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Modeling the Human Memory in Nerve Fields
Osamu FUJITA,Yukinori KAKAZU 대한전자공학회 1992 대한전자공학회 학술대회 Vol.1992 No.10
This paper describes the modeling of human memory using a nerve field model which is proposed for modeling the mechanism of brain mathmatically. In our model, two phases of memory, retention and recollection, are focused on. The former consists of two stages, short-term memory (STM) and long-term memory (LTM). The proposed model consists of three parts, the STM Layer, LTM Layer and the Intermediate Layer between them. Each of these is constructed by a nerve field. In the STM Layer, memorized information is retained dynamically in the form of the reverberating states of units within the layer, while in the LTM Layer, it is stored statically in the form of structures of the weight on the links between units. the Intermediate Layer is introduced to translate this dynamic representation in the STM Layer to the LTM Layer, and also to extract the static information from the STM Layer. In addition to this, we consider the recollection of information stored in the LTM. Finally, the behavior of this model is demonstrated by computer simulation.
A review of fine structures of nanoporous materials as evidenced by microscopic methods.
Liu, Zheng,Fujita, Nobuhisa,Miyasaka, Keiichi,Han, Lu,Stevens, Sam M,Suga, Mitsuo,Asahina, Shunsuke,Slater, Ben,Xiao, Changhong,Sakamoto, Yasuhiro,Anderson, Michael W,Ryoo, Ryong,Terasaki, Osamu Oxford University Press 2013 Microscopy Vol.62 No.1
<P>This paper reviews diverse capabilities offered by modern electron microscopy techniques in studying fine structures of nanoporous crystals such as zeolites, silica mesoporous crystals, metal organic frameworks and yolk-shell materials. For the case of silica mesoporous crystals, new approaches that have been developed recently to determine the three-dimensionally periodic average structure, e.g., through self-consistent analysis of electron microscope images or through consideration of accidental extinctions, are presented. Various structural deviations in nanoporous materials from their average structures including intergrowth, surface termination, incommensurate modulation, quasicrystal and defects are demonstrated. Ibidem observations of the scanning electron microscope and atomic force microscope give information about the zeolite-crystal-growth mechanism, and an energy for unstitching a building-unit from a crystal surface is directly observed by an anatomic force microscope. It is argued how these observations lead to a deeper understanding of the materials.</P>
Dodecagonal tiling in mesoporous silica
Xiao, Changhong,Fujita, Nobuhisa,Miyasaka, Keiichi,Sakamoto, Yasuhiro,Terasaki, Osamu Nature Publishing Group, a division of Macmillan P 2012 Nature Vol.487 No.7407
Recent advances in the fabrication of quasicrystals in soft matter systems have increased the length scales for quasicrystals into the mesoscale range (20 to 500 책ngstr철ms). Thus far, dendritic liquid crystals, ABC-star polymers, colloids and inorganic nanoparticles have been reported to yield quasicrystals. These quasicrystals offer larger length scales than intermetallic quasicrystals (a few 책ngstr철ms), thus potentially leading to optical applications through the realization of a complete photonic bandgap induced via multiple scattering of light waves in virtually all directions. However, the materials remain far from structurally ideal, in contrast to their intermetallic counterparts, and fine control over the structure through a self-organization process has yet to be attained. Here we use the well-established self-assembly of surfactant micelles to produce a new class of mesoporous silicas, which exhibit 12-fold (dodecagonal) symmetry in both electron diffraction and morphology. Each particle reveals, in the 12-fold cross-section, an analogue of dodecagonal quasicrystals in the centre surrounded by 12 fans of crystalline domains in the peripheral part. The quasicrystallinity has been verified by selected-area electron diffraction and quantitative phason strain analyses on transmission electron microscope images obtained from the central region. We argue that the structure forms through a non-equilibrium growth process, wherein the competition between different micellar configurations has a central role in tuning the structure. A simple theoretical model successfully reproduces the observed features and thus establishes a link between the formation process and the resulting structure.
최재혁,김준홍,최상규,전병호,Osamu Fujita,정석호 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.3
A numerical study on soot deposition in ethylene diffusion flames has been conducted to elucidate the effect of thermophoresis on soot particles under a microgravity environment. Time-dependent reactive-flow Navier-Stokes equations coupled with the modeling of soot formation have been solved. The model was validated by comparing the simulation results with the previous experimental data for a laminar diffusion flame of ethylene (C2H4) with enriched oxygen (35% O2 + 65% N2) along a solid wall. In particular, the effect of surrounding air velocity as a major calculation parameter has been investigated. Especially, the soot deposition length defined as the transverse travel distance to the wall in the streamwise direction is introduced as a parameter to evaluate the soot deposition tendency on the wall. The calculation result exhibits that there existed an optimal air velocity for the early deposition of soot on the surface, which was in good agreement with the previous experimental results. The reason has been attributed to the balance between the effects of the thermophoretic force and convective motion.
관내 예혼함 화염에서 외부 CO₂ 레이저 조사에 의한 화염면 진동의 동적거동
박준성(June Sung Park),Fujita Osamu,Nakamura Yuji,Ito Hiroyuki 한국연소학회 2009 KOSCOSYMPOSIUM논문집 Vol.- No.39
Experiments in premixed C₂H₄/CO₂-O₂ flames (Le < 1) in a tube have been conducted, the mixture was ignited at the top, open end of and propagating downwardly toward the closed end. to investigate the exact motion of flame tip fluctuations at the initial moment of irradiating CO₂ laser, the completely flat flame front is selected as a default flame, which is corresponding to the primary acoustic instability as reported by Searby.[1] During the laser exposure to the unburned mixture, the flame fronts had extremely unstable behaviors, resulting in a strong turbulent flame eventually through the secondary acoustic instability. To elucidate the effect of flame curvatures, the flame velocity and curvature prior to the secondary acoustic instability were analyzed by using captured high speed camera images. the results showed that a sudden acceleration at advancing waves was observed. And then, there was the time lag between the flame velocity and curvature, indicating the increase in the flame velocity even with decreasing flame curvature. these behaviors are closely relevant not only to the diffusive-thermal effects but also to the acoustic waves. the plausible mechanism was proposed in this paper based on the acoustic influence.