Superconducting State of the Two-Dimensional Superconductor α-(ET)2NH4Hg(SCN)4 Under the Magnetic Field Parallel to the Conducting Plane

The resistive transition to the superconducting (SC) state in -(ET)₂NH₄Hg(SCN)₄ was studied under magnetic fields applied parallel to the conducting plane. The SC state is divided into three regions: (1) temperature-dependent resistive region, (2) zero-resistive region, and (3) temperature-independent resistive region. We observed twofold symmetry in the resistance under an in-plane magnetic field near the midpoint of the SC transition, which indicates that the upper critical field ₀ H _c2 has the same twofold symmetry. This in-plane anisotropy can be ascribed to the crystal structure.     

Structural models of the photointermediates in the rhodopsin photocascade, lumirhodopsin, metarhodopsin I, and metarhodopsin II

Model building of the two photointermediates, lumirhodopsin and metarhodopsin I, and the activated form of rhodopsin, metarhodopsin II, is described. An outward swing of the C-terminal portion of transmembrane segment 3, pivoting on Cys110 at the N-terminal end of transmembrane segment 3, led to structural models of lumirhodopsin and metarhodopsin I. The conformation of the chromophore in the lumirhodopsin and metarhodopsin I models is controlled by the motion of transmembrane segment 3 and agreed closely with the hydrogen-bonding states of the protonated Schiff base in lumirhodopsin and metarhodopsin I as deduced from their FTIR and resonance Raman spectra and with the negative and positive CD bands of lumirhodopsin and metarhodopsin I, respectively. The structure of metarhodopsin II was constructed by an outward swing of transmembrane segment 3 and the rigid-body motion of transmembrane segment 6. The arrangement of the entire transmembrane segment of the metarhodopsin II model closely agreed with the electron paramagnetic resonance spectra of spin-labeled rhodopsin mutants and provided a structural basis for the protonation of Glu134, which is a key process in transducin activation.     

A method of gait coordination of hexapod robots using immune networks

Biological information processing systems can be regarded as one of the ultimate decentralized systems, and have been expected to provide various fruitful ideas in the engineering field. Among these systems, the immune system plays an important role in coping with dynamically changing environments by constructing self-nonself recognition networks among different species of antibodies, and has many interesting features from an engineering stand-point, such as learning, self-organizing abilities, and so on. However, it has not yet been applied to engineering fields. Therefore we pay close attention to the immune system and attempt to construct an artificial immune network for robot control. In this study we propose a new interpretation of the roles of antibodies in terms of self-assertion and subordination, and apply this idea to a gait coordination problem of a hexapod robot as a practical example. Several computer simulations are carried out, and the robustness against disturbances and the feasibility of our method are confirmed. This work was presented, in part, at the International Symposium on Artificial Life and Robotics, Oita, Japan, February 18–20, 1996     

Echo state networks with Tikhonov regularization: optimization using integral gain

This study proposes feed-forward echo state networks (ESN) as an estimator, and couples it with second-order proportional-integral-derivative (PID) feedback extension to compensate for dead time in feedback systems. The system is tested for two-dimensional space motion patterns recognition and prediction using simulations, which allows control of noise input. Tikhonov regularization is employed for training readouts and second-order PID feedback minimizes prediction bias. Evaluation is done using mean squared error and the coupled system performs well compared to any of its standalone versions. The results suggest it is feasible to (1) ‘compress’ the memory capacity of the system, and (2) reduce the number optimization parameters, while maintaining the estimation performance and following the excitation property of the estimator. It is feasible to optimize the ESN using feedback gain although it plays a significant role in the proposed system because the improvement by bias correction is far greater than that of optimization; thus, simplifying the estimation to a feedback problem which is easily tuned using the Ziegler–Nichols method.     

