Electrochemical polymerization of pyrrole in supercritical carbon dioxide-in-water emulsion

Supercritical carbon dioxide is an environmentally benign solvent but its low polarity limits electrochemical reactions in it. We now report the electrochemical polymerization of pyrrole in a supercritical carbon dioxide-in-water (C/W) emulsion in the presence of a surfactant. Black polypyrrole films were formed on Pt electrodes, whose conductivity was comparable with non-oriented polypyrrole prepared in conventional solvents. The structure of the polypyrrole films was confirmed by IR and Raman spectroscopic measurements. p-Toluenesulfonic acid was a suitable supporting electrolyte among the electrolytes examined for the electrochemical polymerization in the C/W emulsion. A typical nodular morphology was observed on the basis of the SEM and AFM measurements. Confocal scanning microscope revealed the formation of a fine uneven texture on the film prepared in the C/W emulsion.     

The Effect of Chemical Composition and Heat Treatment Conditions on Stacking Fault Energy for Fe-Cr-Ni Austenitic Stainless Steel

In order to establish more reliable formulae for calculating stacking fault energies (SFE) from the chemical compositions of austenitic stainless steels, SFE values were measured for 54 laboratory-melted heats and 2 commercial heats. The results were checked against those of a first-principle, atomistic calculation approach. More than ~20,000 data points for the width and angle of the Burgers vectors were determined from dark-field images of isolated extended dislocations in 56 heats of austenitic stainless steel using weak electron beams with g-3g diffraction conditions. Based on these numerous observations and on fundamental thermodynamic analyses, it is concluded that the SFE values for austenitic stainless steels are changed not only by chemical composition but also by heat treatment. In this paper, new formulae for calculating SFE values from the chemical compositions in three different heat treatment conditions have been proposed for austenitic stainless steels within given limited chemical composition ranges. In these formulae, the SFE values are calculated from the nickel, chromium, molybdenum, silicon, manganese, nitrogen, and carbon contents for the each heat treatment condition. The three heat treatment conditions studied were water cooling after solution heat treating (SHTWC), furnace cooling after solution heat treating, and aging after SHTWC.     

Paradigms representing the relationship between the inner of a brain and the outer world

Neuroscience was initially based on simple computer models, and the resulting assumption of blocks of information and step‐by‐step information processing disregards the dynamic features of living neuronal networks. Building semiartificial intelligence in a culture dish using a simple living neuronal network makes comparison with an engineering model easier than when analyzing a complicated brain network. We hypothesize that the status of the neuronal network changes autonomously according to both its own internal state and input from the outer world. Our investigation of such network suggests that an electrical stimulus can make the living neuronal network shift to a particular state, and the response pattern to each input is loosely coupled rather than strictly linked. The critical point we propose regarding brain‐like information processing is that the internal state of the autonomous neuronal network is modified by input from the outer world. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Visual control of autonomous mobile robot based on self-organizing model for pattern learning

This article proposes a self-organizing model for pattern learning together with an application to an autonomous mobile robot system. The self-organizing model consists of a processing rule prescribed and a memory part being blank at the initial stage. To an input signal, the model searches for a similar signal in the memory, and recalls its related information. If the information accompanied with the input signal differs from the recalled information, the model adds the new information to the memory. It influences the subsequent operations. Thus, the model constructs successively a data-base in a self-organizing way. This model can universally learn and reproduce any pattern of input-output response desired. Two principal functions in autonomous movement, i.e., position identification and obstacle avoiding movement were realized based on the self-organizing model. Furthermore, a camera type autonomous mobile robot system for indoor was made up. The size of the robot is about 0.7 × 0.7 × 0.7 m, and the weight is about 30 kg. The speed of movement is less than 3 km/h. A small computer that has a 16 bit microprocessor and a 1 Mbyte RAM controls the motion of the robot with an extended C language.     

Joint-space orthogonalization and passivity for physical interpretations of dextrous robot motions under geometric constraints

A principle of ‘joint-space orthogonalization’ is proposed as an extended notion of hybrid (force and position) control for robot manipulators under geometric constraints. The principle realizes the hybrid control in a strict sense by letting position feedback signals be orthogonal in joint space to the contact force vector whose components exert at corresponding joints. This orthogonalization is executed via a projection matrix computed in real-time from a Jacobian matrix of the constraint equation in joint coordinates. To show the important role of the principle in control of robot manipulators, two basic set-point control problems are analysed. One is a hybrid PID control problem for robot manipulators under geometric endpoint constraint and another is a coordinated control problem of two arms. It is shown that passivity properties of residual dynamics of robots follow from the introduction of a quasi-natural potential and the joint-space orthogonalization. Various stability problems of PID-type feedback control schemes without compensating for the gravity force and with or without use of a force sensor are discussed from passivity properties of robot dynamics with the aid of the hyper-stability theory.     

