Analysis of PD-generated SF/sub 6/ decomposition gases adsorbed on carbon nanotubes

Chemical byproducts analysis has been recognized as a powerful diagnosis method for SF₆ gas-insulated switchgear (GIS). The authors have previously demonstrated that a carbon nanotube (CNT) gas sensor could detect partial discharge (PD) generated in SF₆ gas. However, PD-generated decomposition gas species, which were responsible for the CNT gas sensor response, have not been identified yet. In this paper, two kinds of experiments were conducted in order to identify the responsible decomposition gas species. At first, the decomposition gas molecules adsorbed on CNTs were analyzed by Fourier transformation infrared (FTIR) spectroscopy. FTIR absorbance was observed around 735 cm^-1 after CNTs were exposed to PD generated in SF₆. In the second experiment, the CNT gas sensor responses to typical SF₆ decomposition products (HF and SF₄) were examined. The CNT gas sensor responded to these gases in the same way as to PD generated in SF₆. SF₄ response was larger than HF response. Based on these results, SF ₄ and SOF₂ emerged as candidates for the responsible decomposition gases. Electrochemical interactions between adsorbed gas molecules and CNT were discussed based on theoretical predictions of molecular orbital calculations. The calculation results suggested that both of SOF₂ and SF₄ could increase the CNT gas sensor conductance     

Posture Control for Personal Mobility Robot Using Feedback Compensation with Unstable Pole

This paper presents a novel posture control approach using feedback compensation with an unstable pole. For a narrow and small personal mobility robot (PMR), this is needed in order to control its posture for achieving quick turning and high acceleration. However, in the conventional control approach that uses the posture angle as a controlled variable, the zero moment point (ZMP) does not settle to the desired point in the following cases: an unknown disturbance force given to the PMR, a fluctuation in the center of gravity of the PMR, and a change in the conditions between the tires and the road surface. In this paper, a novel control method using feedback compensation with an unstable pole is proposed to achieve the desired ZMP in the steady state. The proposed controller changes the control input for the actuator of posture control to zero in order to achieve the desired posture angle. The effectiveness of the proposed approach is verified through experiments using a prototype of the PMR.     

Encapsulation-release property of amphiphilic hyperbranched d-glucan as a unimolecular reverse micelle

The synthesis of a novel unimolecular reverse micelle, the hyperbranched d-glucan carbamate (3), was accomplished through the carbamation reaction of the hyperbranched d-glucan (1) with the N-carbonyl l-leucine ethyl ester (2) in pyridine at 100 °C. Polymer 3 was soluble in a large variety of organic solvents, such as methanol, acetone, chloroform, and ethyl acetate, and insoluble in water, which remarkably differed from the solubility of 1. The degree of carbamate substitution (DS) for 3 was controlled by the feed rate of 2, and the DS values were in the range of 46.0-93.7%. Polymer 3 possessed the encapsulation ability for water-soluble molecules, such as rose bengal, thymol blue, and alizarin yellow in chloroform, and the encapsulation ability depended on the hydrophilicity of 3 and the molecular size of the dye. The rose bengal (RB) encapsulated polymer (RB/3) showed a slow release from the RB/3 system into water at neutral pH, while the release rate was significantly accelerated by the hydrolysis of the hydrophobic polymer shell under basic conditions.     

Determination of traction-separation laws on an acrylic adhesive under shear and tensile loading

Structural acrylic adhesives are of special interest because those adhesives are cured at room temperature and can be bonded to oily substrates. To use those adhesives widely for structural bonding, it is necessary to clarify the methodology for predicting strengths of bonding structures with those adhesives. Recently, cohesive zone models (CZMs) have been receiving intensive attentions for simulation of fracture strengths of adhesive joints, especially when bonded with ductile adhesives. The traction-separation laws under mode I and mode II loadings require to estimate fracture toughness of adhesively bonded joints. In this paper, the traction-separation laws of an acrylic adhesive in mode I and mode II were directly obtained from experiments using Arcan type adhesively bonded specimens. The traction-separation laws were determined by simultaneously recording the J-integral and the opening displacements in the directions normal and tangential to the adhesive layer, respectively.     

Abscopal Effect of Frozen Autograft Reconstruction Combined with an Immune Checkpoint Inhibitor Analyzed Using a Metastatic Bone Tumor Model

We evaluated the abscopal effect of re-implantation of liquid nitrogen-treated tumor-bearing bone grafts and the synergistic effect of anti-PD-1 (programmed death-1) therapy using a bone metastasis model, created by injecting MMT-060562 cells into the bilateral tibiae of 6–8-week-old female C3H mice. After 2 weeks, the lateral tumors were treated by excision, cryotreatment using liquid nitrogen, excision with anti-PD-1 treatment, and cryotreatment with anti-PD-1 treatment. Anti-mouse PD-1 4H2 was injected on days 1, 6, 12, and 18 post-treatment. The mice were euthanized after 3 weeks; the abscopal effect was evaluated by focusing on growth inhibition of the abscopal tumor. The re-implantation of frozen autografts significantly inhibited the growth of the remaining abscopal tumors. However, a more potent abscopal effect was observed in the anti-PD-1 antibody group. The number of CD8+ T cells infiltrating the abscopal tumor and tumor-specific interferon-γ (IFN-γ)-producing spleen cells increased in the liquid nitrogen-treated group compared with those in the excision group, with no significant difference. The number was significantly higher in the anti-PD-1 antibody-treated group than in the non-treated group. Overall, re-implantation of tumor-bearing frozen autograft has an abscopal effect on abscopal tumor growth, although re-implantation of liquid nitrogen-treated bone grafts did not induce a strong T-cell response or tumor-suppressive effect.     

