Enhanced path smoothing based on conjugate gradient descent for firefighting robots in petrochemical complexes*

The firefighting robot system (FFRS) comprises several autonomous robots that can be deployed to fire disasters in petrochemical complexes. For autonomous navigation, the path planner should consider the robot constraints and characteristics. Specifically, three requirements should be satisfied for a path to be suitable for the FFRS. First, the path must satisfy the maximum curvature constraint. Second, it must be smooth for robots to easily execute the trajectory. Third, it must allow reaching the target location in a specific heading. We propose a path planner that provides smooth paths, satisfy the maximum curvature constraint, and allows a suitable robot heading. The path smoother is based on the conjugate gradient descent, and three approaches are proposed for this path planner to meet all the FFRS requirements. The effectiveness of these approaches is qualitatively and quantitatively evaluated by examining the generated paths. Finally, the path planner is applied to an actual robot to verify the suitability of the generated paths for the FFRS, and planning is applied to another type of robot to demonstrate the wide applicability of the proposed planner.     

Application of non-linear k–ω model to a turbulent flow inside a sharp U-bend

Simulation of the complex flow inside a sharp U-bend needs both refined turbulence models and higher order numerical discretization schemes. In the present study, a non-linear low-Reynolds number (low-Re) k–ω model including the cubic terms was employed to predict the turbulent flow through a square cross-sectioned U-bend with a sharp curvature, R _C/D = 0.65. In the turbulence model employed for the present study, the cubic terms are incorporated to represent the effect of extra strain-rates such as streamline curvature and three-dimensionality on both turbulence normal and shear stresses. In order to accurately predict such complex flowfields, a higher-order bounded interpolation scheme (Song et al., 1999) has been used to discretize all the transport equations. The calculated results by using both the non-linear k–ω model and the linear low-Reynolds number k–ɛ model (Launder and Sharma, 1974) have been compared with experimental data. It is shown that the present model produces satisfactory predictions of the flow development inside the sharp U-bend and well captures the characteristics of the turbulence anisotropy within the duct core region and wall sub-layer.     

Commercial ZrO2 paints as coatings for SiGe thermoelectric materials

The use of ZrO₂ paints to coat SiGe materials used in radioisotopic thermoelectric generators was studied. The best results were obtained when the SiGe alloys were double coated with a 200 h anneal at 1000° C after each coating. The thermoelectric properties of these coated samples were about the same as for the SiGe alloys coated by SiO₂ or Si₃N₄. The vapoursupression properties of the best ZrO₂ coatings fell between those of SiO₂ and Si₃N₄. In the SiGe doped with GaP alloys, the interface between the oxide coating and alloy is enriched with Ga₂O₃.     

A 0.18-μm 256-Mb DDR-SDRAM with low-cost post-mold tuning methodfor DLL replica

A 200-MHz double-data-rate synchronous-DRAM (DDR-SDRAM) was developed. The chip contains a delay-locked loop (DLL) which performs over a wide range of operating conditions. Post-mold-tuning allows precise replica programming. A 200-MHz intra-chip data bus is suitable for DDR operation     

Temperature measurements of polymer melts in the heating barrel during injection molding. Part 2: Three-dimensional temperature distribution in the reservoir

A new method has been developed to measure the three-dimensional temperature distribution of polymer melts in the reservoir of the heating barrel in the dynamic state. The procedure involves the use of a small-sheathed thermocouple in the nozzle of the machine. The tip of the thermocouple can be varied in depth from the surface to the center of the nozzle. The polymer melt of a shot is found to have a three-dimensional temperature distribution dependent on the geometry of the screw and the order of shot. These results reflect clearly the thermal histories of the polymer melt in the channel of the screw during plastication and conveyance, and indicate part of the dynamics of injection molding. Further, these measurements contribute to optimization of the design for the screw and the process conditions.     

Determination of dissolved natural thorium and uranium in Horonobe and Mizunami Underground Research Laboratory groundwater and its thermodynamic analysis

At two underground research laboratories situated at Horonobe and Mizunami, Japan, trace amounts of natural thorium and uranium dissolved in deep groundwater were investigated with the help of chemical pre-concentration method. The groundwater was sampled from underground boreholes under the geochemical condition of no atmospheric exposure, and the colloid contribution was checked by in situ two size-fractionated ultrafiltration systems. A rough decrease by half in the concentration after in situ filtration suggested the presence of natural colloids and suspended matter that were carriers of a portion of the elements. The Th and U concentrations in groundwater after 10 kDa filtration was evaluated as dissolved species, and was identified thermodynamically using existing hydrogeological and geochemical data, such as the mineral components in the groundwater at a given pH, ionic strength, concentration of co-existing ions, redox potential, and a hypothetical solubility-limiting solid phase. The crystalline solid phase of tetravalent thorium and uranium dioxides made the solubility very low compared with that of the amorphous phase.     

