Cooperative behavior control of robot group using stress antibody allotment reward

Lately, development in robotics for utilizing in both industry and home is in much progress. In this research, a group of robots is made to handle relatively complicated tasks. Cooperative action among robots is one of the research areas in robotics that is progressing remarkably well. Reinforcement learning is known as a common approach in robotics for deploying acquisition of action under dynamic environment. However, until recently, reinforcement learning is only applied to one agent problem. In multi-agent environment where plural robots exist, it was difficult to differentiate between learning of achievement of task and learning of performing cooperative action. This paper introduces a method of implementing reinforcement learning to induce cooperation among a group of robots where its task is to transport luggage of various weights to a destination. The general Q-learning method is used as a learning algorithm. Also, the switching of learning mode is proposed for reduction of learning time and learning area. Finally, grid world simulation is carried out to evaluate the proposed methods.     

Interaction of newly defined stress intensity factors for angular corners in a row of diamond-shaped inclusions

This paper deals with a row of equally spaced equal diamond-shaped inclusions with angular corners under various loading conditions. The problem is formulated as a system of singular integral equations with Cauchy-type singularities, where the unknown functions are the densities of body forces distributed in infinite plates having the same elastic constants of the matrix and inclusions. In order to analyze the problems accurately, the unknown functions of the body force densities are expressed as a linear combination of two types of fundamental density functions and power series, where the fundamental density functions are chosen to represent the symmetric stress singularity of $1/r^{1 - \lambda _1 } $ and the skew-symmetric stress singularity of $1/r^{1 - \lambda _2 } $ . Then, newly defined stress intensity factors for angular corners are systematically calculated for various shapes, spacings, elastic constants and numbers of the diamond-shaped inclusions in a plate subjected to uniaxial tension, biaxial tension and in-plane shear. For all types of diamond-shaped inclusions, the stress intensity factor is shown to be linearly related to the reciprocal of the number of diamond-shaped inclusions.     

Investigation of efficient protection from an influenza pandemic using CARMS

The new influenza A virus H1N1-pdm is spreading all over the world, including Japan. Since most people are not immunized against this new influenza virus, it is spreading very quickly. Currently, we have two options for the prevention of this disease, i.e., vaccination and antiviral drugs. Of these, vaccination is the best means of mass protection. However, the current system of vaccine production places limits on the number of units and the preparation time. To understand “the most efficient mass protection,” we simulated the spread of influenza by using the cellular abstract rewriting system on multisets (CARMS).     

Acquiring non-parametric scattering phase function from a single image

Computational Visual Media - Acquiring accurate scattering properties is important for rendering translucent materials. In particular, the phase function, which determines the distribution of...     

Temperature distribution in a workpiece during cylindrical plunge grinding

In cylindrical plunge grinding, a large amount of heat flows into the workpiece continuously, accumulates and remains even after the process, which causes dimensional error. Therefore it is necessary to investigate the temperature distribution in the workpiece during grinding and analyze the influence of grinding heat on the dimension. Such an investigation has not been done enough, because the technology to measure the temperature distribution in the rotating workpiece has not matured. Considering such background, an in-process measuring system has been developed, which makes it possible to detect the temperature distribution in a wide range from the outer surface to the inside of the rotating workpiece. The system consists of small temperature sensors which are embedded into the workpiece, a micro computer attached on the workpiece which acquires the data from the sensors and transmits to a personal computer by a wireless communication device. Furthermore the contact type thermocouple which enables to measure the rotating surface temperature is added to the system. Measurement experiments revealed that the grinding heat conducts from the workpiece surface toward the center, accumulates, and remains in the workpiece even after the process. Heat conduction simulation was also performed. Good agreement was achieved between the simulated temperatures and experimental measurements.     

Reducing the size distortion of the KPSS test

This article proposes a new stationarity test based on the KPSS test with less size distortion. We extend the boundary rule proposed by Sul et al. (2005) to the autoregressive spectral density estimator and parametrically estimate the long‐run variance. We also derive the finite sample bias of the numerator of the test statistic up to the 1/T order and propose a correction to the bias term in the numerator. Finite sample simulations show that the correction term effectively reduces the bias in the numerator and that the finite sample size of our test is close to the nominal one as long as the long‐run parameter in the model satisfies the boundary condition.     

放射性廃棄物量を低減するための低放射化材料の開発(英文)

原子炉などの施設が寿命を迎えると莫大な量の放射性廃棄物が発生する.であるのであらかじめ設計段階から廃棄物が出ないようなプランが必要である.その方法は(1)セメント·骨材·鉄筋などのマテリアルデータベース、(2)データベースに基いた低放射化セメント·鉄筋などの製造·採用、(3)原子炉遮蔽壁などへの施工·解体の最適化から生まれる.低放射化骨材·セメント·混和材量により低放射化コンクリートは可能になる.それらを適切に組み合わせることにより、従来型の原子炉壁使用コンクリートの1/10,1/20,1/30,...,1/1000,1/3000,1/10 000の低放射化が計れる.1/10,の低放射化とは仮想安山岩を骨材とした普通コンクリートをベースに計算される.そしてこれらは改良型BWRあるいはPWR原子炉用コンクリートに用いた場合、解体時のクリアランスレベル以下に廃棄物をすることが期待される.低放射化コンクリートを製造するために肝心なことは、放射化しやすい核種を含まないことであり、それは低放射化セメントや石灰石骨材を用いたり、高炉スラグや石炭灰を用いないことである.放射化しやすい各種とはEuとCoである.     

Interaction Nets With Nested Pattern Matching

Reduction rules in Interaction Nets are constrained to pattern match exactly one argument at a time. Consequently, a programmer has to introduce auxiliary rules to perform more sophisticated matches. We propose an extension of Interaction Nets which facilitates nested pattern matching on interaction rules. We then define a practical compilation scheme from extended rules to pure interaction rules. We achieve a system that provides convenient ways to express Interaction Net programs without defining auxiliary rules.     

Solar cell of 6.3% efficiency employing high deposition rate (8 nm/s) microcrystalline silicon photovoltaic layer

Microcrystalline silicon (μc-Si) films deposited at high growth rates up to 8.1 nm/s prepared by very-high-frequency-plasma-enhanced chemical vapor deposition (VHF-PECVD) at 18–24 Torr have been investigated. The relation between the deposition rates and input power revealed the depletion of silane. Under high-pressure deposition (HPD) conditions, the structural properties were improved. Furthermore, applying μc-Si to n–i–p solar cells, short-circuit current density (J_SC) was increased in accordance with the improvement of microstructure of i-layer. As a result, a conversion efficiency of 6.30% has been achieved employing the i-layer deposited at 8.1 nm/s under the HPD conditions.     

Strain-induced crystallization of peroxide-crosslinked natural rubber

Effect of network-chain density (ν) on the strain-induced crystallization of peroxide-crosslinked natural rubber was studied by fast time-resolved synchrotron wide-angle X-ray diffraction. It was observed that the elongation ratio at the onset of strain-induced crystallization (α_c) became smaller with the increase of ν. The difference of the entropy between the undeformed and deformed states at each α_c was nearly equal in spite of the variation of ν. The calculated melting temperature at α_c of the samples was also almost the same regardless of their ν. These observations mean that the strain-induced crystallization occurred when the deformation brought about a definite entropic state for peroxide-crosslinked natural rubber. They agreed with the prediction by Flory and were consistent with the classical theory of rubber elasticity.