Solvent extraction of niobium from alkali solution by methyltrioctylammonium chloride

Ｏｆｔｈｅｔｒａｄｉｔｉｏｎａｌｐｒｏｃｅｓｓｅｓｏｆｎｉｏｂｉｕｍｅｘｔｒａｃｔｉｏｎ ,ｔｈｅｈｙｄｒｏｆｌｕｏｒｉｃａｃｉｄｄｉｓｓｏｌｕｔｉｏｎ ｓｏｌｖｅｎｔ (ＭＩＢＫ ,ＴＢＰｅｔｃ .)ｅｘｔｒａｃｔｉｏｎｐｒｏｃｅｓｓｉｓｗｉｄｅｌｙｕｔｉｌｉｚｅｄ[1] .ＢｅｃａｕｓｅｏｆｓｐｅｃｉａｌｐｒｏｐｅｒｔｉｅｓｏｆＨＦ ,ｈｏｗｅｖｅｒ ,ｔｈｉｓｐｒｏｃｅｓｓｇｉｖｅｓｒｉｓｅｔｏｍａｎｙｓｅｒｉｏｕｓｐｒｏｂｌｅｍｓ ,ｆｏｒｅｘａｍｐｌｅ ,ｓｅｒｉｏｕｓｃｏｒｒｏｓｉｏｎｏｆｐｒｏｄｕｃｔｉ…     

Study on solubility of Nb2O5 in KOH solution and alkali leaching of niobite

Solubility of Nb₂O₅ and leaching behaviors of Nb and Ta from niobite in KOH solution have been investigated in order to develop an alkali hydrothermal leaching process of Nb and Ta. The solubility of Nb₂O₅ was measured in the range of 40 °C to 200 °C at various molar ratios of K₂O to Nb₂O₅(n(K₂O)/n(Nb₂O₅)). It has been found that Nb₂O₅ shows the maximum solubility at the solution composition of n(K₂O)/n(Nb₂O₅)=4/3 at a given temperature; the rise of temperature increases the solubility of Nb₂O₅ below 120 °C, but decreases it above 120 °C. The leaching behaviors of Nb and Ta were studied in the range of 150 °C to 250 °C and 0.1 MPa to 5 MPa. With the rise of temperature, the leaching degree increases when the leaching temperature is below 200 °C, but it decreases when the leaching temperature is above 200 °C. The maximum leaching degree is about 90% at 200 °C. It was proved that the alkali hydrothermal leaching process is effective for the recovery of Nb and Ta from niobite concentrate. Foundation item: The Key Project of Science and Technology Agency of Japan, 1994 Biography of the first author: ZHOU Kang-gen, doctor of engineering, professor, born in 1963, majoring in extractive metallurgy of rare metals and application of membrane separation technology.     

Augmented reality-based block piling game with superimposed collapse prediction

Understanding what cannot be seen is difficult. Physical behavior can be explained on the basis of physical theories even if the behavior cannot be observed. Explanation of what is physically happening in the real world would become easy, however, if annotations were superimposed on the real objects. Herein, the authors demonstrate how an understanding of a physical event can be facilitated by overlapping a real-world situation with a simulation that predicts a future state. This idea is demonstrated in a game application in which a player stacks blocks into a pile until it collapses. In general, it is easy to estimate whether a block on the edge of a table will fall or not. However, it is more difficult to predict whether a stack of many blocks will collapse, and in what manner the stack will collapse. Even though previous research has demonstrated that the problem of how two-dimensionally stacked blocks collapse can be reduced to solving a sequence of convex quadratic programs, algorithms for convex quadratic programs require massive computational resources. Hence, the authors developed a fast and new algorithm based on a linear program. The proposed algorithm realizes real-time simulation based on physics that superimposes predicted collapse. The block that is predicted to fall is superimposed on the real block with a lit background projection. The system was evaluated in an experiment, and superimposed augmented reality annotation was observed to be efficient. The system was also demonstrated in game contests and received positive feedback and comments.     

Autonomic load balancing of flow monitors

In monitoring flows at routers for flow analysis or deep packet inspection, the monitor calculates hash values from the flow ID of each packet arriving at the input port of the router. Therefore, the monitors must update the flow table at the transmission line rate, so high-speed and high-cost memory, such as SRAM, is used for the flow table. This requires the monitors to limit the monitoring target to just some of the flows. However, if the monitors randomly select the monitoring targets, multiple routers on the route will sometimes monitor the same flow, or no monitors will monitor a flow. To maximize the number of monitored flows in the entire network, the monitors must select the monitoring targets while maintaining a balanced load among them. We propose an autonomous load-balancing method where monitors exchange information on monitor load only with adjacent monitors. Numerical evaluations using the actual traffic matrix of Internet2 show that the proposed method improves the total monitored flow count by about 50% compared with that of independent sampling. Moreover, we evaluate the load-balancing effect on 36 backbone networks of commercial ISPs.