The internal structural changes around the crack-tip and the pertinent crack growth behavior in an amorphous metal are studied by a large scale molecular dynamics (MD) simulation. The Finnis-Sinclair potential for α-...
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The internal structural changes around the crack-tip and the pertinent crack growth behavior in an amorphous metal are studied by a large scale molecular dynamics (MD) simulation. The Finnis-Sinclair potential for α-iron is used as an interatomic potential. The model amorphous metal was created by melting-rapid quenching simulation. The crack opens in similar fashion and it has smooth surfaces during the amorphous state. As it deformed, nano-scaled crystalline phase grows around the crack-tip. The distribution of deformation zones and deformation mechanism are significantly altered. The grains are not deformed while they are relatively small. The emission of dislocations from the crack-tip is observed, after the crystal phase covered the crack-tip surfaces. The grain size appeared small in the vicinity of the crack-tip, and becomes gradually large as it separates form the crack-tip.
We have developed a method of catalyst preparation for carbon nanotube (CNT) growth that uses solid-state diffusion to precipitate Co particles in a Cu matrix and control the size and size distribution of catalyst par...
We have developed a method of catalyst preparation for carbon nanotube (CNT) growth that uses solid-state diffusion to precipitate Co particles in a Cu matrix and control the size and size distribution of catalyst particles. Copper is an excellent electrical and thermal conductor, and has a small or negligible solubility for Co. Cu–Co alloys of approximately 5 atm% Co were formed in bulk by splat quenching the liquid alloy and on Si substrates by e-beam evaporation of the alloy, sputtering of the alloy, and sputter deposition of thin films of pure Cu and Co. The Co easily precipitates from dilute solutions of Cu–Co with heat treatment. These alloys and films were used to generate uniform distributions of Co precipitates, and CNTs were successfully grown by plasma enhanced chemical vapor deposition (PE-CVD) and thermal CVD on the materials. These alloys can be patterned by photolithography and sputtering in order to grow CNTs in defined locations. Therefore, the technique is amenable to very large scale silicon integration for field emission applications. The results of this work and data from field emission studies are presented herein.
Experimental evidences suggest involvement of the hippocampus in temporal sequence learning. Taking physiological differences between the hippocampal CA3 and CA1 regions into account, we propose a mechanism of tempora...
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Experimental evidences suggest involvement of the hippocampus in temporal sequence learning. Taking physiological differences between the hippocampal CA3 and CA1 regions into account, we propose a mechanism of temporal sequence encoding. Input signals that mimicked the activity of the rat entorhinal cortex during animal's spatial behavior were applied to a model hippocampal CA3-CA1 network. Following an organization of spatiotemporal patterns of spontaneous activity in the CA3 region, Schaffer collateral synaptic conductances were modified eventually forming a distinct spatial pattern. As a result, a CA1 pyramidal cell assembly was tuned to a specific sequence of input signals.
To help programmers debug visual programs, we propose an animated execution method with supporting functions to be used with the animated execution. The animated execution animates state transitions as the program is ...
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To help programmers debug visual programs, we propose an animated execution method with supporting functions to be used with the animated execution. The animated execution animates state transitions as the program is executed. To make it easy for the programmer to interpret the animation, it is displayed in a manner similar to the visual program. The functions are used to narrow the possible locations of bugs and to test fixed components quickly. We have implemented animated execution and the functions on 3D-PP, our three-dimensional visual programming system.
Anonymity can protect a user's privacy, however it is hard to manage. It is hard to disclose anonymously. In addition, it is also hard to make people trust anonymous information. In this paper, we provide a key ex...
ISBN:
(纸本)1581139551
Anonymity can protect a user's privacy, however it is hard to manage. It is hard to disclose anonymously. In addition, it is also hard to make people trust anonymous information. In this paper, we provide a key exchange scheme for not only anonymous, but also traceable disclosure. To be more precise, one who provides information can anonymously guarantee communication with particular person. Furthermore, his anonymity can be retained even if he discloses communication contents. These features can not realized by using signature scheme, or any other existing methods. Our method enable those features, and it can be useful when a group is dealing with confidential information. Copyright 2004 ACM.
A network model of the entorhinal cortex layer II that consisted of stellate cells and an interneuron was constructed. The stellate cell reproduced subthreshold oscillations in the theta range as observed in physiolog...
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A network model of the entorhinal cortex layer II that consisted of stellate cells and an interneuron was constructed. The stellate cell reproduced subthreshold oscillations in the theta range as observed in physiological experiments. The subthreshold oscillations were recurrently synchronized through an inhibitory interneuron, and theta rhythm was generated. Anatomical evidences suggest that the layers II and V of the entorhinal cortex and the hippocampus may form a loop circuit with a delay time of about 25 ms for signals going around. With the loop circuit introduced to the present model, the stellate cells that represent spatial information fired successively at intervals of 25 ms, in depolarized phases of the theta cycles. The present entorhinal cortex model with the loop circuits reproduced the phase precession, which has been observed experimentally as a characteristic of place cells.
In this paper, we study how to collect n balls moving with constant velocities in the Euclidean plane by k robots moving on straight track-lines through the origin. Since all the balls might not be caught by robots, d...
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In this paper, we study how to collect n balls moving with constant velocities in the Euclidean plane by k robots moving on straight track-lines through the origin. Since all the balls might not be caught by robots, differently from Moving-Target TSP, we consider the following 3 problems in various situations: (i) deciding if k robots can collect all n balls, (ii) maximizing the number of the balls collected by k robots, and (iii) minimizing the number of the robots to collect all n balls. The situations considered here contain the cases in which track-lines are given (or not), and track-lines are identical (or not). For all problems and situations, we provide polynomial time algorithms or proofs of intractability, which clarify the tractability-intractability frontier in the ball collecting problems in the Euclidean plane.
It is possible to enjoy the quality of service related informations of a single node or a link between two nodes, which is understandable for the technical people only. Yet, there is no zone-based quality of service i...
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An increasing biped robot development may be viewed in terms of realization of autonomous works in real world, where robot motion with lifting and/or carrying of heavy objects must be designed. Such motion control of ...
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An increasing biped robot development may be viewed in terms of realization of autonomous works in real world, where robot motion with lifting and/or carrying of heavy objects must be designed. Such motion control of biped robot working by himself is an important issues, in which many configurations and motions appear depending on position of robot and object. Isaka et al. analyzed the lifting motion of skilled lifter and mentioned that the configuration of lifting is important to realize the efficient lifting with small burden to the lower back. In their analysis the motion was limited for weight lift, and the object's position was fixed. So, it is required to analyze various human lifting motions in many situations for new biped robot control. Our study aims at realization of biped robot that can walk and lifting heavy objects. In this paper, dynamic characteristics of human lifting movement are analyzed through lifting of barbell in various situations. Furthermore, based on the lifting analysis, the comparison of motion control between lifting and jumping is discussed.
We propose a method of semantically nonmonotonic reasoning in prioritized knowledge bases based on incomplete information systems and granular reasoning. Our nonmonotonic reasoning is characterized as "reasoning ...
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We propose a method of semantically nonmonotonic reasoning in prioritized knowledge bases based on incomplete information systems and granular reasoning. Our nonmonotonic reasoning is characterized as "reasoning with disregard of difference of detail." We provide granularized models and priority of each rule, and formulate the method of semantically non-monotonic reasoning based on the idea of ignored sets, rejected sets and possible tuples of atomic sentences that we propose.
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