Microstructural Development of Natural Hydroxyapatite Originated from Fish-Bone Waste through Heat Treatment

The morphologic and microstructural development of natural fish bone through heat treatment is examined in view of fish-waste management and as a possible route for hydroxyapatite ceramics. Fish bone heated at temperatures ≤1300°C maintains a porous structure, with a sintered wall and a major crystalline phase of hydroxyapatite. Fish-originated ceramics are potentially useful as bioactive media as well as for environmentally compatible materials.     

Hydride Anion Substitution Boosts Thermoelectric Performance of Polycrystalline SrTiO3 via Simultaneous Realization of Reduced Thermal Conductivity and High Electronic Conductivity

The development of environmentally benign thermoelectric materials with high energy conversion efficiency (ZT) continues to be a long-standing challenge. So far, high ZT has been achieved using heavy elements to reduce lattice thermal conductivity (κ_lat). However, it is not preferred to use such elements because of their environmental load and high material cost. Here a new approach utilizing hydride anion (H⁻) substitution to oxide ion is proposed for ZT enhancement in thermoelectric oxide SrTiO₃ bulk polycrystals. Light element H⁻ substitution largely reduces κ_lat from 8.2 W/(mK) of SrTiO₃ to 3.5 W/(mK) for SrTiO_3−xH_x with x = 0.216. The mass difference effect on phonon scattering is small in the SrTiO_3−xH_x, while local structure distortion arising from the distributed Ti−(O,H) bond lengths strongly enhances phonon scattering. The polycrystalline SrTiO_3−xH_x shows high electronic conductivity comparable to La-doped SrTiO₃ single crystal because the H⁻ substitution does not form a grain boundary potential barrier and thus suppresses electron scattering. As a consequence, SrTiO_3−xH_x bulk exhibits maximum ZT = 0.11 at room temperature and the ZT value increases continuously up to 0.22 at T = 657 K. The H⁻ substitution idea offers a new approach for ZT enhancement in thermoelectric materials without utilizing heavy elements.     

Coalition structure generation in cooperative games with compact representations

This paper presents a new way of formalizing the coalition structure generation problem (CSG) so that we can apply constraint optimization techniques to it. Forming effective coalitions is a major research challenge in AI and multi-agent systems. CSG involves partitioning a set of agents into coalitions to maximize social surplus. Traditionally, the input of the CSG problem is a black-box function called a characteristic function, which takes a coalition as input and returns the value of the coalition. As a result, applying constraint optimization techniques to this problem has been infeasible. However, characteristic functions that appear in practice often can be represented concisely by a set of rules, rather than treating the function as a black box. Then we can solve the CSG problem more efficiently by directly applying constraint optimization techniques to this compact representation. We present new formalizations of the CSG problem by utilizing recently developed compact representation schemes for characteristic functions. We first characterize the complexity of CSG under these representation schemes. In this context, the complexity is driven more by the number of rules than by the number of agents. As an initial step toward developing efficient constraint optimization algorithms for solving the CSG problem, we also develop mixed integer programming formulations and show that an off-the-shelf optimization package can perform reasonably well.     

Strain-Dependent Dynamic Properties of Remolded Sand-Clay Mixtures

A series of undrained cyclic torsional simple shear tests using hollow cylindrical torsional shear apparatus was carried out to investigate the dynamic shear moduli and damping properties of clayey specimens with various sand contents and plasticity indices. The clayey soils used were collected from various sites along the coast of west Japan. Among these clayey soils, a clay sample with intermediate plasticity and another with high plasticity were mixed with silica sand at different proportions in order to examine the dynamic properties of sand-clay mixtures. In addition, experiments were carried out on undisturbed and remolded natural clay specimens with various plasticities. The effects of plasticity, loading frequency and confining pressure on the strain dependent normalized shear modulus and damping ratio were examined. Based on the results, empirical correlations for predicting the normalized shear modulus and damping ratio of remolded sand-clay mixtures at various shear strain levels were proposed.     

Internal Friction in Metaphosphate Glasses

The internal friction of metaphosphate glasses was measured as a function of temperature by a free torsional vibration method. In the high-temperature region metaphosphate glasses (MO/P₂O₅=l)for which M=Ca, Sr, or Ba exhibit high-temperature peaks in plots of internal friction vs temperature, whereas for M =Mg or Zn this peak is missing.