85 research outputs found
Suppression of surface segregation and heavy arsenic doping into silicon during selective epitaxial chemical vapor deposition under atmospheric pressure
No full textTetsuya Ikuta, Shigeru Fujita, Hayato Iwamoto, Shingo Kadomura, Takayoshi Shimura, Heiji Watanabe and Kiyoshi Yasutake, "Suppression of surface segregation and heavy arsenic doping into silicon during selective epitaxial chemical vapor deposition under atmospheric pressure", Appl. Phys. Lett. 91, 092115 (2007) https://doi.org/10.1063/1.2778539.The authors investigated the effects of the growth rate and temperature on the surface segregation during in situ As-doped selective epitaxial growth under atmospheric pressure. It was confirmed that high growth rate and high temperature suppress surface segregation. A film with a high As concentration (7.5× 10^{19} at. cm^3) and a smooth surface was obtained by optimizing these conditions
The effect of sanctions on the evolution of cooperation in linear division of labor
No full textThe evolution of cooperation is an unsolved research topic and has been investigated from the viewpoint of not only biology and other natural sciences but also social sciences. Much extant research has focused on the evolution of cooperation among peers. While, different players belonging to different organizations play different social roles, and players playing different social roles cooperate together to achieve their goals. We focus on the evolution of cooperation in linear division of labor that is defined as follows: a player in the i-th role interacts with a player in the i + 1-th role, and a player in the n-th role achieves their goal (1 <= i < n) if there are n roles in the division of labor. We take the industrial waste treatment process as an example for illustration. We consider three organizational roles and B-i is the i-th role. The player of B; can choose two strategies: legal treatment or illegal dumping, which can be interpreted as cooperation or defection (i = 1-3). With legally required treatment, the player of B-j pays a cost to ask the player of Bj+1 to treat the waste (j = 1, 2). Then, the cooperator of Bj+1 pays a cost to treat the waste properly. With illegal dumping, the player of Bi dumps the waste and does not pay any cost (i= 1-3). However, the waste dumped by the defector has negative environmental consequences, which all players in all roles suffer from. This situation is equivalent to a social dilemma encountered in common-pool resource management contexts. The administrative organ in Japan introduces two sanction systems to address the illegal dumping problem: the actor responsibility system and the producer responsibility system. In the actor responsibility system, if players in any role who choose defection are monitored and discovered, they are penalized via a fine. However, it is difficult to monitor and detect the violators, and this system does not work well. While, in the producer responsibility system, the player in B-1 is fined if the player cannot hand the manifest to the local administrative organ because the players of B-i (i=1-3) who choose defection do not hand the manifest to the player of B-1. We analyze this situation using the replicator equation. We reveal that (1) the three-role model has more empirical credibility than the two-role model including B-1 and B-3, and (2) the producer responsibility system promotes the evolution of cooperation more than the system without sanctioning. (3) the actor responsibility system does not promote the evolution of cooperation if monitoring and detecting defectors is unsuccessful. (C) 2017 Elsevier Ltd. All rights reserved
Improvement of a regularity condition for long-range scattering for NLS with critical homogeneous nonlinearity (Spectral and Scattering Theory and Related Topics)
No full textIn this note, we survey the results in the author with Masaki and Uriya [14, 17] for the final state problem for nonlinear Schrödinger equations with critical homogeneous nonlinearity which is not necessarily a polynomial. It is also mentioned that a regularity condition for the final data can be improved by estimates for the kind of asymptotics of the solution developed by Kawamoto and the author [12]
Effect of the determination method of the material parameters on the accuracy of the hole expansion simulation for cold rolled steel sheet
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Application of non-destructive integrated CT-XRD method to investigate alteration of cementitious materials subjected to high temperature and pure water
No full textIn order to analyze the alteration mechanism after the exposure to various maximum temperatures and immersion in pure water, non-destructive integrated CT-XRD method (the CT-XRD) was applied. Firstly, the verification of the CT-XRD was carried out to compare with conventional powder X-ray diffraction. It revealed that the CT-XRD could evaluate the crystals properly with a given limitation for low energy band. Besides, the CT-XRD indicated the advantage that can detect the presence of crystals which cannot be detected after grinding in preparing the powder sample for the conventional powder XRD. Then, the carbonated cement paste that was heated at 200, 400, 600, and 800 degrees C followed by immersion in pure water was evaluated by the CT-XRD. The results suggest that sample heated at 400 degrees C showed the resistance of leaching at most. In addition, rehydration of clinker minerals generated due to heating at 800 degrees C could be identified although the hydration product was easily dissolved into water
Evaluation of suitable conditions for natural regeneration of Picea jezoensis on fallen logs
No full textThe abundance of Picea jezoensis, a major conifer tree species in Hokkaido, northern Japan, is currently decreasing due to the lack of suitable conditions for recruitment and intensive harvests. To contribute to the development of sustainable forest management in Hokkaido, suitable substrates for natural regeneration of P. jezoensis were evaluated during a 4-year experimental study using seed additions in a natural coniferous forest. The environmental conditions (moss height, log hardness, extent of the humus layer, and light conditions) of fallen logs were measured. Moss height was categorized into three groups: 0 mm, Bark; 0 - 20 mm, Mthin; and ≥ 20 mm, Mthick. The germination rates of P. jezoensis were highest on Mthin, intermediate on Bark, and lowest on Mthick. Survival rates were low on Mthick, did not differ between Bark and Mthin, and increased with enhanced light. Growth increased with light, but the root allocation of seedlings was not affected by any environmental conditions. From these results, we determined that fallen logs with no or thin moss cover under bright conditions were most suitable for P. jezoensis regeneration. We discussed the generality of our results in relation to a co-occurring tree species in Hokkaido and the results of other regions
Macrosegregation simulation model based on Lattice-Boltzmann method with high computational efficiency
No full textA macrosegregation simulation model is developed by coupling solute and energy conservation equations with Lattice-Boltzmann Method (LBM), newly developing technique of computational fluid dynamics. Effect of the solidification shrinkage is taken into account in the present LBM as well as effects of the Darcy's flow and thermos-solutal convection. The present LBM-coupled model is based on modified lattice Bhadnager-Gross-Krook method, the numerical stability of which is better than that of the standard LBM. Accordingly, the present LBM-coupled model can be applied to simulations of macrosegregation behaviors in metallic alloy systems that cannot be handled by the previous LBM-coupled model. The validity of the model was demonstrated by comparing the results for steady-state flows with those of analytical solutions and a conventional model based on the Navier-Stokes equation. In addition, the computational speed of the present model is compared with the one of conventional model in cases of lateral directional solidification of Sn-Bi alloy and continuous casting of a steel slab. It is shown that the present LBM-coupled model enables remarkably faster computation than the conventional model especially in the latter case. (C) 2018 Elsevier Ltd. All rights reserved
On operator-valued monotone independence
No full textWe investigate operator-valued monotone independence, a noncommutative version of independence for conditional expectation. First we introduce operator-valued monotone cumulants to clarify the whole theory and show the moment-cumulant formula. As an application, one can obtain an easy proof of the central limit theorem for the operator-valued case. Moreover, we prove a generalization of Muraki’s formula for the sum of independent random variables and a relation between generating functions of moments and cumulants
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