Competition between superconductivity and insulating magnetic state in κ-(BEDT-TTF)2Cu[N(CN)2]Cl: Effects of pressure, magnetic field, and partial anion substitution

Systematic experimental study of the electrical transport and static magnetization reveals a direct and delicate interplay between magnetism and superconductivity in the organic material-(BEDT-TTF)₂Cu[N(CN)₂]Cl, displayed through the specific temperature-pressure phase diagram, and such new effects for organic solids as the reentrant superconductivity in zero applied magnetic field and high-field-induced interchange between superconductivity and the nonmetallic resistive phase in the high-pressure region.     

A study on the use of tactile instructions for developing robot’s motions

Developing motions for humanoid robots is time consuming. However, sport and dance instructors can easily adjust their students?? postures by simple touches. This suggests the possibility of exploiting touch for motion development, and allows us to propose a methodology based on this concept. To realize such a system, it is required to define how the robot should interpret touches. We propose a supervised learning approach to cope with this issue, and verify its feasibility experimentally. We then study the data collected by the algorithm, and show that the system is practical both for motion development and for studying human-robot tactile communication. In particular, we present considerations on the sparsity that characterize the whole process and suggest how sparsity can be exploited for efficient interpretation of tactile instructions.     

Improvement of product strength and formability in stamping of Al–Mg–Si alloy sheets having bake hardenability by resistance heat and artificial aging treatments

Resistance heat and artificial aging treatments were introduced into a stamping operation to improve the product strength and formability of Al–Mg–Si alloy sheets having bake hardenability used for automobile body panels. In this treatment, the sheets undergo re-solution by resistance heat treatment, composed of resistance heating and water quenching just before the stamping. Stamped sheets are artificially aged just after the stamping to increase product strength. In the experiment, Al–0.60% Si–0.74% Mg alloy sheets were chosen as an example of Al–Mg–Si alloy sheets having bake hardenability. The re-solution solution treatment of the sheets was sufficiently accomplished by rapid resistance heat treatment, and formability of the sheets was improved. Hardness of the formed products was increased by artificial aging. It was found that the present process is effective in improving the product strength and formability of Al–Mg–Si alloy sheets having bake hardenability due to the compactness and rapidness.     

Starch Properties of New Sweet Potato Lines Having Low Pasting Temperature

Some new sweet potato lines were developed from progenies of a new cultivar, Quick Sweet, having a low pasting temperature. Starch granules from these lines demonstrated an abnormal morphology characterized by cracking into fragments. Starch and amylose contents were different among these lines. Pasting temperatures of these lines determined by the Rapid Visco Analyser were 53.8 to 66.6°C, i.e. 10 to 20°C lower than that of the control. Peak viscosities of some lines were similar to that of the control. Starch retrogradation, evaluated by percentage of leaked water and hardness of starch gels after cold storage, revealed that the control starch retrograded during storage for two to six weeks, but the starches of some lines retrograded much more slowly than the control starch and exhibited excellent cold storage stability. The pasting temperature had significant positive correlations with the percentage of leaked water and the hardness. These results indicate that Quick Sweet is a useful breeding material for improving pasting and retrogradation properties in sweet potato starch.     

CO hydrogenation over a rhodium vanadate catalyst: Reduction and regeneration of RhVO4 on SiO2

The hydrogenation of CO over an Rh vanadate (RhVO₄) catalyst supported on SiO₂ (RhVO₄/SiO₂) has been investigated after H₂ reduction at 500°C, and the results are compared with those of vanadia-promoted (V₂O₅–Rh/SiO₂) and unpromoted Rh/SiO₂ catalysts. The mean size of Rh particles, which were dispersed by the decomposition of RhVO₄ after the H₂ reduction, was smaller (41 Å) than those (91–101 Å) of V₂O₅–Rh/SiO₂ and Rh/SiO₂ catalysts. The RhVO₄/SiO₂ catalyst showed higher activity and selectivity to C₂ oxygenates than the unpromoted Rh/SiO₂ catalyst after the H₂ pretreatment. The CO conversion of the RhVO₄/SiO₂ catalyst was much higher than that of V₂O₅–Rh/SiO₂ catalyst, and the yield of C₂ oxygenates increased. We also found that the RhVO₄/SiO₂ catalyst can be regenerated by calcination or O₂ treatment at high temperature after the reaction.