The characteristics of the external‐electrode mercury fluorescent lamp for backlighting liquid‐crystal‐television displays

Abstract— A reliable external‐electrode mercury fluorescent lamp (EEFL) has been developed for backlighting a liquid‐crystal‐television (LC‐TV) display. This involved the investigation of the EEFL characteristics and the improvement in the construction of the EEFL and drive waveforms, in the frequency range of 50–200 kHz, that affects the EEFL characteristics. The results showed that a sinusoidal waveform is suitable for driving the EEFL, and EEFL's voltage decreases when the frequency of the drive waveform is increased.     

Preparation of DNA-adsorbed TiO2 particles — Augmentation of performance for environmental purification by increasing DNA adsorption by external pH regulation

We have previously developed a novel photocatalyst, DNA-attached titanium dioxide (DNA-TiO₂), useful for the recovery and decomposition of chemicals [Suzuki et al. Environ. Sci. Technol. 42, 8076, 2008]. Chemicals accumulated in DNA near the surface of TiO₂ and were degraded under UV light. The efficiency of their removal was dependent on the amount of DNA adsorbed on TiO₂, indicating the attachment of larger amounts of DNA to result in higher efficiency. In this study, we succeeded in improving the performance of DNA-TiO₂ by increasing the amount of DNA adsorbed by regulating the external pH. The adsorption of DNA by TiO₂ dramatically increased at pH2, to about fourfold that at other pH values (pH4-10). Repeating the process of DNA addition increased the adsorption further. The attached DNA was stable on the surface of TiO₂ at pH2-10 and 4-56 °C, the same as DNA-TiO₂ prepared at pH7. As the DNA-TiO₂ prepared at pH2 retained much DNA on its surface, chemicals (methylene blue, ethidium bromide, etc.) which could intercalate or react with DNA were effectively removed from solutions. The photocatalytic degradation was slow at first, but the final degradation rate was higher than for non-adsorbed TiO₂ and DNA-TiO₂ prepared at pH7. These results indicated that preparation of DNA-TiO₂ at pH2 has advantages in that much DNA can be attached and large amounts of chemicals can be concentrated in the DNA, resulting in extensive decomposition under UV light.     

Carbon doping and etching in GaxIn1−xAsyP1−y on GaAs substrates using CBr4 by metalorganic chemical vapor deposition

Carbon doping and etching by CBr₄ were studied for Ga_xIn_1−xAs_yP_1−y (0≤y≤1) on GaAs grown by metalorganic chemical vapor deposition. It was found that the hole concentration drastically decreases with decreasing y when the flow rate of CBr₄ is constant. When y is under 0.5, the conduction type of GaInAsP changes ton-type. In the region of 0<y<0.6, the surface morphology was degraded and the carrier compensation became higher than could be estimated from the C concentration. This seems to be due to the micro defects because this range of composition is within the unstable region which is theoretically predicted. The etching effect by CBr₄ was observed during the growth. The rate of etching for InAsP component is about three times larger than that for the GaAsP component. The thermodynamic analysis suggests that the etching is due to the increase of the partial pressure of GaBr and InBr.     

A patient with psoriatic arthritis due to generalized pustular psoriasis (von Zumbusch type)

Pustular psoriasis is a rare skin disease that is observed in about 1% of all patients with psoriasis. We encounted a patient with psoriatic arthritis (PsA) due to pustular psoriasis. The patient was a 31-year old male. He visited our hospital due to generalized eruption and pain in multiple joints. Treatment was initiated under a diagnosis of psoriasis vulgaris and associated PsA. However, eruption extended to the entire body and became pustular, and fever developed. Since PsA symptoms were simultaneously aggravated, and body movements become difficult, he was admitted. A diagnosis of generalized pustular psoriasis (von Zumbusch) and associated symmetrical polyarthritis was made. Local therapy was performed. As systemic treatment, oral administration of an corticosteroid and weekly low-dose pulse methotrexate therapy were performed. The skin symptoms and PsA symptoms rapidly improved. At present, about one year after the initiation of treatment, the eruption almost completely disappeared, and joint pain does not present any problem in daily life.