Development of fluidized bed gasifier with triple-beds and dual circulation

A new type of circulating fluidized bed gasifier was proposed. The main features of this proposed gasifier are the adoption of a triple-beds structure (comprising pyrolyzer, gasifier, and combustor), the separation of a circulation path for tar-absorbing material and that for the fuel and silica sand. Independent circulation systems are employed for the fuel system and for the tar-absorbing particles, and the pyrolyzer and gasifier each have a two-stage fluidized bed: the lower stage is for the fuel system and the upper stage is for the tar-absorbing particle system. The two circulation systems each have an independent combustor. In the pyrolyzer, the tar formed together with the gas produced during the pyrolysis of the fuel in the lower stage is absorbed by tar-absorbing particles in the upper stage. By adopting this two-stage fluidized bed approach, mixing of the tar-absorbing particles, which is rather expensive, with the ash contained in the fuel can be avoided. Accordingly, accumulation of ash in the circulation path for tar-absorbing material can be avoided, and the quantity of the discharge of absorption particles can be reduced. Therefore, the quantity used can be greatly reduced. The quantity of costly tar-absorbing particles used can be further minimized by optimizing the quantity of particles with respect to the quantity of tar generated by the fuel.As the first stage towards development of the proposed new type gasifier, the fundamental experiments that simulated a two-stage pyrolyzer and gasifier were carried out. As a result, the amount of H₂ formed by pyrolysis resulted in a marked increase by using porous alumina as the tar-absorbing particles than the conventional conditions of using only silica sand. The amount of H₂ formed was more increased because the coke was not only cracked but also reformed by steam gasification.     

Graded-index plastic optical fiber prepared by the coextrusion process

A graded-index plastic optical fiber (GI POF) has been proposed as the transmission medium to realize high-speed information transmission. We have succeeded in fabricating a GI POF by the dopant diffusion coextrusion process, a method that allows continuous fabrication of GI POF. Although it has been indicated that the refractive index distribution of GI POF fabricated by this process is formed by Fick diffusion with the diffusion coefficient dependent on dopant concentration, the method to control it remains unknown. The purposes of this study are to establish the technology of stable fabricating of GI POF by the coextrusion process and to analyze the bandwidth.     

Fabrication and Training of 3D Conductive Polymer Networks for Neuromorphic Wetware

The human brain possesses an exceptional information processing capability owing to the 3D and dense network architecture of numerous neurons and synapses. Brain-inspired neuromorphic hardware can also benefit from 3D architectures, such as high integration of circuits and acquisition of highly complex dynamical systems. In this study, for future 3D neuromorphic engineering, 3D conductive polymer networks consisting of poly(3,4-ethylenedioxy-thiophene) doped with poly(styrene sulfonate) anions (PEDOT:PSS) are successfully and stably fabricated between multiple electrodes from scratch in precursor solution by electropolymerization. The networks efficiently emulate the 3D local connections between neighboring neurons observed in the cortex. This novel technology, which allows 3D conductive wiring only between desired electrodes, is unprecedented and has potential as an underlying technology for 3D integration. Furthermore, the experimental results also conclusively prove that conductance modification can be performed by manipulating the physical and chemical properties of 3D branch-wired conductive polymer wires, thus demonstrating for the first time the feasibility of neuromorphic wetware with enhanced biological plausibility in the subsequent post-Moore era.     

Multi-agent consensus with stopping rules under bounded measurement noise

A multi-agent consensus protocol is investigated over noisy undirected connected graphs. It is supposed that each agent can know her neighbors' states with bounded noise. A theoretical stopping rule having a probabilistic guarantee is established for the consensus protocol, which explicitly relates the number of iterations with the closeness of the agreement. The stopping rule is derived by utilizing Bernstein inequality that deals with a given noise bound explicitly. The sample complexity with respect to the number of agents is also investigated, where it is shown that the number of iterations required by the proposed stopping rule based on the bound of noise itself is generally smaller than that of the conventional stopping rules that utilize bound of noise variance. The results are demonstrated through numerical examples.