a powder and film was also studied, and very few chromacity shifts were observed. It is suggested that the distribution of Eu²⁺ ions in different sites in a BAM lattice results in different chromaticity coordinates. By increasing the Eu²⁺ concentration in BAM, or under heat‐treatment and VUV irradiation, the emission band shifts towards longer wavelengths.