An entropy model for shear deformation of granular materials

A statistical mechanical analogy for characterization of granular materials is discussed by using such notions as the state of the material, the density of states, entropy, canonical distribution and the partition function. The transition law of states during shear deformations of the material is microscopically investigated in the case of two-dimensional model granular materials. The assumption of entropy growth is shown to characterize the dilatancy of the material. A rough proof is given by assuming the measure preserving property of the transition and showing its ergodicity.     

Biomagnetic approaches to studying the brain

Biomagnetic approaches to understanding the functional organization of the human brain include (1) transcranial magnetic stimulation (TMS), (2) magnetoencephalography (MEG) by superconducting quantum interference devices (SQUIDs), and (3) the imaging of electrical currents and impedance distributions of the head based on new principles of magnetic resonance imaging (MRI) techniques. These techniques are noninvasive and very useful for studying higher brain functions of humans such as memory and cognition. This article discusses these techniques, including the histories, principles, advantages, and disadvantages of each method, by using examples from studies recently conducted primarily in the author's laboratory     

Essential Factors for Shock Compaction of Diamond Composites

Shock compaction experiments for some diamond composites were carried out, and the best consolidated compacts of diamond/SiC and diamond/TiC had relative densities of 95% and 96%, and microhardnesses of 51 ± 2.9 and 48.6 ± 4.8 GPa, respectively. For obtaining better compacts on the shock compaction of mixtures, the ratio of the constituent particle sizes and the properties of the constituent materials are considered, and then the starting conditions of the mixtures must be decided. Here, a simple model concerned with the influence of both the ratio of the constituent particle sizes and the thermal properties of the constituent materials on the shock compaction of mixtures is also presented.     

Modeling of Consumer Choice Behavior as Sequential Decision Process

Behaviormetrika - This study proposes a model of consumer choice behavior as sequential decision process. It is hypothesized that consumers form desirable product model and undesirable one through...     

Characterization of crystalline silicon grown by plasma-enhanced CVD for thin-film solar cells

High growth-rate Si epitaxy by plasma-enhanced chemical vapor deposition (PECVD) has been investigated for a thin-film solar cell application. A high growth rate of 50 μm/h was obtained at 1050°C with plasma which is 50% larger than that by the conventional CVD without plasma. The electrical properties are almost the same for epitaxial layers with and without plasma. For undoped n-type layers, the Hall mobility and carrier density were about 600 cm²/V s and low 10¹⁵ cm⁻³, respectively. The electron diffusion length in doped p-type layers was about 20 μm. These electrical properties for the layer with plasma, in spite of higher growth rate, are comparable or better than those without plasma.     

Operation of a two-stage fermentation process producing hydrogen and methane from organic waste

A pilot-scale experimental plant for the production of hydrogen and methane by a two-stage fermentation process was constructed and operated using a mixture of pulverized garbage and shredded paper wastes. Thermophilic hydrogen fermentation was established at 60 degrees C in the first bioreactor by inoculating with seed microflora. Following the hydrogenogenic process, methanogenesis in the second bioreactor was conducted at 55 degrees C using an internal recirculation packed-bed reactor (IRPR). After conducting steady-state operations under a few selected conditions, the overall hydraulic retention time was optimized at 8 d (hydrogenogenesis, 1.2 d; methanogenesis, 6.8 d), producing 5.4 m3/m3/d of hydrogen and 6.1 m3/m3/d of methane with chemical oxygen demand and volatile suspended solid removal efficiencies of 79.3% and 87.8%, respectively. Maximum hydrogen production yield was calculated to be 2.4 mol/mol hexose and 56 L/kg COD loaded. The methanogenic performance of the IRPR was stable, although the organic loading rate and the composition of the effluent from the hydrogenogenic process fluctuated substantially. A clone library analysis of the microflora in the hydrogenogenic reactor indicated that hydrogen-producing Thermoanaerobacterium-related organisms in the inoculum were active in the hydrogen fermentation of garbage and paper wastes, although no aseptic operations were applied. We speculate that the operation at high temperature and the inoculation of thermophiles enabled the selective growth of the introduced microorganisms and gave hydrogen fermentation efficiencies comparable to laboratory experiments. This is the first report on fermentative production of hydrogen and methane from organic waste at an actual level.